Class java.lang.String

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Class java.lang.String

java.lang.Object
   |
   +----java.lang.String

public final class String
extends Object

A general class of objects to represent character strings. Strings are constant, their values cannot be changed after creation. The compiler makes sure that each string constant actually results in a String object. Because string objects are immutable they can be shared. For example:

	String str = "abc";

is equivalent to:

	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(2,1);
	String d = cde.substring(1, 1);

See Also:: StringBuffer
Version:: 1.33, 07 Feb 1995
Author:: Lee Boynton, Arthur van Hoff

String(): Constructs a new empty string.
String(String): Constructs a new string that is a copy of the specified string.
String(char[]): Constructs a new string from an array of characters as its initial value.
String(char[], int, int): Constructs a new string from a sub array of characters.
String(byte[], int, int, int): Constructs a new string from a sub array of bytes.
String(byte[], int): Constructs a new string from an array of bytes.

charAt(int): Returns the character at the specified index.
compareTo(String): Compares this string against another string.
concat(String): Concatenates a string.
copyValueOf(char[], int, int): Returns a string that is equivalent to the given character array.
copyValueOf(char[]): Returns a string that is equivalent to the given character array.
endsWith(String): Determines whether a string ends with some suffix.
equals(Object): Compares a string against another object.
equalsIgnoreCase(Object): Compares the string against another object.
getBytes(int, int, byte[], int): Copies characters from the string into a byte array.
getChars(int, int, char[], int): Copies characters from the string into an character array.
hashCode(): Returns a hashcode of the string.
indexOf(int): Returns the index of the first occurrence of aCharacter.
indexOf(int, int): Returns the index of the first occurrence of ch, starting the search at fromIndex.
indexOf(String): Returns the index of the first occurrence of a substring.
indexOf(String, int): Returns the index of the first occurrence of a substring.
intern(): Returns a string that is equal to the current string bug which is guaranteed to be from the unique string pool.
lastIndexOf(int): Returns the index of the last occurrence of ch in a string.
lastIndexOf(int, int): Returns the index of the last occurrence of ch in a string.
lastIndexOf(String): Returns the index of the last occurrence of a substring.
lastIndexOf(String, int): Returns the index of the last occurrence of a substring.
length(): Returns the length of the string.
regionMatches(int, String, int, int): Determines whether a region of one string matches a region of another string.
regionMatches(boolean, int, String, int, int): Determines whether a region of one string matches a region of another string.
replace(char, char): Converts a string by replacing occurences of oldChar with newChar.
startsWith(String, int): Determines whether a string starts with some prefix.
startsWith(String): Determines whether a string starts with some prefix.
substring(int): Returns the substring of a String.
substring(int, int): Returns the substring of a String.
toCharArray(): Converts to a character array.
toLowerCase(): Converts a string to lower case.
toString(): Converts this string to a string.
toUpperCase(): Converts a string to upper case.
valueOf(Object): Returns a string that represents the string value of the object.
valueOf(char[]): Returns a string that is equivalent to the given character array.
valueOf(char[], int, int): Returns a string that is equivalent to the given character array.
valueOf(boolean): Returns a string object that represents the state of a boolean.
valueOf(int): Returns a string object that represents an integer.
valueOf(long): Returns a string object that represents a long.
valueOf(float): Returns a string object that represents a float.
valueOf(double): Returns a string object that represents a double.

String

  public String()

Constructs a new empty string.

String

  public String(String value)

Constructs a new string that is a copy of the specified string.

Parameters:: value - the initial value of the String

String

  public String(char value[])

Constructs a new string from an array of characters as its initial value. The character array is NOT copied. Do not modify the array after the string is created.

Parameters:: value - the initial value of the String

String

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

Constructs a new string from a sub array of characters. The value of the new string will be count characters starting at offset. The character array is NOT copied. Do not modify the array after the string is created.

Parameters:: value - the initial value of the String, an array of characters; offset - the offset into the value of the string; count - the length of the value of the string

String

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

Constructs a new string from a sub array of bytes. The high-byte of each character can be specified, it should usually be 0. The value of the new string will be count characters starting at offset.

Parameters:: ascii - the bytes that will be converted to characters; hibyte - the high byte of each UNICODE character; offset - the offset into the ascii array; count - the length of the string

String

  public String(byte ascii[],
                int hibyte)

Constructs a new string from an array of bytes. The byte array transformed into UNICODE chars using hibyte as the upper byte of each character.

