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§1.16 Class String
public final class java.lang.String
extends java.lang.Object (I-§1.12)
{
// Constructors
public String(); §1.16.1
public String(byte ascii[], int hibyte); §1.16.2
public String(byte ascii[], int hibyte, §1.16.3
int offset, int count);
public String(char value[]); §1.16.4
public String(char value[], int offset, int count); §1.16.5
public String(String value); §1.16.6
public String(StringBuffer buffer); §1.16.7
// Methods
public char charAt(int index); §1.16.8
public int compareTo(String anotherString); §1.16.9
public String concat(String str); §1.16.10
public static String copyValueOf(char data[]); §1.16.11
public static String §1.16.12
copyValueOf(char data[], int offset, int count);
public boolean endsWith(String suffix); §1.16.13
public boolean equals(Object anObject); §1.16.14
public boolean equalsIgnoreCase(String anotherString); §1.16.15
public void getBytes(int srcBegin, int srcEnd, §1.16.16
byte dst[], int dstBegin);
public void getChars(int srcBegin, int srcEnd, §1.16.17
char dst[], int dstBegin);
public int hashCode(); §1.16.18
public int indexOf(int ch); §1.16.19
public int indexOf(int ch, int fromIndex); §1.16.20
public int indexOf(String str); §1.16.21
public int indexOf(String str, int fromIndex); §1.16.22
public String intern(); §1.16.23
public int lastIndexOf(int ch); §1.16.24
public int lastIndexOf(int ch, int fromIndex); §1.16.25
public int lastIndexOf(String str); §1.16.26
public int lastIndexOf(String str, int fromIndex); §1.16.27
public int length(); §1.16.28
public boolean regionMatches(boolean ignoreCase, §1.16.29
int toffset, String other, int ooffset, int len);
public boolean regionMatches(int toffset, String other, §1.16.30
int ooffset, int len);
public String replace(char oldChar, §1.16.31
char newChar);
public boolean startsWith(String prefix); §1.16.32
public boolean startsWith(String prefix, int toffset); §1.16.33
public String substring(int beginIndex); §1.16.34
public String substring(int beginIndex, int endIndex); §1.16.35
public char[] toCharArray(); §1.16.36
public String toLowerCase(); §1.16.37
public String toString(); §1.16.38
public String toUpperCase(); §1.16.39
public String trim(); §1.16.40
public static String valueOf(boolean b); §1.16.41
public static String valueOf(char c); §1.16.42
public static String valueOf(char data[]); §1.16.43
public static String §1.16.44
valueOf(char data[], int offset, int count);
public static String valueOf(double d); §1.16.45
public static String valueOf(float f); §1.16.46
public static String valueOf(int i); §1.16.47
public static String valueOf(long l); §1.16.48
public static String valueOf(Object obj); §1.16.49
}
The String class represents character strings. All string literals in Java programs, such as
"abc" are implemented as instances of this class.
Strings are constant, their values cannot be changed after they are created. String buffers
(I-§1.17) support mutable strings.
The class String includes methods for examining individual characters of the sequence, for
comparing strings, for searching strings, for extracting substrings, and for creating a copy
of a string with all characters translated to uppercase or to lowercase.
String
public String()
- Allocates a new String containing no characters.
String
public String(byte ascii[], int hibyte)
- Allocates a new String containg characters constructed from an array of 8-
bit integer values. Each character c in the resulting string is constructed
from the corresponding component b in 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 character
String
public String(byte ascii[], int hibyte, int offset,
int count)
- Allocates a new String constructed from a subarray of an array of 8-bit integer values.
- The offset argument is the index of the first byte of the subarray, and the
count argument specifies the length of the subarray.
- Each byte in the subarray is converted to a char as specified in the method
above (I-§1.16.2).
- Parameters:
ascii
-
the bytes to be converted to characters
hibyte
-
the top 8 bits of each 16-bit Unicode character
-
offset
-
the initial offset
count
-
the length
- Throws
- StringIndexOutOfBoundsException (I-§1.44)
- If the offset or count argument is invalid.
String
public String(char value[])
- Allocates a new String so that it represents the sequence of characters currently contained in the character array argument.
- Parameters:
value
-
the initial value of the string
String
public String(char value[], int offset, int count)
- Allocates a new String that contains characters from a subarray of the character array argument. The offset argument is the index of the first character
of the subarray and the count argument specifies the length of the subarray.
