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Class

Java™ Platform
Standard Ed. 6

SUMMARY: NESTED | FIELD |  | 

DETAIL: FIELD |  | 

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java.lang
Class StringBuffer

 java.lang.StringBuffer

All Implemented Interfaces:

,  , 

---

public final class StringBuffer

extends  implements  , 

A thread-safe(线程安全), mutable sequence of characters. A string buffer（缓冲区） is like a , but can be modified（修改）. At any point in time it contains some(某些) particular（特定的） sequence of characters, but the length and content of the sequence can be changed through certain（某些） method calls.

String buffers are safe for use by multiple threads(多线程). The methods are synchronized(同步) where necessary(必要) so that(所以) all the operations（操作） on any particular(特定) instance behave as(像) if they occur(发生) in some serial(串行的) order（序列） that is consistent with（一致） the order(顺序) of the method calls(调用方法) made by each of the individual(每个独立的) threads involved(涉及的).

The principal(最重要的) operations on a StringBuffer are the append and insert methods, which are overloaded（重载） so as to accept data(接受数据) of any type. Each effectively(有效的) converts a given(给定的) datum(数据) to a string and then appends or inserts the characters of that string to the string buffer. The append method always adds these characters at the end(末端) of the buffer; the insert method adds the characters at a specified point.

For example, if z refers(属于) to a string buffer object whose current contents are "start", then the method call z.append("le") would cause the string buffer to contain "startle", whereas(反之)z.insert(4, "le") would alter the string buffer to contain "starlet".

In general(情况下), if sb refers to an instance of a StringBuffer, then sb.append(x) has the same effect(效果) as sb.insert(sb.length(), x).

Whenever an operation occurs involving(有关的) a source sequence (such as appending or inserting from a source sequence) this class synchronizes(同步) only on the string buffer performing(执行) the operation, not on the source.

Every string buffer has a capacity(容量). As long as the length of the character sequence contained in the string buffer does not exceed(超过) the capacity, it is not necessary toallocate(分配) a new internal(内部) buffer array. If the internal buffer overflows(溢出), it is automatically(自动的) made larger(增大). As of release(发布) JDK 5, this class has been supplemented(增加) with an equivalent class(等价类) designed for use by a single thread, . The StringBuilder class should generally(一般) be used in preference(优先) to this one, as it supports all of the same operations but it is faster(更快的), as it performs(执行) no synchronization.

Since:

JDK1.0

See Also:

,  , 

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Constructor Summary

()
Constructs a string buffer with no characters in it and an initial capacity of 16 characters.

( seq)
Constructs a string buffer that contains the same characters as the specifiedCharSequence.

(int capacity)
Constructs a string buffer with no characters in it and the specified initial capacity.

( str)
Constructs a string buffer initialized to the contents of the specified string.