Parameters:: ascii - the byte that will be converted to characters; hibyte - the top 8 bits of each 16 bit UNICODE character

length

  public int length()

Returns the length of the string. The length of the string is equal to the number of 16 bit UNICODE characters in the string.

Returns:: the length of the string

charAt

  public char charAt(int index)

Returns the character at the specified index. An index ranges from 0 to length() - 1.

Parameters:: index - the index of the desired character
Returns:: the desired character
Throws: StringIndexOutOfRangeException: The index is not in the range 0 to length()-1.

getChars

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

Copies characters from the string into an character array. The characters of the specified substring (determined by srcBegin and srcEnd) are copied into the character array, starting at the array's dstIndex location.

Parameters:: srcBegin - index of the first character in the string; srcEnd - end of the characters that are copied; dst - the destination array; dstBegin - the start offset in the destination array

getBytes

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

Copies characters from the string into a byte array. Copies the characters of the specified substring (determined by srcBegin and srcEnd) into the byte array, starting at the array's dstIndex location.

Parameters:: srcBegin - index of the first character in the string; srcEnd - end of the characters that are copied; dst - the destination array; dstBegin - the start offset in the destination array

equals

  public boolean equals(Object anObject)

Compares a string against another object. Returns true if the object is equal to this string; that is, has the same length and the same characters in the same sequence.

Parameters:: anObject - the object to compare this string against
Returns:: true if they are equal
Overrides:: equals in class Object

equalsIgnoreCase

  public boolean equalsIgnoreCase(Object anObject)

Compares the string against another object. Returns true if the object is equal to this string; that is, has the same length and the same characters in the same sequence. Upper case character are folded to lower case character before they are compared.

Parameters:: anObject - the object to compare this string against
Returns:: true if they are equal, ignoring case

compareTo

  public int compareTo(String anotherString)

Compares this string against another string. Returns an integer that is less than, equal to, or greater than zero, depending on whether this string is less than, equal to, or greater than anotherString.

Returns:: a number less than zero if this string is lexically smaller, 0 if the string is equal or a number greater than 0 if this string is lexically greater.

regionMatches

  public boolean regionMatches(int toffset,
                               String other,
                               int ooffset,
                               int len)

Determines whether a region of one string matches a region of another string.

Parameters:: toffset - where to start looking in this string; other - the other string; ooffset - where to start looking in the other string; len - the number of characters to match
Returns:: true if the region matches with the other

regionMatches

  public boolean regionMatches(boolean ignoreCase,
                               int toffset,
                               String other,
                               int ooffset,
                               int len)

Determines whether a region of one string matches a region of another string. Upper case characters are considered equivalent to lower case letters.

Parameters:: ignoreCase - if true, case is ignored; toffset - where to start looking in this string; other - the other string; ooffset - where to start looking in the other string; len - the number of characters to match
Returns:: true if the region matches with the other

startsWith

  public boolean startsWith(String prefix,
                            int toffset)

Determines whether a string starts with some prefix.

Parameters:: prefix - the prefix; toffset - where to start looking
Returns:: true if the string starts with the prefix

startsWith

  public boolean startsWith(String prefix)

Determines whether a string starts with some prefix.

Parameters:: prefix - the prefix
Returns:: true if the string starts with the prefix

endsWith

  public boolean endsWith(String suffix)

Determines whether a string ends with some suffix.

Parameters:: suffix - the suffix
Returns:: true if the string ends with the suffix

hashCode

  public int hashCode()

Returns a hashcode of the string. This is a large number composed of the character values in the string.

Returns:: the hash code
Overrides:: hashCode in class Object

indexOf

  public int indexOf(int ch)

Returns the index of the first occurrence of aCharacter.

Parameters:: ch - the character
Returns:: the index if the character is found, -1 otherwise

indexOf

  public int indexOf(int ch,
                     int fromIndex)

Returns the index of the first occurrence of ch, starting the search at fromIndex.

Parameters:: ch - the character; fromIndex - the index to start the search from
Returns:: the index if the character is found, -1 otherwise

lastIndexOf

  public int lastIndexOf(int ch)

Returns the index of the last occurrence of ch in a string. The string is searched backwards starting at the last character.

Parameters:: ch - the character
Returns:: the index if the character is found, -1 otherwise

lastIndexOf

  public int lastIndexOf(int ch,
                         int fromIndex)

Returns the index of the last occurrence of ch in a string. The string is searched backwards starting at fromIndex.

