String

• Method

java.lang

Class String

• java.lang.Object
• • java.lang.String

• All Implemented Interfaces:
  Serializable,CharSequence,Comparable<String>

  ---

  
  

  public final classStringextendsObjectimplementsSerializable,Comparable<String>,CharSequence

  TheStringclassrepresents(代表) character strings. All stringliterals(字面值) in Java programs,such as(比如)"abc", are implemented(实现) asinstances(实例) of this class.

  Strings areconstant(常量); their values cannot be changed after they are created. String bufferssupport(支持)mutable strings(可变字符串). Because String objects are immutable(不可变的) they can beshared(共享). For example:

  String str = "abc";

  is equivalent to(相当于):

  char data[] = {'a', 'b', 'c'}; String str = new String(data);

  Here are some more examples of how strings can be used:

  System.out.println("abc"); String cde = "cde"; System.out.println("abc" + cde); String c = "abc".substring(2,3); String d = cde.substring(1, 2);

  The classStringincludes methods forexamining(检查)individual characters(单个字符串) of thesequence(序列), forcomparing(比较) strings, forsearchin(搜索) strings, forextracting(提取)substrings(子字符串), and for creating a copy of a string with all characters translated to uppercase or to lowercase.Casemapping(大小写映射) is based on the Unicode Standard version specified by theCharacterclass.

  The Java language provides special support for the stringconcatenation（串联）operator(操作符) ( + ), and for conversion of other objects to strings. String concatenation is implementedthrough(通过) theStringBuilder(orStringBuffer) class and itsappendmethod. String conversions are implemented through the methodtoString, defined byObjectandinherited(继承) by all classes in Java. For additional(额外的) information on string concatenation and conversion, see Gosling, Joy, and Steele,The Java Language Specification.

  Unless otherwise noted（除非另外说明）,passing(传入) anullargument to a constructor(构造) or method in this class will cause aNullPointerExceptionto be thrown.

  AStringrepresents a string in the UTF-16 format in whichsupplementary charactersare represented bysurrogate pairs(see the sectionUnicode Character Representationsin theCharacterclass for more information). Index valuesrefer(指) tocharcode units, so asupplementary character(补充的字符) uses twopositions(位置) in aString.

  TheStringclass provides methods fordealing with(处理) Unicode code points (i.e., characters),in addition(除...之外) to those for dealing with Unicode code units (i.e.,charvalues).

  Since:
  JDK1.0
  See Also:
  Object.toString(),StringBuffer,StringBuilder,Charset,Serialized Form

• • Field Summary

    Fields Modifier and Type Field and Description

    staticComparator<String>	CASE_INSENSITIVE_ORDER A Comparator that ordersStringobjects as bycompareToIgnoreCase.

  • Constructor Summary

    Constructors Constructor and Description
    String()

    Initializes a newly createdStringobject so that it represents an empty character sequence.
    String(byte[] bytes)

    Constructs a newStringby decoding the specified array of bytes using the platform's default charset.
    String(byte[] bytes,Charsetcharset)

    Constructs a newStringby decoding the specified array of bytes using the specifiedcharset.
    String(byte[] ascii, int hibyte)

    Deprecated.

    This method does not properly convert bytes into characters. As of JDK 1.1, the preferred way to do this is via theStringconstructors that take aCharset, charset name, or that use the platform's default charset.
    String(byte[] bytes, int offset, int length)

    Constructs a newStringby decoding the specified subarray of bytes using the platform's default charset.
    String(byte[] bytes, int offset, int length,Charsetcharset)

    Constructs a newStringby decoding the specified subarray of bytes using the specifiedcharset.
    String(byte[] ascii, int hibyte, int offset, int count)

    Deprecated.

    This method does not properly convert bytes into characters. As of JDK 1.1, the preferred way to do this is via theStringconstructors that take aCharset, charset name, or that use the platform's default charset.
    String(byte[] bytes, int offset, int length,StringcharsetName)

    Constructs a newStringby decoding the specified subarray of bytes using the specified charset.
    String(byte[] bytes,StringcharsetName)

    Constructs a newStringby decoding the specified array of bytes using the specifiedcharset.
    String(char[] value)

    Allocates a newStringso that it represents the sequence of characters currently contained in the character array argument.
    String(char[] value, int offset, int count)

    Allocates a newStringthat contains characters from a subarray of the character array argument.
    String(int[] codePoints, int offset, int count)

    Allocates a newStringthat contains characters from a subarray of theUnicode code pointarray argument.
    String(Stringoriginal)

    Initializes a newly createdStringobject so that it represents the same sequence of characters as the argument; in other words, the newly created string is a copy of the argument string.
    String(StringBufferbuffer)

    Allocates a new string that contains the sequence of characters currently contained in the string buffer argument.
    String(StringBuilderbuilder)

    Allocates a new string that contains the sequence of characters currently contained in the string builder argument.

