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java.lang.Object | +----java.lang.String
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 support mutable strings. 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(2,3);
String d = cde.substring(1, 2);
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.
The Java language provides special support for the string
concatentation operator ( + ), and for conversion of
other objects to strings. String concatenation is implemented
through the StringBuffer class and its
append method.
String conversions are implemented through the method
toString, defined by Object and
inherited by all classes in Java. For additional information on
string concatenation and conversion, see Gosling, Joy, and Steele,
The Java Language Specification.
String()
String containing no characters.
String(byte[])
String by converting the specified array
of bytes using the platform's default character encoding.
String(byte[], int)
String containing characters
constructed from an array of 8-bit integer values.
Deprecated.
String(byte[], int, int)
String by converting the specified
subarray of bytes using the platform's default character encoding.
String(byte[], int, int, int)
String constructed from a subarray
of an array of 8-bit integer values.
Deprecated.
String(byte[], int, int, String)
String by converting the specified
subarray of bytes using the specified character encoding.
String(byte[], String)
String by converting the specified array
of bytes using the specified character encoding.
String(char[])
String so that it represents the
sequence of characters currently contained in the character array
argument.
String(char[], int, int)
String that contains characters from
a subarray of the character array argument.
String(String)
String(StringBuffer)
charAt(int)
compareTo(String)
concat(String)
copyValueOf(char[])
copyValueOf(char[], int, int)
endsWith(String)
equals(Object)
equalsIgnoreCase(String)
getBytes()
String into bytes according to the platform's
default character encoding, storing the result into a new byte array.
getBytes(int, int, byte[], int)
getBytes(String)
String into bytes according to the specified
character encoding, storing the result into a new byte array.
getChars(int, int, char[], int)
hashCode()
indexOf(int)
indexOf(int, int)
indexOf(String)
indexOf(String, int)
intern()
lastIndexOf(int)
lastIndexOf(int, int)
lastIndexOf(String)
lastIndexOf(String, int)
length()
regionMatches(boolean, int, String, int, int)
regionMatches(int, String, int, int)
replace(char, char)
oldChar in this string with newChar.
startsWith(String)
startsWith(String, int)
substring(int)
substring(int, int)
toCharArray()
toLowerCase()
String to lowercase.
toLowerCase(Locale)
String to lower
case using the rules of the given locale.
toString()
toUpperCase()
toUpperCase(Locale)
String to upper
case using the rules of the given locale.
trim()
valueOf(boolean)
boolean argument.
valueOf(char)
char argument.
valueOf(char[])
char array
argument.
valueOf(char[], int, int)
char array argument.
valueOf(double)
double argument.
valueOf(float)
float argument.
valueOf(int)
int argument.
valueOf(long)
long argument.
valueOf(Object)
Object argument.
String
public String()
String containing no characters.
String
public String(String value)
String.
String
public String(char value[])
String so that it represents the
sequence of characters currently contained in the character array
argument.
String
public String(char value[],
int offset,
int count)
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.
offset
and count arguments index characters outside
the bounds of the value array.
String
public String(byte ascii[],
int hibyte,
int offset,
int count)
String constructors that take a character-encoding name or
that use the platform's default encoding.
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.
offset
or count argument is invalid.
String
public String(byte ascii[],
int hibyte)
String constructors that take a character-encoding name or
that use the platform's default encoding.
String containing characters
constructed from an array of 8-bit integer values. Each character
cin the resulting string is constructed from the
corresponding component b in the byte array such that:
c == (char)(((hibyte & 0xff) << 8)
| (b & 0xff))
String
public String(byte bytes[],
int offset,
int length,
String enc) throws UnsupportedEncodingException
String by converting the specified
subarray of bytes using the specified character encoding. The length of
the new String is a function of the encoding, and hence may
not be equal to the length of the subarray.
String
public String(byte bytes[],
String enc) throws UnsupportedEncodingException
String by converting the specified array
of bytes using the specified character encoding. The length of the new
String is a function of the encoding, and hence may not be
equal to the length of the byte array.
String
public String(byte bytes[],
int offset,
int length)
String by converting the specified
subarray of bytes using the platform's default character encoding. The
length of the new String is a function of the encoding, and
hence may not be equal to the length of the subarray.
String
public String(byte bytes[])
String by converting the specified array
of bytes using the platform's default character encoding. The length of
the new String is a function of the encoding, and hence may
not be equal to the length of the byte array.
String
public String(StringBuffer buffer)
StringBuffer.
length
public int length()
charAt
public char charAt(int index)
0 to length() - 1.
0.
getChars
public void getChars(int srcBegin,
int srcEnd,
char dst[],
int dstBegin)
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
getBytes
public void getBytes(int srcBegin,
int srcEnd,
byte dst[],
int dstBegin)
getBytes(String enc) method, which takes a
character-encoding name, or the getBytes() method, which
uses the platform's default encoding.
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
getBytes
public byte[] getBytes(String enc) throws UnsupportedEncodingException
String into bytes according to the specified
character encoding, storing the result into a new byte array.
getBytes
public byte[] getBytes()
String into bytes according to the platform's
default character encoding, storing the result into a new byte array.
equals
public boolean equals(Object anObject)
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.