- Parameters:
value
-
array that is the source of characters
offset
-
the initial offset
count
-
the length
- Throws
- StringIndexOutOfBoundsException (I-§1.44)
- If the offset and count arguments index characters outside the bounds of
the value array.
String
public String(String value)
- Allocates a new string that contains the same sequence of characters as the
string argument.
- Parameters:
value
-
a String.
String
public String(StringBuffer buffer)
- Allocates a new string that contains the sequence of characters currently
contained in the string buffer argument.
- Parameters:
buffer
-
a StringBuffer.
charAt
public char charAt(int index)
- Returns:
- The character at the specified index of this string. The first character is
at index 0.
- Parameters:
index
-
the index of the desired character
- Throws
- StringIndexOutOfBoundsException (I-§1.44)
- If the index is out of range.
compareTo
public int compareTo(String anotherString)
- Compares two strings lexicographically.
- Parameters:
anotherString
-
the String to be compared
- Returns:
- The value 0 if the argument string is equal to this string; a value less
than 0 if this string is lexicographically less than the string argument;
and a value greater than 0 if this string is lexicographically greater
than the string argument.
concat
public String concat(String str)
- Concatenates the string argument to the end of this string.
- If the length of the argument string is zero, then this object is returned.
- Parameters:
str
-
the String which is concatenated to the end of this String
- Returns:
- A string that represents the concatenation of this object's characters
followed by the string argument's characters.
copyValueOf
public static String copyValueOf(char data[])
- Returns:
- a String that contains the characters of the character array.
- Parameters:
data
-
the character array
copyValueOf
public static String
copyValueOf(char data[], int offset, int count)
- Parameters:
data
-
the character array
offset
-
initial offset of the subarray
count
-
length of the subarray
- Returns:
- a String that contains the characters of the specified subarray of the
character array.
-
endsWith
public boolean endsWith(String suffix)
- Parameters:
suffix
-
the suffix
- Returns:
- true if the character sequence represented by the argument is a
suffix of the character sequence represented by this object; false
otherwise.
equals
public boolean equals(Object anObject)
- The result is true if and only if the argument is not null and is a String object
that represents the same sequence of characters as this object.
- Parameters:
anObject
-
the object to compare this String against
- Returns:
- true if the String's are equal; false otherwise.
- Overrides:
- equals in class Object (I-§1.12.3).
- See Also:
- equalsIgnoreCase (I-§1.16.15)
- compareTo (I-§1.16.9).
equalsIgnoreCase
public boolean equalsIgnoreCase(String anotherString)
- The result is true if and only if the argument is not null and is a String object
that represents the same sequence of characters as this object, where case
is ignored.
- Two characters are considered the same, ignoring case, if at least one of
the following is true:
- Two sequence of characters are the same, ignoring case, if the sequences
have the same length and corresponding characters are the same, ignoring
case.
- Parameters:
anotherString
-
the String to compare this String against
- Returns:
- true if the String's are equal, ignoring case; false otherwise.
getBytes
public void getBytes(int srcBegin, int srcEnd,
byte dst[], int dstBegin)
- Copies characters from this string into the destination byte array. Each
byte receives the 8 low-order bits of the corresponding character.
- The first character to be copied is at index srcBegin; the last character to be
copied is at index srcEnd-1. The total number of characters to be copied is
srcEnd-srcBegin. The characters, converted to bytes, are copied into the subarray of dst starting at index dstBegin and 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
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 index srcBegin; the last character to be
copied is at index srcEnd-1 (thus the total number of characters to be copied
is srcEnd-srcBegin). The characters are copied into the subarray of dst starting
at index dstBegin and 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
hashCode
public int hashCode()
- Returns:
- a hash code value for this object.
- Overrides:
- hashCode in class Object (I-§1.12.6).
indexOf
public int indexOf(int ch)
- Parameters:
ch
-
a character
- Returns:
- the index of the first occurrence of the character in the character
sequence represented by this object, or -1 if the character does not
occur.
indexOf
public int indexOf(int ch, int fromIndex)
- Parameters:
ch
-
a character
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 to fromIndex, or -1 if the character does not occur.
indexOf
public int indexOf(String str)
- Parameters:
str
-
any string
- Returns:
- if the string argument occurs as a substring within this object, then the
index of the first character of the first such substring is returned; if it
does not occur as a substring, -1 is returned.