  • Method Summary

    Methods Modifier and Type Method and Description

    char	charAt(int index) Returns thecharvalue at the specified index.
    int	codePointAt(int index) Returns the character (Unicode code point) at the specified index.
    int	codePointBefore(int index) Returns the character (Unicode code point) before the specified index.
    int	codePointCount(int beginIndex, int endIndex) Returns the number of Unicode code points in the specified text range of thisString.
    int	compareTo(StringanotherString) Compares two strings lexicographically.
    int	compareToIgnoreCase(Stringstr) Compares two strings lexicographically, ignoring case differences.
    String	concat(Stringstr) Concatenates the specified string to the end of this string.
    boolean	contains(CharSequences) Returns true if and only if this string contains the specified sequence of char values.
    boolean	contentEquals(CharSequencecs) Compares this string to the specifiedCharSequence.
    boolean	contentEquals(StringBuffersb) Compares this string to the specifiedStringBuffer.
    staticString	copyValueOf(char[] data) Returns a String that represents the character sequence in the array specified.
    staticString	copyValueOf(char[] data, int offset, int count) Returns a String that represents the character sequence in the array specified.
    boolean	endsWith(Stringsuffix) Tests if this string ends with the specified suffix.
    boolean	equals(ObjectanObject) Compares this string to the specified object.
    boolean	equalsIgnoreCase(StringanotherString) Compares thisStringto anotherString, ignoring case considerations.
    staticString	format(Localel,Stringformat,Object... args) Returns a formatted string using the specified locale, format string, and arguments.
    staticString	format(Stringformat,Object... args) Returns a formatted string using the specified format string and arguments.
    byte[]	getBytes() Encodes thisStringinto a sequence of bytes using the platform's default charset, storing the result into a new byte array.
    byte[]	getBytes(Charsetcharset) Encodes thisStringinto a sequence of bytes using the givencharset, storing the result into a new byte array.
    void	getBytes(int srcBegin, int srcEnd, byte[] dst, int dstBegin) Deprecated. This method does not properly convert characters into bytes. As of JDK 1.1, the preferred way to do this is via thegetBytes()method, which uses the platform's default charset.
    byte[]	getBytes(StringcharsetName) Encodes thisStringinto a sequence of bytes using the named charset, storing the result into a new byte array.
    void	getChars(int srcBegin, int srcEnd, char[] dst, int dstBegin) Copies characters from this string into the destination character array.
    int	hashCode() Returns a hash code for this string.
    int	indexOf(int ch) Returns the index within this string of the first occurrence of the specified character.
    int	indexOf(int ch, int fromIndex) Returns the index within this string of the first occurrence of the specified character, starting the search at the specified index.
    int	indexOf(Stringstr) Returns the index within this string of the first occurrence of the specified substring.
    int	indexOf(Stringstr, int fromIndex) Returns the index within this string of the first occurrence of the specified substring, starting at the specified index.
    String	intern() Returns a canonical representation for the string object.
    boolean	isEmpty() Returnstrueif, and only if,length()is0.
    int	lastIndexOf(int ch) Returns the index within this string of the last occurrence of the specified character.
    int	lastIndexOf(int ch, int fromIndex) Returns the index within this string of the last occurrence of the specified character, searching backward starting at the specified index.
    int	lastIndexOf(Stringstr) Returns the index within this string of the last occurrence of the specified substring.
    int	lastIndexOf(Stringstr, int fromIndex) Returns the index within this string of the last occurrence of the specified substring, searching backward starting at the specified index.
    int	length() Returns the length of this string.
    boolean	matches(Stringregex) Tells whether or not this string matches the givenregular expression.
    int	offsetByCodePoints(int index, int codePointOffset) Returns the index within thisStringthat is offset from the givenindexbycodePointOffsetcode points.
    boolean	regionMatches(boolean ignoreCase, int toffset,Stringother, int ooffset, int len) Tests if two string regions are equal.
    boolean	regionMatches(int toffset,Stringother, int ooffset, int len) Tests if two string regions are equal.
    String	replace(char oldChar, char newChar) Returns a new string resulting from replacing all occurrences ofoldCharin this string withnewChar.
    String	replace(CharSequencetarget,CharSequencereplacement) Replaces each substring of this string that matches the literal target sequence with the specified literal replacement sequence.
    String	replaceAll(Stringregex,Stringreplacement) Replaces each substring of this string that matches the givenregular expressionwith the given replacement.
    String	replaceFirst(Stringregex,Stringreplacement) Replaces the first substring of this string that matches the givenregular expressionwith the given replacement.
    String[]	split(Stringregex) Splits this string around matches of the givenregular expression.
    String[]	split(Stringregex, int limit) Splits this string around matches of the givenregular expression.
    boolean	startsWith(Stringprefix) Tests if this string starts with the specified prefix.
    boolean	startsWith(Stringprefix, int toffset) Tests if the substring of this string beginning at the specified index starts with the specified prefix.
    CharSequence	subSequence(int beginIndex, int endIndex) Returns a new character sequence that is a subsequence of this sequence.
    String	substring(int beginIndex) Returns a new string that is a substring of this string.
    String	substring(int beginIndex, int endIndex) Returns a new string that is a substring of this string.
    char[]	toCharArray() Converts this string to a new character array.
    String	toLowerCase() Converts all of the characters in thisStringto lower case using the rules of the default locale.
    String	toLowerCase(Localelocale) Converts all of the characters in thisStringto lower case using the rules of the givenLocale.
    String	toString() This object (which is already a string!) is itself returned.
    String	toUpperCase() Converts all of the characters in thisStringto upper case using the rules of the default locale.
    String	toUpperCase(Localelocale) Converts all of the characters in thisStringto upper case using the rules of the givenLocale.
    String	trim() Returns a copy of the string, with leading and trailing whitespace omitted.
    staticString	valueOf(boolean b) Returns the string representation of thebooleanargument.
    staticString	valueOf(char c) Returns the string representation of thecharargument.
    staticString	valueOf(char[] data) Returns the string representation of thechararray argument.
    staticString	valueOf(char[] data, int offset, int count) Returns the string representation of a specific subarray of thechararray argument.
    staticString	valueOf(double d) Returns the string representation of thedoubleargument.
    staticString	valueOf(float f) Returns the string representation of thefloatargument.
    staticString	valueOf(int i) Returns the string representation of theintargument.
    staticString	valueOf(long l) Returns the string representation of thelongargument.
    staticString	valueOf(Objectobj) Returns the string representation of theObjectargument.

    • Methods inherited from class java.lang.Object

      clone,finalize,getClass,notify,notifyAll,wait,wait,wait

• • Field Detail

    • CASE_INSENSITIVE_ORDER

      public static finalComparator<String> CASE_INSENSITIVE_ORDER

      A Comparator that ordersStringobjects as bycompareToIgnoreCase. This comparator is serializable.

      Note that this Comparator doesnottake locale into account, and will result in an unsatisfactory ordering for certain locales. The java.text package providesCollatorsto allow locale-sensitive ordering.

      Since:
      1.2
      See Also:
      Collator.compare(String, String)

  • Constructor Detail

    • String

      public String()

      Initializes a newly createdStringobject so that it represents an empty character sequence. Note that use of this constructor is unnecessary since Strings are immutable.

    • String

      public String(Stringoriginal)

      Initializes a newly createdStringobject so that it represents the same sequence of characters as the argument; in other words, the newly created string is a copy of the argument string. Unless an explicit copy oforiginalis needed, use of this constructor is unnecessary since Strings are immutable.
      Parameters:
      original- AString

    • String

      public String(char[] value)

      Allocates a newStringso that it represents the sequence of characters currently contained in the character array argument. The contents of the character array are copied; subsequent modification of the character array does not affect the newly created string.
      Parameters:
      value- The initial value of the string

    • String

      public String(char[] value, int offset, int count)

      Allocates a newStringthat contains characters from a subarray of the character array argument. Theoffsetargument is the index of the first character of the subarray and thecountargument specifies the length of the subarray. The contents of the subarray are copied; subsequent modification of the character array does not affect the newly created string.
      Parameters:
      value- Array that is the source of characters
      offset- The initial offset
      count- The length
      Throws:
      IndexOutOfBoundsException- If theoffsetandcountarguments index characters outside the bounds of thevaluearray

    • String

      public String(int[] codePoints, int offset, int count)

      Allocates a newStringthat contains characters from a subarray of theUnicode code pointarray argument. Theoffsetargument is the index of the first code point of the subarray and thecountargument specifies the length of the subarray. The contents of the subarray are converted tochars; subsequent modification of theintarray does not affect the newly created string.
      Parameters:
      codePoints- Array that is the source of Unicode code points
      offset- The initial offset
      count- The length
      Throws:
      IllegalArgumentException- If any invalid Unicode code point is found incodePoints
      IndexOutOfBoundsException- If theoffsetandcountarguments index characters outside the bounds of thecodePointsarray
      Since:
      1.5

    • String

      @Deprecatedpublic String(byte[] ascii, int hibyte, int offset, int count)

      Deprecated.This method does not properly convert bytes into characters. As of JDK 1.1, the preferred way to do this is via theStringconstructors that take aCharset, charset name, or that use the platform's default charset.
      Allocates a newStringconstructed from a subarray of an array of 8-bit integer values.

      Theoffsetargument is the index of the first byte of the subarray, and thecountargument specifies the length of the subarray.

      Eachbytein the subarray is converted to acharas specified in the method above.

      Parameters:
      ascii- The bytes to be converted to characters
      hibyte- The top 8 bits of each 16-bit Unicode code unit
      offset- The initial offset
      count- The length
      Throws:
      IndexOutOfBoundsException- If theoffsetorcountargument is invalid
      See Also:
      String(byte[], int),String(byte[], int, int, java.lang.String),String(byte[], int, int, java.nio.charset.Charset),String(byte[], int, int),String(byte[], java.lang.String),String(byte[], java.nio.charset.Charset),String(byte[])

    • String

      @Deprecatedpublic String(byte[] ascii, int hibyte)

      Deprecated.This method does not properly convert bytes into characters. As of JDK 1.1, the preferred way to do this is via theStringconstructors that take aCharset, charset name, or that use the platform's default charset.
      Allocates a newStringcontaining characters constructed from an array of 8-bit integer values. Each charactercin the resulting string is constructed from the corresponding componentbin the byte array such that:

      c== (char)(((hibyte & 0xff) << 8) | (b& 0xff))

      Parameters:
      ascii- The bytes to be converted to characters
      hibyte- The top 8 bits of each 16-bit Unicode code unit
      See Also:
      String(byte[], int, int, java.lang.String),String(byte[], int, int, java.nio.charset.Charset),String(byte[], int, int),String(byte[], java.lang.String),String(byte[], java.nio.charset.Charset),String(byte[])

    • String

      public String(byte[] bytes, int offset, int length,StringcharsetName) throwsUnsupportedEncodingException

      Constructs a newStringby decoding the specified subarray of bytes using the specified charset. The length of the newStringis a function of the charset, and hence may not be equal to the length of the subarray.