Parameters:: ch - the character; fromIndex - the index to start the search from
Returns:: the index if the character is found, -1 otherwise

indexOf

  public int indexOf(String str)

Returns the index of the first occurrence of a substring.

Parameters:: str - the substring
Returns:: the index if the substring is found, -1 otherwise

indexOf

  public int indexOf(String str,
                     int fromIndex)

Returns the index of the first occurrence of a substring. The search is started at fromIndex.

Parameters:: str - the substring; fromIndex - the index to start the search from
Returns:: the index if the substring is found, -1 otherwise

lastIndexOf

  public int lastIndexOf(String str)

Returns the index of the last occurrence of a substring. The string is searched backwards.

Parameters:: str - the substring
Returns:: the index if the substring is found, -1 otherwise

lastIndexOf

  public int lastIndexOf(String str,
                         int fromIndex)

Returns the index of the last occurrence of a substring. The string is searched backwards starting at fromIndex.

Parameters:: str - the substring; fromIndex - the index to start the search from
Returns:: the index if the substring is found, -1 otherwise

substring

  public String substring(int beginIndex)

Returns the substring of a String. The substring is specified by a beginIndex (inclusive) and the end of the string.

Parameters:: beginIndex - begin index, inclusive
Returns:: the substring upto the end of the string

substring

  public String substring(int beginIndex,
                          int endIndex)

Returns the substring of a String. The substring is specified by a beginIndex (inclusive) and an endIndex (exclusive).

Parameters:: beginIndex - begin index, inclusive; endIndex - end index, exclusive
Returns:: the substring

concat

  public String concat(String str)

Concatenates a string.

Parameters:: str - the string which is concatenated to the end of this string
Returns:: the resulting string

replace

  public String replace(char oldChar,
                        char newChar)

Converts a string by replacing occurences of oldChar with newChar.

Parameters:: oldChar - the old character; newChar - the new character
Returns:: the resulting string

toLowerCase

  public String toLowerCase()

Converts a string to lower case.

Returns:: the string, converted to lowercase
See Also:: toLowerCase, toUpperCase

toUpperCase

  public String toUpperCase()

Converts a string to upper case.

Returns:: the string, converted to lowercase
See Also:: toUpperCase, toLowerCase

toString

  public String toString()

Converts this string to a string.

Returns:: the string itself
Overrides:: toString in class Object

toCharArray

  public char toCharArray()

Converts to a character array. This creates a new array.

Returns:: an array of characters

valueOf

  public static String valueOf(Object obj)

Returns a string that represents the string value of the object. The object may choose how to represent itself by implementing a "toString()" method.

Parameters:: obj - the object to be converted
Returns:: the resulting string

valueOf

  public static String valueOf(char data[])

Returns a string that is equivalent to the given character array. Uses the original array as the body of the string (ie. it doesn't copy it to a new array).

Parameters:: data - the character array
Returns:: the resulting string

valueOf

  public static String valueOf(char data[],
                               int offset,
                               int count)

Returns a string that is equivalent to the given character array. Uses the original array as the body of the string (ie. it doesn't copy it to a new array).

Parameters:: data - the character array; offset - the offset into the value of the string; count - the length of the value of the string
Returns:: the resulting string

copyValueOf

  public static String copyValueOf(char data[],
                                   int offset,
                                   int count)

Returns a string that is equivalent to the given character array. It creates a new array and copies the characters into it.

Parameters:: data - the character array; offset - the offset into the value of the string; count - the length of the value of the string
Returns:: the resulting string

copyValueOf

  public static String copyValueOf(char data[])

Returns a string that is equivalent to the given character array. It creates a new array and copies the characters into it.

Parameters:: data - the character array
Returns:: the resulting string

valueOf

  public static String valueOf(boolean b)

Returns a string object that represents the state of a boolean.

Parameters:: b - the boolean
Returns:: the resulting string

valueOf

  public static String valueOf(int i)

Returns a string object that represents an integer.

Parameters:: i - the integer
Returns:: the resulting string

valueOf

  public static String valueOf(long l)

Returns a string object that represents a long.

Parameters:: l - the long
Returns:: the resulting string

valueOf

  public static String valueOf(float f)

Returns a string object that represents a float.

Parameters:: f - the float
Returns:: the resulting string

valueOf

  public static String valueOf(double d)

Returns a string object that represents a double.

Parameters:: d - the double
Returns:: the resulting string

intern

  public String intern()

Returns a string that is equal to the current string bug which is guaranteed to be from the unique string pool. s1.intern() == s2.intern() <=> s1.equals(s2).

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