String
against.
true if the String are equal;
false otherwise.
equalsIgnoreCase
public boolean equalsIgnoreCase(String anotherString)
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:
==
operator).
Character.toUppercase to each
character produces the same result.
Character.toLowercase to each
character produces the same result.
Two sequences of characters are the same, ignoring case, if the sequences have the same length and corresponding characters are the same, ignoring case.
String to compare this
String against.
true if the Strings are equal,
ignoring case; false otherwise.
compareTo
public int compareTo(String anotherString)
String to be compared.
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.
regionMatches
public boolean regionMatches(int toffset,
String other,
int ooffset,
int len)
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.
true if the specified subregion of this string
exactly matches the specified subregion of the string argument;
false otherwise.
regionMatches
public boolean regionMatches(boolean ignoreCase,
int toffset,
String other,
int ooffset,
int len)
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.
true, ignore case when comparing
characters.
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.
startsWith
public boolean startsWith(String prefix,
int toffset)
true if the character sequence represented by the
argument is a prefix of the substring of this object starting
at index toffset; false otherwise.
startsWith
public boolean startsWith(String prefix)
true if the character sequence represented by the
argument is a prefix of the character sequence represented by
this string; false otherwise.
endsWith
public boolean endsWith(String suffix)
true if the character sequence represented by the
argument is a suffix of the character sequence represented by
this object; false otherwise.
hashCode
public int hashCode()
indexOf
public int indexOf(int ch)
-1 if the character does not occur.
indexOf
public int indexOf(int ch,
int fromIndex)
fromIndex, or -1
if the character does not occur.
lastIndexOf
public int lastIndexOf(int ch)
-1 if the character does not occur.
lastIndexOf
public int lastIndexOf(int ch,
int fromIndex)
fromIndex, or -1
if the character does not occur before that point.
indexOf
public int indexOf(String str)
-1 is returned.
indexOf
public int indexOf(String str,
int fromIndex)
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.
lastIndexOf
public int lastIndexOf(String str)
this.length().
-1 is returned.
lastIndexOf
public int lastIndexOf(String str,
int fromIndex)
fromIndex.
fromIndex, then the index of the first character of
the last such substring is returned. If it does not occur as a
substring starting at fromIndex or earlier,
-1 is returned.
substring
public String substring(int beginIndex)
beginIndex is out of range.
substring
public String substring(int beginIndex,
int endIndex)
beginIndex and
extends to the character at index endIndex - 1.
beginIndex or the endIndex is
out of range.
concat
public String concat(String str)
If the length of the argument string is 0, then this
object is returned.
String that is concatenated to the end
of this String.
replace
public String replace(char oldChar,
char newChar)
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.
oldChar with newChar.
toLowerCase
public String toLowerCase(Locale locale)
String to lower
case using the rules of the given locale.
toLowerCase
public String toLowerCase()
String to lowercase.
If no character in the string has a different lowercase version,
based on calling the toLowerCase method defined by
Character, then the original string is returned.
Otherwise, a new string is allocated, whose length is identical to this string, and such that each character that has a different lowercase version is mapped to this lowercase equivalent.
toUpperCase
public String toUpperCase(Locale locale)
String to upper
case using the rules of the given locale.
toUpperCase
public String toUpperCase()
If no character in this string has a different uppercase version,
based on calling the toUpperCase method defined by
Character, then the original string is returned.
Otherwise, a new string is allocated, whose length is identical to this string, and such that each character that has a different uppercase version is mapped to this uppercase equivalent.
trim
public String trim()
All characters that have codes less than or equal to
'\u0020' (the space character) are considered to be
white space.
toString
public String toString()
toCharArray
public char[] toCharArray()
valueOf
public static String valueOf(Object obj)
Object argument.
Object.
null, then a string equal to
"null"; otherwise, the value of
obj.toString() is returned.
valueOf
public static String valueOf(char data[])
char array
argument.
char array.
valueOf
public static String valueOf(char data[],
int offset,
int count)
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.
String.
String.
copyValueOf
public static String copyValueOf(char data[],
int offset,
int count)
String that contains the characters of the
specified subarray of the character array.
copyValueOf
public static String copyValueOf(char data[])
String that contains the characters of the
character array.
valueOf
public static String valueOf(boolean b)
boolean argument.
boolean.
true, a string equal to
"true" is returned; otherwise, a string equal to
"false" is returned.
valueOf
public static String valueOf(char c)
char argument.
char.
1 containing
as its single character the argument c.
valueOf
public static String valueOf(int i)
int argument.
The representation is exactly the one returned by the
Integer.toString method of one argument.
int.
int argument.
valueOf
public static String valueOf(long l)
long argument.
The representation is exactly the one returned by the
Long.toString method of one argument.
long.
long argument.
valueOf
public static String valueOf(float f)
float argument.
The representation is exactly the one returned by the
Float.toString method of one argument.
float.
float argument.
valueOf
public static String valueOf(double d)
double argument.
The representation is exactly the one returned by the
Double.toString method of one argument.
double.
double argument.
intern
public native String intern()
If s and t are strings such that
s.equals(t), it is guaranteed that
s.intern() == t.intern().
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