      The behavior of this constructor when the given bytes are not valid in the given charset is unspecified. TheCharsetDecoderclass should be used when more control over the decoding process is required.

      Parameters:
      bytes- The bytes to be decoded into characters
      offset- The index of the first byte to decode
      length- The number of bytes to decode
      charsetName- The name of a supportedcharset
      Throws:
      UnsupportedEncodingException- If the named charset is not supported
      IndexOutOfBoundsException- If theoffsetandlengtharguments index characters outside the bounds of thebytesarray
      Since:
      JDK1.1

    • String

      public String(byte[] bytes, int offset, int length,Charsetcharset)

      Constructs a newStringby decoding the specified subarray of bytes using the specifiedcharset. The length of the newStringis a function of the charset, and hence may not be equal to the length of the subarray.

      This method always replaces malformed-input and unmappable-character sequences with this charset's default replacement string. TheCharsetDecoderclass should be used when more control over the decoding process is required.

      Parameters:
      bytes- The bytes to be decoded into characters
      offset- The index of the first byte to decode
      length- The number of bytes to decode
      charset- Thecharsetto be used to decode thebytes
      Throws:
      IndexOutOfBoundsException- If theoffsetandlengtharguments index characters outside the bounds of thebytesarray
      Since:
      1.6

    • String

      public String(byte[] bytes,StringcharsetName) throwsUnsupportedEncodingException

      Constructs a newStringby decoding the specified array of bytes using the specifiedcharset. The length of the newStringis a function of the charset, and hence may not be equal to the length of the byte array.

      The behavior of this constructor when the given bytes are not valid in the given charset is unspecified. TheCharsetDecoderclass should be used when more control over the decoding process is required.

      Parameters:
      bytes- The bytes to be decoded into characters
      charsetName- The name of a supportedcharset
      Throws:
      UnsupportedEncodingException- If the named charset is not supported
      Since:
      JDK1.1

    • String

      public String(byte[] bytes,Charsetcharset)

      Constructs a newStringby decoding the specified array of bytes using the specifiedcharset. The length of the newStringis a function of the charset, and hence may not be equal to the length of the byte array.

      This method always replaces malformed-input and unmappable-character sequences with this charset's default replacement string. TheCharsetDecoderclass should be used when more control over the decoding process is required.

      Parameters:
      bytes- The bytes to be decoded into characters
      charset- Thecharsetto be used to decode thebytes
      Since:
      1.6

    • String

      public String(byte[] bytes, int offset, int length)

      Constructs a newStringby decoding the specified subarray of bytes using the platform's default charset. The length of the newStringis a function of the charset, and hence may not be equal to the length of the subarray.

      The behavior of this constructor when the given bytes are not valid in the default charset is unspecified. TheCharsetDecoderclass should be used when more control over the decoding process is required.

      Parameters:
      bytes- The bytes to be decoded into characters
      offset- The index of the first byte to decode
      length- The number of bytes to decode
      Throws:
      IndexOutOfBoundsException- If theoffsetand thelengtharguments index characters outside the bounds of thebytesarray
      Since:
      JDK1.1

    • String

      public String(byte[] bytes)

      Constructs a newStringby decoding the specified array of bytes using the platform's default charset. The length of the newStringis a function of the charset, and hence may not be equal to the length of the byte array.

      The behavior of this constructor when the given bytes are not valid in the default charset is unspecified. TheCharsetDecoderclass should be used when more control over the decoding process is required.

      Parameters:
      bytes- The bytes to be decoded into characters
      Since:
      JDK1.1

    • String

      public String(StringBufferbuffer)

      Allocates a new string that contains the sequence of characters currently contained in the string buffer argument. The contents of the string buffer are copied; subsequent modification of the string buffer does not affect the newly created string.
      Parameters:
      buffer- AStringBuffer

    • String

      public String(StringBuilderbuilder)

      Allocates a new string that contains the sequence of characters currently contained in the string builder argument. The contents of the string builder are copied; subsequent modification of the string builder does not affect the newly created string.

      This constructor is provided to ease migration toStringBuilder. Obtaining a string from a string builder via thetoStringmethod is likely to run faster and is generally preferred.

      Parameters:
      builder- AStringBuilder
      Since:
      1.5

  • Method Detail

    • length

      public int length()

      Returns the length of this string. The length is equal to the number ofUnicode code unitsin the string.
      Specified by:
      lengthin interfaceCharSequence
      Returns:
      the length of the sequence of characters represented by this object.

    • isEmpty

      public boolean isEmpty()

      Returnstrueif, and only if,length()is0.
      Returns:
      trueiflength()is0, otherwisefalse
      Since:
      1.6

    • charAt

      public char charAt(int index)

      Returns thecharvalue at the specified index. An index ranges from0tolength() - 1. The firstcharvalue of the sequence is at index0, the next at index1, and so on, as for array indexing.

      If thecharvalue specified by the index is asurrogate, the surrogate value is returned.

      Specified by:
      charAtin interfaceCharSequence
      Parameters:
      index- the index of thecharvalue.
      Returns:
      thecharvalue at the specified index of this string. The firstcharvalue is at index0.
      Throws:
      IndexOutOfBoundsException- if theindexargument is negative or not less than the length of this string.

    • codePointAt

      public int codePointAt(int index)

      Returns the character (Unicode code point) at the specified index. The index refers tocharvalues (Unicode code units) and ranges from0tolength()- 1.

      If thecharvalue specified at the given index is in the high-surrogate range, the following index is less than the length of thisString, and thecharvalue at the following index is in the low-surrogate range, then the supplementary code point corresponding to this surrogate pair is returned. Otherwise, thecharvalue at the given index is returned.

      Parameters:
      index- the index to thecharvalues
      Returns:
      the code point value of the character at theindex
      Throws:
      IndexOutOfBoundsException- if theindexargument is negative or not less than the length of this string.
      Since:
      1.5

    • codePointBefore

      public int codePointBefore(int index)

      Returns the character (Unicode code point) before the specified index. The index refers tocharvalues (Unicode code units) and ranges from1tolength.

      If thecharvalue at(index - 1)is in the low-surrogate range,(index - 2)is not negative, and thecharvalue at(index - 2)is in the high-surrogate range, then the supplementary code point value of the surrogate pair is returned. If thecharvalue atindex - 1is an unpaired low-surrogate or a high-surrogate, the surrogate value is returned.