-
indexOf
public int indexOf(String str, int fromIndex)
- Parameters:
str
-
the substring to search for
fromIndex
-
the index to start the search from
- Returns:
- If the string argument occurs as a substring within this object at a
starting index no smaller than fromIndex then the index of the first character of the first such substring is returned. If it does not occur as a
substring starting at fromIndex or beyond, -1 is returned.
intern
public String intern()
- Creates a canonical representation for the string object.
- If s and t are strings such that s.equals(t), it is guaranteed that
s.intern() == t.intern().
- Returns:
- a string that has the same contents as this string, but is guaranteed to
be from a pool of unique strings.
lastIndexOf
public int lastIndexOf(int ch)
- Parameters:
ch
-
a character.
- Returns:
- the index of the last occurrence of the character in the character
sequence represented by this object, or -1 if the character does not
occur.
lastIndexOf
public int lastIndexOf(int ch, int fromIndex)
- Parameters:
ch
-
a character
fromIndex
-
the index to start the search from
- Returns:
- the index of the last occurrence of the character in the character
sequence represented by this object that is less than or equal to from-Index, or -1 if the character does not occur before that point.
lastIndexOf
public int lastIndexOf(String str)
- Parameters:
str
-
the substring to search for
- Returns:
- If the string argument occurs as a substring within this object, then the
index of the first character of the last such substring is returned. If it
does not occur as a substring, -1 is returned.
-
lastIndexOf
public int lastIndexOf(String str, int fromIndex)
- Parameters:
str
-
the substring to search for
fromIndex
-
the index to start the search from
- Returns:
- If the string argument occurs as a substring within this object at a
starting index no greater than fromIndex then the index of the first character of the lastsuch substring is returned. If it does not occur as a substring starting at fromIndex or earlier, -1 is returned.
length
public int length()
- Returns:
- the length of the sequence of characters represented by this object is
returned.
regionMatches
public boolean
regionMatches(boolean ignoreCase, int toffset,
String other, int ooffset, int len)
- Determines if two string regions are equal.
- If toffset or ooffset is negative, or if toffset+length is greater than the length of
this string, or if ooffset+length is greater than the length of the string argument, then this
method returns false.
- Parameters:
ignoreCase
-
if true, ignore case when comparing characters
toffset
-
starting offset of the subregion in this string
other
-
string argument
ooffset
-
starting offset of the subregion in the string argument
len
-
the number of characters to compare
- Returns:
- true if the specified subregion of this string matches the specified subregion of the string argument; false otherwise. Whether the matching is
exact or case insensitive depends on the ignoreCase argument.
regionMatches
public boolean
regionMatches(int toffset, String other,
int ooffset, int len)
- Determines if two string regions are equal.
- If toffset or ooffset is negative, or if toffset+length is greater than the length of
this string, or if ooffset+length is greater than the length of the string argument, then this method returns false.
- Parameters:
toffset
-
starting offset of the subregion in this string
other
-
string argument
ooffset
-
starting offset of the subregion in the string argument
len
-
the number of characters to compare
- Returns:
- true if the specified subregion of this string exactly matches the specified subregion of the string argument; false otherwise.
replace
public String replace(char oldChar, char newChar)
- Returns a new string resulting from replacing all occurrences of oldChar in
this string with newChar.
- If the character oldChar does not occur in the character sequence represented by this object, then this string is returned.
- Parameters:
oldChar
-
the old character
newChar
-
the new character
- Returns:
- a string derived from this string by replacing every occurrence of oldChar with newChar.
startsWith
public boolean startsWith(String prefix)
- Parameters:
prefix
-
the prefix
- Returns:
- true if the character sequence represented by the argument is a prefix
of the character sequence represented by this string; false otherwise
startsWith
public boolean startsWith(String prefix, int toffset)
- Parameters:
prefix
-
the prefix
toffset
-
where to begin looking in the the String
- Returns:
- true if the character sequence represented by the argument is a prefix of
the substring of this object starting at index toffset; false otherwise
substring
public String substring(int beginIndex)
- Creates a new string that is a substring of this string. The substring begins
at the specified index and extends to the end of this string.
- Parameters:
beginIndex
-
the beginning index, inclusive
- Returns:
- the specified substring.