      Parameters:
      index- the index following the code point that should be returned
      Returns:
      the Unicode code point value before the given index.
      Throws:
      IndexOutOfBoundsException- if theindexargument is less than 1 or greater than the length of this string.
      Since:
      1.5

    • codePointCount

      public int codePointCount(int beginIndex, int endIndex)

      Returns the number of Unicode code points in the specified text range of thisString. The text range begins at the specifiedbeginIndexand extends to thecharat indexendIndex - 1. Thus the length (inchars) of the text range isendIndex-beginIndex. Unpaired surrogates within the text range count as one code point each.
      Parameters:
      beginIndex- the index to the firstcharof the text range.
      endIndex- the index after the lastcharof the text range.
      Returns:
      the number of Unicode code points in the specified text range
      Throws:
      IndexOutOfBoundsException- if thebeginIndexis negative, orendIndexis larger than the length of thisString, orbeginIndexis larger thanendIndex.
      Since:
      1.5

    • offsetByCodePoints

      public int offsetByCodePoints(int index, int codePointOffset)

      Returns the index within thisStringthat is offset from the givenindexbycodePointOffsetcode points. Unpaired surrogates within the text range given byindexandcodePointOffsetcount as one code point each.
      Parameters:
      index- the index to be offset
      codePointOffset- the offset in code points
      Returns:
      the index within thisString
      Throws:
      IndexOutOfBoundsException- ifindexis negative or larger then the length of thisString, or ifcodePointOffsetis positive and the substring starting withindexhas fewer thancodePointOffsetcode points, or ifcodePointOffsetis negative and the substring beforeindexhas fewer than the absolute value ofcodePointOffsetcode points.
      Since:
      1.5

    • getChars

      public void getChars(int srcBegin, int srcEnd, char[] dst, int dstBegin)

      Copies characters from this string into the destination character array.

      The first character to be copied is at indexsrcBegin; the last character to be copied is at indexsrcEnd-1(thus the total number of characters to be copied issrcEnd-srcBegin). The characters are copied into the subarray ofdststarting at indexdstBeginand ending at index:

      dstbegin + (srcEnd-srcBegin) - 1

      Parameters:
      srcBegin- index of the first character in the string to copy.
      srcEnd- index after the last character in the string to copy.
      dst- the destination array.
      dstBegin- the start offset in the destination array.
      Throws:
      IndexOutOfBoundsException- If any of the following is true:

      • srcBeginis negative.
      • srcBeginis greater thansrcEnd
      • srcEndis greater than the length of this string
      • dstBeginis negative
      • dstBegin+(srcEnd-srcBegin)is larger thandst.length

    • getBytes

      @Deprecatedpublic void getBytes(int srcBegin, int srcEnd, byte[] dst, int dstBegin)

      Deprecated.This method does not properly convert characters into bytes. As of JDK 1.1, the preferred way to do this is via thegetBytes()method, which uses the platform's default charset.
      Copies characters from this string into the destination byte array. Each byte receives the 8 low-order bits of the corresponding character. The eight high-order bits of each character are not copied and do not participate in the transfer in any way.

      The first character to be copied is at indexsrcBegin; the last character to be copied is at indexsrcEnd-1. The total number of characters to be copied issrcEnd-srcBegin. The characters, converted to bytes, are copied into the subarray ofdststarting at indexdstBeginand ending at index:

      dstbegin + (srcEnd-srcBegin) - 1

      Parameters:
      srcBegin- Index of the first character in the string to copy
      srcEnd- Index after the last character in the string to copy
      dst- The destination array
      dstBegin- The start offset in the destination array
      Throws:
      IndexOutOfBoundsException- If any of the following is true:

      • srcBeginis negative
      • srcBeginis greater thansrcEnd
      • srcEndis greater than the length of this String
      • dstBeginis negative
      • dstBegin+(srcEnd-srcBegin)is larger thandst.length

    • getBytes

      public byte[] getBytes(StringcharsetName) throwsUnsupportedEncodingException

      Encodes thisStringinto a sequence of bytes using the named charset, storing the result into a new byte array.

      The behavior of this method when this string cannot be encoded in the given charset is unspecified. TheCharsetEncoderclass should be used when more control over the encoding process is required.

      Parameters:
      charsetName- The name of a supportedcharset
      Returns:
      The resultant byte array
      Throws:
      UnsupportedEncodingException- If the named charset is not supported
      Since:
      JDK1.1

    • getBytes

      public byte[] getBytes(Charsetcharset)

      Encodes thisStringinto a sequence of bytes using the givencharset, storing the result into a new byte array.

      This method always replaces malformed-input and unmappable-character sequences with this charset's default replacement byte array. TheCharsetEncoderclass should be used when more control over the encoding process is required.

      Parameters:
      charset- TheCharsetto be used to encode theString
      Returns:
      The resultant byte array
      Since:
      1.6

    • getBytes

      public byte[] getBytes()

      Encodes thisStringinto a sequence of bytes using the platform's default charset, storing the result into a new byte array.

      The behavior of this method when this string cannot be encoded in the default charset is unspecified. TheCharsetEncoderclass should be used when more control over the encoding process is required.

      Returns:
      The resultant byte array
      Since:
      JDK1.1

    • equals

      public boolean equals(ObjectanObject)

      Compares this string to the specified object. The result istrueif and only if the argument is notnulland is aStringobject that represents the same sequence of characters as this object.
      Overrides:
      equalsin classObject
      Parameters:
      anObject- The object to compare thisStringagainst
      Returns:
      trueif the given object represents aStringequivalent to this string,falseotherwise
      See Also:
      compareTo(String),equalsIgnoreCase(String)

    • contentEquals

      public boolean contentEquals(StringBuffersb)

      Compares this string to the specifiedStringBuffer. The result istrueif and only if thisStringrepresents the same sequence of characters as the specifiedStringBuffer.
      Parameters:
      sb- TheStringBufferto compare thisStringagainst
      Returns:
      trueif thisStringrepresents the same sequence of characters as the specifiedStringBuffer,falseotherwise
      Since:
      1.4

    • contentEquals

      public boolean contentEquals(CharSequencecs)

      Compares this string to the specifiedCharSequence. The result istrueif and only if thisStringrepresents the same sequence of char values as the specified sequence.
      Parameters:
      cs- The sequence to compare thisStringagainst
      Returns:
      trueif thisStringrepresents the same sequence of char values as the specified sequence,falseotherwise
      Since:
      1.5

    • equalsIgnoreCase

      public boolean equalsIgnoreCase(StringanotherString)

      Compares thisStringto anotherString, ignoring case considerations. Two strings are considered equal ignoring case if they are of the same length and corresponding characters in the two strings are equal ignoring case.

      Two charactersc1andc2are considered the same ignoring case if at least one of the following is true:

      • The two characters are the same (as compared by the==operator)
      • Applying the methodCharacter.toUpperCase(char)to each character produces the same result
      • Applying the methodCharacter.toLowerCase(char)to each character produces the same result
      Parameters:
      anotherString- TheStringto compare thisStringagainst
      Returns:
      trueif the argument is notnulland it represents an equivalentStringignoring case;falseotherwise
      See Also:
      equals(Object)

    • compareTo

      public int compareTo(StringanotherString)

      Compares two strings lexicographically. The comparison is based on the Unicode value of each character in the strings. The character sequence represented by thisStringobject is compared lexicographically to the character sequence represented by the argument string. The result is a negative integer if thisStringobject lexicographically precedes the argument string. The result is a positive integer if thisStringobject lexicographically follows the argument string. The result is zero if the strings are equal;compareToreturns0exactly when theequals(Object)method would returntrue.

      This is the definition of lexicographic ordering. If two strings are different, then either they have different characters at some index that is a valid index for both strings, or their lengths are different, or both. If they have different characters at one or more index positions, letkbe the smallest such index; then the string whose character at positionkhas the smaller value, as determined by using the < operator, lexicographically precedes the other string. In this case,compareToreturns the difference of the two character values at positionkin the two string -- that is, the value:

      this.charAt(k)-anotherString.charAt(k)

      If there is no index position at which they differ, then the shorter string lexicographically precedes the longer string. In this case,compareToreturns the difference of the lengths of the strings -- that is, the value:

      this.length()-anotherString.length()

      Specified by:
      compareToin interfaceComparable<String>
      Parameters:
      anotherString- theStringto be compared.
      Returns:
      the value0if the argument string is equal to this string; a value less than0if this string is lexicographically less than the string argument; and a value greater than0if this string is lexicographically greater than the string argument.

    • compareToIgnoreCase

      public int compareToIgnoreCase(Stringstr)

      Compares two strings lexicographically, ignoring case differences. This method returns an integer whose sign is that of callingcompareTowith normalized versions of the strings where case differences have been eliminated by callingCharacter.toLowerCase(Character.toUpperCase(character))on each character.

      Note that this method doesnottake locale into account, and will result in an unsatisfactory ordering for certain locales. The java.text package providescollatorsto allow locale-sensitive ordering.

      Parameters:
      str- theStringto be compared.
      Returns:
      a negative integer, zero, or a positive integer as the specified String is greater than, equal to, or less than this String, ignoring case considerations.
      Since:
      1.2
      See Also:
      Collator.compare(String, String)

    • regionMatches

      public boolean regionMatches(int toffset,Stringother, int ooffset, int len)

      Tests if two string regions are equal.

      A substring of thisStringobject is compared to a substring of the argument other. The result is true if these substrings represent identical character sequences. The substring of thisStringobject to be compared begins at indextoffsetand has lengthlen. The substring of other to be compared begins at indexooffsetand has lengthlen. The result isfalseif and only if at least one of the following is true:

      • toffsetis negative.
      • ooffsetis negative.
      • toffset+lenis greater than the length of thisStringobject.
      • ooffset+lenis greater than the length of the other argument.
      • There is some nonnegative integerkless thanlensuch that:this.charAt(toffset+k) != other.charAt(ooffset+k)
      Parameters:
      toffset- the starting offset of the subregion in this string.
      other- the string argument.
      ooffset- the starting offset of the subregion in the string argument.
      len- the number of characters to compare.
      Returns:
      trueif the specified subregion of this string exactly matches the specified subregion of the string argument;falseotherwise.

    • regionMatches

      public boolean regionMatches(boolean ignoreCase, int toffset,Stringother, int ooffset, int len)

      Tests if two string regions are equal.

      A substring of thisStringobject is compared to a substring of the argumentother. The result istrueif these substrings represent character sequences that are the same, ignoring case if and only ifignoreCaseis true. The substring of thisStringobject to be compared begins at indextoffsetand has lengthlen. The substring ofotherto be compared begins at indexooffsetand has lengthlen. The result isfalseif and only if at least one of the following is true:

      • toffsetis negative.
      • ooffsetis negative.
      • toffset+lenis greater than the length of thisStringobject.
      • ooffset+lenis greater than the length of the other argument.
      • ignoreCaseisfalseand there is some nonnegative integerkless thanlensuch that:

        this.charAt(toffset+k) != other.charAt(ooffset+k)

      • ignoreCaseistrueand there is some nonnegative integerkless thanlensuch that:

        Character.toLowerCase(this.charAt(toffset+k)) != Character.toLowerCase(other.charAt(ooffset+k))

        and:

        Character.toUpperCase(this.charAt(toffset+k)) != Character.toUpperCase(other.charAt(ooffset+k))

      Parameters:
      ignoreCase- iftrue, ignore case when comparing characters.
      toffset- the starting offset of the subregion in this string.
      other- the string argument.
      ooffset- the starting offset of the subregion in the string argument.
      len- the number of characters to compare.
      Returns:
      trueif the specified subregion of this string matches the specified subregion of the string argument;falseotherwise. Whether the matching is exact or case insensitive depends on theignoreCaseargument.

    • startsWith

      public boolean startsWith(Stringprefix, int toffset)

      Tests if the substring of this string beginning at the specified index starts with the specified prefix.
      Parameters:
      prefix- the prefix.
      toffset- where to begin looking in this string.
      Returns:
      trueif the character sequence represented by the argument is a prefix of the substring of this object starting at indextoffset;falseotherwise. The result isfalseiftoffsetis negative or greater than the length of thisStringobject; otherwise the result is the same as the result of the expression

      this.substring(toffset).startsWith(prefix)

    • startsWith

      public boolean startsWith(Stringprefix)

      Tests if this string starts with the specified prefix.
      Parameters:
      prefix- the prefix.
      Returns:
      trueif the character sequence represented by the argument is a prefix of the character sequence represented by this string;falseotherwise. Note also thattruewill be returned if the argument is an empty string or is equal to thisStringobject as determined by theequals(Object)method.
      Since:
      1. 0

    • endsWith

      public boolean endsWith(Stringsuffix)

      Tests if this string ends with the specified suffix.
      Parameters:
      suffix- the suffix.
      Returns:
      trueif the character sequence represented by the argument is a suffix of the character sequence represented by this object;falseotherwise. Note that the result will betrueif the argument is the empty string or is equal to thisStringobject as determined by theequals(Object)method.

    • hashCode

      public int hashCode()

      Returns a hash code for this string. The hash code for aStringobject is computed as

      s[0]*31^(n-1) + s[1]*31^(n-2) + ... + s[n-1]

      usingintarithmetic, wheres[i]is theith character of the string,nis the length of the string, and^indicates exponentiation. (The hash value of the empty string is zero.)
      Overrides:
      hashCodein classObject
      Returns:
      a hash code value for this object.
      See Also:
      Object.equals(java.lang.Object),System.identityHashCode(java.lang.Object)

    • indexOf

      public int indexOf(int ch)

      Returns the index within this string of the first occurrence of the specified character. If a character with valuechoccurs in the character sequence represented by thisStringobject, then the index (in Unicode code units) of the first such occurrence is returned. For values ofchin the range from 0 to 0xFFFF (inclusive), this is the smallest valueksuch that:

      this.charAt(k) == ch

      is true. For other values ofch, it is the smallest valueksuch that:

      this.codePointAt(k) == ch

      is true. In either case, if no such character occurs in this string, then-1is returned.
      Parameters:
      ch- a character (Unicode code point).
      Returns:
      the index of the first occurrence of the character in the character sequence represented by this object, or-1if the character does not occur.

    • indexOf

      public int indexOf(int ch, int fromIndex)

      Returns the index within this string of the first occurrence of the specified character, starting the search at the specified index.

      If a character with valuechoccurs in the character sequence represented by thisStringobject at an index no smaller thanfromIndex, then the index of the first such occurrence is returned. For values ofchin the range from 0 to 0xFFFF (inclusive), this is the smallest valueksuch that:

      (this.charAt(k) == ch) && (k>= fromIndex)

      is true. For other values ofch, it is the smallest valueksuch that:

      (this.codePointAt(k) == ch) && (k>= fromIndex)

      is true. In either case, if no such character occurs in this string at or after positionfromIndex, then-1is returned.

      There is no restriction on the value offromIndex. If it is negative, it has the same effect as if it were zero: this entire string may be searched. If it is greater than the length of this string, it has the same effect as if it were equal to the length of this string:-1is returned.

      All indices are specified incharvalues (Unicode code units).

      Parameters:
      ch- a character (Unicode code point).
      fromIndex- the index to start the search from.
      Returns:
      the index of the first occurrence of the character in the character sequence represented by this object that is greater than or equal tofromIndex, or-1if the character does not occur.