- Throws
- StringIndexOutOfBoundsException (I-§1.44)
- If the beginIndex is out of range.
substring
public String substring(int beginIndex, int endIndex)
- Creates a new string that is a substring of this string. The substring begins
at the specified beginIndex and extends to the character at index endIndex - 1.
- Parameters:
beginIndex
-
the beginning index, inclusive
endIndex
-
the ending index, exclusive
- Returns:
- the specified substring.
- Throws
- StringIndexOutOfBoundsException (I-§1.44)
- If the beginIndex or the endIndex is out of range.
toCharArray
public char[] toCharArray()
- Returns:
- A newly allocated character array whose length is the length of this
string and whose contents is initialized to contain the character
sequence represented by this string.
toLowerCase
public String toLowerCase()
- Converts a string to lowercase.
- If no character in this string has a different lowercase version (I-§1.2.21),
then this string is returned.
- Otherwise, a new string is allocated, whose length is identical to this
string, and such that each character which has a difference lowercase version is mapped to this lower case equivalent.
- Returns:
- the string, converted to lowercase.
toString
public String toString()
- This object (which is already a string!) is itself returned.
- Returns:
- the string itself.
- Overrides:
- toString in class Object (I-§1.12.9).
toUpperCase
public String toUpperCase()
- Converts a string to uppercase.
- If no character in this string has a different uppercase version (I-§1.2.24),
then this string is returned.
- Otherwise, a new string is allocated, whose length is identical to this
string, and such that each character which has a difference uppercase version is mapped to this uppercase equivalent.
- Returns:
- the string, converted to uppercase.
trim
public String trim()
- Removes white space from both ends of a string.
- All characters that have codes less than or equal to '\u0020' (the space character) are considered to be white space.
- Returns:
- this string, with whitespace removed from the front and end
valueOf
public static String valueOf(boolean b)
- Creates the string representation of the boolean argument.
- Parameters:
b
-
a boolean
- Returns:
- if the argument is true, a string equal to "true" is returned; otherwise, a
string equal to "false" is returned.
valueOf
public static String valueOf(char c)
- Creates the string representation of the char argument.
- Parameters:
c
-
a char
- Returns:
- a newly allocated string of length one containing as its single characer
the argument c.
valueOf
public static String valueOf(char data[])
- Creates the string representation of the char array argument.
- Parameters:
data
-
a char array
- Returns:
- a newly allocated string representing the same sequence of characters
contained in the character array argument.
valueOf
public static String
valueOf(char data[], int offset, int count)
- Creates the string representation of a specific subarray of the char array
argument.
- The offset argument is the index of the first character of the subarray. The
count argument specifies the length of the subarray.
- Parameters:
data
-
the character array
offset
-
the initial offset into the value of the String
count
-
the length of the value of the String
- Returns:
- a newly allocated string representing the sequence of characters contained in the subarray of the character array argument.
valueOf
public static String valueOf(double d)
- Creates the string representation of the double argument.
- The representation is exactly the one returned by the Double-.toString method
of one argument (I-§1.6.21).
- Parameters:
d
-
a double
- Returns:
- a newly allocated string containing a string representation of the double
argument.
valueOf
public static String valueOf(float f)
- Creates the string representation of the float argument.
- The representation is exactly the one returned by the Float.toString method
of one argument (I-§1.7.22).
- Parameters:
f
-
a float
- Returns:
- a newly allocated string containing a string representation of the float
argument.
valueOf
public static String valueOf(int i)
- Creates the string representation of the int argument.
- The representation is exactly the one returned by the Integer.toString method
of one argument (I-§1.8.20).
- Parameters:
i
-
an int
- Returns:
- a newly allocated string containing a string representation of the int
argument.
valueOf
public static String valueOf(long l)
- Creates the string representation of a the long argument.
- The representation is exactly the one returned by the Long.toString method
of one argument (I-§1.9.20).
- Parameters:
l
-
a long
- Returns:
- a newly allocated string containing a string representation of the long
argument.
valueOf
public static String valueOf(Object obj)
- Creates the string representation of the Object argument.
- Parameters:
obj
-
an Object.
- Returns:
- If the argument is null, then a string equal to "null"; otherwise the value
of obj.toString() is returned.
- See Also:
- toString in class Object (I-§1.12.9).
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Java API Document (HTML generated by dkramer on April 22, 1996)
Copyright © 1996 Sun Microsystems, Inc.
All rights reserved
Please send any comments or corrections to doug.kramer@sun.com