    • lastIndexOf

      public int lastIndexOf(int ch)

      Returns the index within this string of the last occurrence of the specified character. For values ofchin the range from 0 to 0xFFFF (inclusive), the index (in Unicode code units) returned is the largest valueksuch that:

      this.charAt(k) == ch

      is true. For other values ofch, it is the largest valueksuch that:

      this.codePointAt(k) == ch

      is true. In either case, if no such character occurs in this string, then-1is returned. TheStringis searched backwards starting at the last character.
      Parameters:
      ch- a character (Unicode code point).
      Returns:
      the index of the last occurrence of the character in the character sequence represented by this object, or-1if the character does not occur.

    • lastIndexOf

      public int lastIndexOf(int ch, int fromIndex)

      Returns the index within this string of the last occurrence of the specified character, searching backward starting at the specified index. For values ofchin the range from 0 to 0xFFFF (inclusive), the index returned is the largest valueksuch that:

      (this.charAt(k) == ch) && (k<= fromIndex)

      is true. For other values ofch, it is the largest valueksuch that:

      (this.codePointAt(k) == ch) && (k<= fromIndex)

      is true. In either case, if no such character occurs in this string at or before positionfromIndex, then-1is returned.

      All indices are specified incharvalues (Unicode code units).

      Parameters:
      ch- a character (Unicode code point).
      fromIndex- the index to start the search from. There is no restriction on the value offromIndex. If it is greater than or equal to the length of this string, it has the same effect as if it were equal to one less than the length of this string: this entire string may be searched. If it is negative, it has the same effect as if it were -1: -1 is returned.
      Returns:
      the index of the last occurrence of the character in the character sequence represented by this object that is less than or equal tofromIndex, or-1if the character does not occur before that point.

    • indexOf

      public int indexOf(Stringstr)

      Returns the index within this string of the first occurrence of the specified substring.

      The returned index is the smallest valuekfor which:

      this.startsWith(str,k)

      If no such value ofkexists, then-1is returned.
      Parameters:
      str- the substring to search for.
      Returns:
      the index of the first occurrence of the specified substring, or-1if there is no such occurrence.

    • indexOf

      public int indexOf(Stringstr, int fromIndex)

      Returns the index within this string of the first occurrence of the specified substring, starting at the specified index.

      The returned index is the smallest valuekfor which:

      k>= fromIndex && this.startsWith(str,k)

      If no such value ofkexists, then-1is returned.
      Parameters:
      str- the substring to search for.
      fromIndex- the index from which to start the search.
      Returns:
      the index of the first occurrence of the specified substring, starting at the specified index, or-1if there is no such occurrence.

    • lastIndexOf

      public int lastIndexOf(Stringstr)

      Returns the index within this string of the last occurrence of the specified substring. The last occurrence of the empty string "" is considered to occur at the index valuethis.length().

      The returned index is the largest valuekfor which:

      this.startsWith(str,k)

      If no such value ofkexists, then-1is returned.
      Parameters:
      str- the substring to search for.
      Returns:
      the index of the last occurrence of the specified substring, or-1if there is no such occurrence.

    • lastIndexOf

      public int lastIndexOf(Stringstr, int fromIndex)

      Returns the index within this string of the last occurrence of the specified substring, searching backward starting at the specified index.

      The returned index is the largest valuekfor which:

      k<= fromIndex && this.startsWith(str,k)

      If no such value ofkexists, then-1is returned.
      Parameters:
      str- the substring to search for.
      fromIndex- the index to start the search from.
      Returns:
      the index of the last occurrence of the specified substring, searching backward from the specified index, or-1if there is no such occurrence.

    • substring

      publicStringsubstring(int beginIndex)

      Returns a new string that is a substring of this string. The substring begins with the character at the specified index and extends to the end of this string.

      Examples:

      "unhappy".substring(2) returns "happy" "Harbison".substring(3) returns "bison" "emptiness".substring(9) returns "" (an empty string)

      Parameters:
      beginIndex- the beginning index, inclusive.
      Returns:
      the specified substring.
      Throws:
      IndexOutOfBoundsException- ifbeginIndexis negative or larger than the length of thisStringobject.

    • substring

      publicStringsubstring(int beginIndex, int endIndex)

      Returns a new string that is a substring of this string. The substring begins at the specifiedbeginIndexand extends to the character at indexendIndex - 1. Thus the length of the substring isendIndex-beginIndex.

      Examples:

      "hamburger".substring(4, 8) returns "urge" "smiles".substring(1, 5) returns "mile"

      Parameters:
      beginIndex- the beginning index, inclusive.
      endIndex- the ending index, exclusive.
      Returns:
      the specified substring.
      Throws:
      IndexOutOfBoundsException- if thebeginIndexis negative, orendIndexis larger than the length of thisStringobject, orbeginIndexis larger thanendIndex.

    • subSequence

      publicCharSequencesubSequence(int beginIndex, int endIndex)

      Returns a new character sequence that is a subsequence of this sequence.

      An invocation of this method of the form

      str.subSequence(begin, end)

      behaves in exactly the same way as the invocation

      str.substring(begin, end)

      This method is defined so that theStringclass can implement theCharSequenceinterface.
      Specified by:
      subSequencein interfaceCharSequence
      Parameters:
      beginIndex- the begin index, inclusive.
      endIndex- the end index, exclusive.
      Returns:
      the specified subsequence.
      Throws:
      IndexOutOfBoundsException- ifbeginIndexorendIndexare negative, ifendIndexis greater thanlength(), or ifbeginIndexis greater thanstartIndex
      Since:
      1.4

    • concat

      publicStringconcat(Stringstr)

      Concatenates the specified string to the end of this string.

      If the length of the argument string is0, then thisStringobject is returned. Otherwise, a newStringobject is created, representing a character sequence that is the concatenation of the character sequence represented by thisStringobject and the character sequence represented by the argument string.

      Examples:

      "cares".concat("s") returns "caress" "to".concat("get").concat("her") returns "together"

      Parameters:
      str- theStringthat is concatenated to the end of thisString.
      Returns:
      a string that represents the concatenation of this object's characters followed by the string argument's characters.

    • replace

      publicStringreplace(char oldChar, char newChar)

      Returns a new string resulting from replacing all occurrences ofoldCharin this string withnewChar.

      If the characteroldChardoes not occur in the character sequence represented by thisStringobject, then a reference to thisStringobject is returned. Otherwise, a newStringobject is created that represents a character sequence identical to the character sequence represented by thisStringobject, except that every occurrence ofoldCharis replaced by an occurrence ofnewChar.

      Examples:

      "mesquite in your cellar".replace('e', 'o') returns "mosquito in your collar" "the war of baronets".replace('r', 'y') returns "the way of bayonets" "sparring with a purple porpoise".replace('p', 't') returns "starring with a turtle tortoise" "JonL".replace('q', 'x') returns "JonL" (no change)

      Parameters:
      oldChar- the old character.
      newChar- the new character.
      Returns:
      a string derived from this string by replacing every occurrence ofoldCharwithnewChar.

    • matches

      public boolean matches(Stringregex)

      Tells whether or not this string matches the givenregular expression.

      An invocation of this method of the formstr.matches(regex)yields exactly the same result as the expression

      Pattern.matches(regex,str)

      Parameters:
      regex- the regular expression to which this string is to be matched
      Returns:
      trueif, and only if, this string matches the given regular expression
      Throws:
      PatternSyntaxException- if the regular expression's syntax is invalid
      Since:
      1.4
      See Also:
      Pattern

    • contains

      public boolean contains(CharSequences)

      Returns true if and only if this string contains the specified sequence of char values.
      Parameters:
      s- the sequence to search for
      Returns:
      true if this string containss, false otherwise
      Throws:
      NullPointerException- ifsisnull
      Since:
      1.5

    • replaceFirst

      publicStringreplaceFirst(Stringregex,Stringreplacement)

      Replaces the first substring of this string that matches the givenregular expressionwith the given replacement.

      An invocation of this method of the formstr.replaceFirst(regex,repl)yields exactly the same result as the expression

      Pattern.compile(regex).matcher(str).replaceFirst(repl)

      Note that backslashes (\) and dollar signs ($) in the replacement string may cause the results to be different than if it were being treated as a literal replacement string; seeMatcher.replaceFirst(java.lang.String). UseMatcher.quoteReplacement(java.lang.String)to suppress the special meaning of these characters, if desired.

      Parameters:
      regex- the regular expression to which this string is to be matched
      replacement- the string to be substituted for the first match
      Returns:
      The resultingString
      Throws:
      PatternSyntaxException- if the regular expression's syntax is invalid
      Since:
      1.4
      See Also:
      Pattern

    • replaceAll

      publicStringreplaceAll(Stringregex,Stringreplacement)

      Replaces each substring of this string that matches the givenregular expressionwith the given replacement.

      An invocation of this method of the formstr.replaceAll(regex,repl)yields exactly the same result as the expression

      Pattern.compile(regex).matcher(str).replaceAll(repl)

      Note that backslashes (\) and dollar signs ($) in the replacement string may cause the results to be different than if it were being treated as a literal replacement string; seeMatcher.replaceAll. UseMatcher.quoteReplacement(java.lang.String)to suppress the special meaning of these characters, if desired.

      Parameters:
      regex- the regular expression to which this string is to be matched
      replacement- the string to be substituted for each match
      Returns:
      The resultingString
      Throws:
      PatternSyntaxException- if the regular expression's syntax is invalid
      Since:
      1.4
      See Also:
      Pattern

    • replace

      publicStringreplace(CharSequencetarget,CharSequencereplacement)

      Replaces each substring of this string that matches the literal target sequence with the specified literal replacement sequence. The replacement proceeds from the beginning of the string to the end, for example, replacing "aa" with "b" in the string "aaa" will result in "ba" rather than "ab".
      Parameters:
      target- The sequence of char values to be replaced
      replacement- The replacement sequence of char values
      Returns:
      The resulting string
      Throws:
      NullPointerException- iftargetorreplacementisnull.
      Since:
      1.5

    • split

      publicString[] split(Stringregex, int limit)

      Splits this string around matches of the givenregular expression.

      The array returned by this method contains each substring of this string that is terminated by another substring that matches the given expression or is terminated by the end of the string. The substrings in the array are in the order in which they occur in this string. If the expression does not match any part of the input then the resulting array has just one element, namely this string.

      Thelimitparameter controls the number of times the pattern is applied and therefore affects the length of the resulting array. If the limitnis greater than zero then the pattern will be applied at mostn- 1 times, the array's length will be no greater thann, and the array's last entry will contain all input beyond the last matched delimiter. Ifnis non-positive then the pattern will be applied as many times as possible and the array can have any length. Ifnis zero then the pattern will be applied as many times as possible, the array can have any length, and trailing empty strings will be discarded.

      The string"boo:and:foo", for example, yields the following results with these parameters:

      Regex Limit Result

      :	2	{ "boo", "and:foo" }
      :	5	{ "boo", "and", "foo" }
      :	-2	{ "boo", "and", "foo" }
      o	5	{ "b", "", ":and:f", "", "" }
      o	-2	{ "b", "", ":and:f", "", "" }
      o	0	{ "b", "", ":and:f" }

      An invocation of this method of the formstr.split(regex,n)yields the same result as the expression

      Pattern.compile(regex).split(str,n)

      Parameters:
      regex- the delimiting regular expression
      limit- the result threshold, as described above
      Returns:
      the array of strings computed by splitting this string around matches of the given regular expression
      Throws:
      PatternSyntaxException- if the regular expression's syntax is invalid
      Since:
      1.4
      See Also:
      Pattern

    • split

      publicString[] split(Stringregex)

      Splits this string around matches of the givenregular expression.

      This method works as if by invoking the two-argumentsplitmethod with the given expression and a limit argument of zero. Trailing empty strings are therefore not included in the resulting array.

      The string"boo:and:foo", for example, yields the following results with these expressions:

      Regex Result

      :	{ "boo", "and", "foo" }
      o	{ "b", "", ":and:f" }

      Parameters:
      regex- the delimiting regular expression
      Returns:
      the array of strings computed by splitting this string around matches of the given regular expression
      Throws:
      PatternSyntaxException- if the regular expression's syntax is invalid
      Since:
      1.4
      See Also:
      Pattern

    • toLowerCase

      publicStringtoLowerCase(Localelocale)

      Converts all of the characters in thisStringto lower case using the rules of the givenLocale. Case mapping is based on the Unicode Standard version specified by theCharacterclass. Since case mappings are not always 1:1 char mappings, the resultingStringmay be a different length than the originalString.

      Examples of lowercase mappings are in the following table:

      Language Code of Locale Upper Case Lower Case Description

      tr (Turkish)	\u0130	\u0069	capital letter I with dot above -> small letter i
      tr (Turkish)	\u0049	\u0131	capital letter I -> small letter dotless i
      (all)	French Fries	french fries	lowercased all chars in String
      (all)			lowercased all chars in String

      Parameters:
      locale- use the case transformation rules for this locale
      Returns:
      theString, converted to lowercase.
      Since:
      1.1
      See Also:
      toLowerCase(),toUpperCase(),toUpperCase(Locale)

    • toLowerCase

      publicStringtoLowerCase()

      Converts all of the characters in thisStringto lower case using the rules of the default locale. This is equivalent to callingtoLowerCase(Locale.getDefault()).

      Note:This method is locale sensitive, and may produce unexpected results if used for strings that are intended to be interpreted locale independently. Examples are programming language identifiers, protocol keys, and HTML tags. For instance,"TITLE".toLowerCase()in a Turkish locale returns"t\u0131tle", where '\u0131' is the LATIN SMALL LETTER DOTLESS I character. To obtain correct results for locale insensitive strings, usetoLowerCase(Locale.ENGLISH).

      Returns:
      theString, converted to lowercase.
      See Also:
      toLowerCase(Locale)

    • toUpperCase

      publicStringtoUpperCase(Localelocale)

      Converts all of the characters in thisStringto upper case using the rules of the givenLocale. Case mapping is based on the Unicode Standard version specified by theCharacterclass. Since case mappings are not always 1:1 char mappings, the resultingStringmay be a different length than the originalString.

      Examples of locale-sensitive and 1:M case mappings are in the following table.

      Language Code of Locale Lower Case Upper Case Description

      tr (Turkish)	\u0069	\u0130	small letter i -> capital letter I with dot above
      tr (Turkish)	\u0131	\u0049	small letter dotless i -> capital letter I
      (all)	\u00df	\u0053 \u0053	small letter sharp s -> two letters: SS
      (all)	Fahrvergnügen	FAHRVERGNÜGEN

      Parameters:
      locale- use the case transformation rules for this locale
      Returns:
      theString, converted to uppercase.
      Since:
      1.1
      See Also:
      toUpperCase(),toLowerCase(),toLowerCase(Locale)

    • toUpperCase

      publicStringtoUpperCase()

      Converts all of the characters in thisStringto upper case using the rules of the default locale. This method is equivalent totoUpperCase(Locale.getDefault()).

      Note:This method is locale sensitive, and may produce unexpected results if used for strings that are intended to be interpreted locale independently. Examples are programming language identifiers, protocol keys, and HTML tags. For instance,"title".toUpperCase()in a Turkish locale returns"T\u0130TLE", where '\u0130' is the LATIN CAPITAL LETTER I WITH DOT ABOVE character. To obtain correct results for locale insensitive strings, usetoUpperCase(Locale.ENGLISH).

      Returns:
      theString, converted to uppercase.
      See Also:
      toUpperCase(Locale)

    • trim

      publicStringtrim()

      Returns a copy of the string, with leading and trailing whitespace omitted.

      If thisStringobject represents an empty character sequence, or the first and last characters of character sequence represented by thisStringobject both have codes greater than'\u0020'(the space character), then a reference to thisStringobject is returned.

      Otherwise, if there is no character with a code greater than'\u0020'in the string, then a newStringobject representing an empty string is created and returned.

      Otherwise, letkbe the index of the first character in the string whose code is greater than'\u0020', and letmbe the index of the last character in the string whose code is greater than'\u0020'. A newStringobject is created, representing the substring of this string that begins with the character at indexkand ends with the character at indexm-that is, the result ofthis.substring(k,m+1).

      This method may be used to trim whitespace (as defined above) from the beginning and end of a string.

      Returns:
      A copy of this string with leading and trailing white space removed, or this string if it has no leading or trailing white space.

    • toString

      publicStringtoString()

      This object (which is already a string!) is itself returned.
      Specified by:
      toStringin interfaceCharSequence
      Overrides:
      toStringin classObject
      Returns:
      the string itself.

    • toCharArray

      public char[] toCharArray()

      Converts this string to a new character array.
      Returns:
      a newly allocated character array whose length is the length of this string and whose contents are initialized to contain the character sequence represented by this string.

    • format

      public staticStringformat(Stringformat,Object... args)

      Returns a formatted string using the specified format string and arguments.

      The locale always used is the one returned byLocale.getDefault().

      Parameters:
      format- Aformat string
      args- Arguments referenced by the format specifiers in the format string. If there are more arguments than format specifiers, the extra arguments are ignored. The number of arguments is variable and may be zero. The maximum number of arguments is limited by the maximum dimension of a Java array as defined by theJava Virtual Machine Specification. The behaviour on anullargument depends on theconversion.
      Returns:
      A formatted string
      Throws:
      IllegalFormatException- If a format string contains an illegal syntax, a format specifier that is incompatible with the given arguments, insufficient arguments given the format string, or other illegal conditions. For specification of all possible formatting errors, see theDetailssection of the formatter class specification.
      NullPointerException- If theformatisnull
      Since:
      1.5
      See Also:
      Formatter

    • format

      public staticStringformat(Localel,Stringformat,Object... args)

      Returns a formatted string using the specified locale, format string, and arguments.
      Parameters:
      l- Thelocaleto apply during formatting. Iflisnullthen no localization is applied.
      format- Aformat string
      args- Arguments referenced by the format specifiers in the format string. If there are more arguments than format specifiers, the extra arguments are ignored. The number of arguments is variable and may be zero. The maximum number of arguments is limited by the maximum dimension of a Java array as defined by theJava Virtual Machine Specification. The behaviour on anullargument depends on theconversion.
      Returns:
      A formatted string
      Throws:
      IllegalFormatException- If a format string contains an illegal syntax, a format specifier that is incompatible with the given arguments, insufficient arguments given the format string, or other illegal conditions. For specification of all possible formatting errors, see theDetailssection of the formatter class specification
      NullPointerException- If theformatisnull
      Since:
      1.5
      See Also:
      Formatter

    • valueOf

      public staticStringvalueOf(Objectobj)

      Returns the string representation of theObjectargument.
      Parameters:
      obj- anObject.
      Returns:
      if the argument isnull, then a string equal to"null"; otherwise, the value ofobj.toString()is returned.
      See Also:
      Object.toString()

    • valueOf

      public staticStringvalueOf(char[] data)

      Returns the string representation of thechararray argument. The contents of the character array are copied; subsequent modification of the character array does not affect the newly created string.
      Parameters:
      data- achararray.
      Returns:
      a newly allocated string representing the same sequence of characters contained in the character array argument.

    • valueOf

      public staticStringvalueOf(char[] data, int offset, int count)

      Returns the string representation of a specific subarray of thechararray argument.

      Theoffsetargument is the index of the first character of the subarray. Thecountargument specifies the length of the subarray. The contents of the subarray are copied; subsequent modification of the character array does not affect the newly created string.

      Parameters:
      data- the character array.
      offset- the initial offset into the value of theString.
      count- the length of the value of theString.
      Returns:
      a string representing the sequence of characters contained in the subarray of the character array argument.
      Throws:
      IndexOutOfBoundsException- ifoffsetis negative, orcountis negative, oroffset+countis larger thandata.length.

    • copyValueOf

      public staticStringcopyValueOf(char[] data, int offset, int count)

      Returns a String that represents the character sequence in the array specified.
      Parameters:
      data- the character array.
      offset- initial offset of the subarray.
      count- length of the subarray.
      Returns:
      aStringthat contains the characters of the specified subarray of the character array.

    • copyValueOf

      public staticStringcopyValueOf(char[] data)

      Returns a String that represents the character sequence in the array specified.
      Parameters:
      data- the character array.
      Returns:
      aStringthat contains the characters of the character array.

    • valueOf

      public staticStringvalueOf(boolean b)

      Returns the string representation of thebooleanargument.
      Parameters:
      b- aboolean.
      Returns:
      if the argument istrue, a string equal to"true"is returned; otherwise, a string equal to"false"is returned.

    • valueOf

      public staticStringvalueOf(char c)

      Returns the string representation of thecharargument.
      Parameters:
      c- achar.
      Returns:
      a string of length1containing as its single character the argumentc.

    • valueOf

      public staticStringvalueOf(int i)

      Returns the string representation of theintargument.

      The representation is exactly the one returned by theInteger.toStringmethod of one argument.

      Parameters:
      i- anint.
      Returns:
      a string representation of theintargument.
      See Also:
      Integer.toString(int, int)

    • valueOf

      public staticStringvalueOf(long l)

      Returns the string representation of thelongargument.

      The representation is exactly the one returned by theLong.toStringmethod of one argument.

      Parameters:
      l- along.
      Returns:
      a string representation of thelongargument.
      See Also:
      Long.toString(long)

    • valueOf

      public staticStringvalueOf(float f)

      Returns the string representation of thefloatargument.

      The representation is exactly the one returned by theFloat.toStringmethod of one argument.

      Parameters:
      f- afloat.
      Returns:
      a string representation of thefloatargument.
      See Also:
      Float.toString(float)

    • valueOf

      public staticStringvalueOf(double d)

      Returns the string representation of thedoubleargument.

      The representation is exactly the one returned by theDouble.toStringmethod of one argument.

      Parameters:
      d- adouble.
      Returns:
      a string representation of thedoubleargument.
      See Also:
      Double.toString(double)

    • intern

      publicStringintern()

      Returns a canonical representation for the string object.

      A pool of strings, initially empty, is maintained privately by the classString.

      When the intern method is invoked, if the pool already contains a string equal to thisStringobject as determined by theequals(Object)method, then the string from the pool is returned. Otherwise, thisStringobject is added to the pool and a reference to thisStringobject is returned.

      It follows that for any two stringssandt,s.intern() == t.intern()istrueif and only ifs.equals(t)istrue.

      All literal strings and string-valued constant expressions are interned. String literals are defined in §3.10.5 of theJava Language Specification

      Returns:
      a string that has the same contents as this string, but is guaranteed to be from a pool of unique strings.