Method Summary
	(boolean b) Appends the string representation of the boolean argument to the sequence.
	(char c) Appends the string representation of the char argument to this sequence.
	(char[] str) Appends the string representation of the char array argument to this sequence.
	(char[] str, int offset, int len) Appends the string representation of a subarray of the char array argument to this sequence.
	( s) Appends the specified CharSequence to this sequence.
	( s, int start, int end) Appends a subsequence of the specified CharSequence to this sequence.
	(double d) Appends the string representation of the double argument to this sequence.
	(float f) Appends the string representation of the float argument to this sequence.
	(int i) Appends the string representation of the int argument to this sequence.
	(long lng) Appends the string representation of the long argument to this sequence.
	( obj) Appends the string representation of the Object argument.
	( str) Appends the specified string to this character sequence.
	( sb) Appends the specified StringBuffer to this sequence.
	(int codePoint) Appends the string representation of the codePoint argument to this sequence.
int	() Returns the current capacity.
char	(int index) Returns the char value in this sequence at the specified index.
int	(int index) Returns the character (Unicode code point) at the specified index.
int	(int index) Returns the character (Unicode code point) before the specified index.
int	(int beginIndex, int endIndex) Returns the number of Unicode code points in the specified text range of this sequence.
	(int start, int end) Removes the characters in a substring of this sequence.
	(int index) Removes the char at the specified position in this sequence.
void	(int minimumCapacity) Ensures that the capacity is at least equal to the specified minimum.
void	(int srcBegin, int srcEnd, char[] dst, int dstBegin) Characters are copied from this sequence into the destination character array dst.
int	( str) Returns the index within this string of the first occurrence of the specified substring.
int	( str, int fromIndex) Returns the index within this string of the first occurrence of the specified substring, starting at the specified index.
	(int offset, boolean b) Inserts the string representation of the boolean argument into this sequence.
	(int offset, char c) Inserts the string representation of the char argument into this sequence.
	(int offset, char[] str) Inserts the string representation of the char array argument into this sequence.
	(int index, char[] str, int offset, int len) Inserts the string representation of a subarray of the str array argument into this sequence.
	(int dstOffset,  s) Inserts the specified CharSequence into this sequence.
	(int dstOffset,  s, int start, int end) Inserts a subsequence of the specified CharSequence into this sequence.
	(int offset, double d) Inserts the string representation of the double argument into this sequence.
	(int offset, float f) Inserts the string representation of the float argument into this sequence.
	(int offset, int i) Inserts the string representation of the second int argument into this sequence.
	(int offset, long l) Inserts the string representation of the long argument into this sequence.
	(int offset,  obj) Inserts the string representation of the Object argument into this character sequence.
	(int offset,  str) Inserts the string into this character sequence.
int	( str) Returns the index within this string of the rightmost occurrence of the specified substring.
int	( str, int fromIndex) Returns the index within this string of the last occurrence of the specified substring.
int	() Returns the length (character count).
int	(int index, int codePointOffset) Returns the index within this sequence that is offset from the given indexby codePointOffset code points.
	(int start, int end,  str) Replaces the characters in a substring of this sequence with characters in the specified String.
	() Causes this character sequence to be replaced by the reverse of the sequence.
void	(int index, char ch) The character at the specified index is set to ch.
void	(int newLength) Sets the length of the character sequence.
	(int start, int end) Returns a new character sequence that is a subsequence of this sequence.
	(int start) Returns a new String that contains a subsequence of characters currently contained in this character sequence.
	(int start, int end) Returns a new String that contains a subsequence of characters currently contained in this sequence.
	() Returns a string representing the data in this sequence.
void	() Attempts to reduce storage used for the character sequence.

Methods inherited from class java.lang.

, , , , , , , , , 

Constructor Detail

StringBuffer

public StringBuffer()

Constructs a string buffer with no characters in it and an initial capacity of 16 characters.

---

StringBuffer

public StringBuffer(int capacity)

Constructs a string buffer with no characters in it and the specified initial capacity.

Parameters:

capacity - the initial capacity.

Throws:

 - if the 

capacity argument is less than 

0.

---

StringBuffer

public StringBuffer( str)

Constructs a string buffer initialized to the contents of the specified string. The initial capacity of the string buffer is 

16 plus the length of the string argument.

Parameters:

str - the initial contents of the buffer.

Throws:

 - if 

str is 

null

---

StringBuffer

public StringBuffer( seq)

Constructs a string buffer that contains the same characters as the specified

CharSequence. The initial capacity of the string buffer is 

16 plus the length of the 

CharSequence argument.

If the length of the specified CharSequence is less than or equal to zero, then an empty buffer of capacity 16 is returned.

Parameters:

seq - the sequence to copy.

Throws:

 - if 

seq is 

null

Since:

1.5

Method Detail

length

public int length()

Returns the length (character count).

Specified by:

 in interface 

Returns:

the length of the sequence of characters currently represented by this object

---

capacity

public int capacity()

Returns the current capacity. The capacity is the amount of storage available for newly inserted characters, beyond which an allocation will occur.

Returns:

the current capacity

---

ensureCapacity

public void ensureCapacity(int minimumCapacity)

Ensures that the capacity is at least equal to the specified minimum. If the current capacity is less than the argument, then a new internal array is allocated with greater capacity. The new capacity is the larger of:

• The minimumCapacity argument.
• Twice the old capacity, plus 2.

If the 

minimumCapacity argument is nonpositive, this method takes no action and simply returns.

Parameters:

minimumCapacity - the minimum desired capacity.

---

trimToSize

public void trimToSize()

Attempts to reduce storage used for the character sequence. If the buffer is larger than necessary to hold its current sequence of characters, then it may be resized to become more space efficient. Calling this method may, but is not required to, affect the value returned by a subsequent call to the   method.

Since:

1.5

---

setLength

public void setLength(int newLength)

Sets the length of the character sequence. The sequence is changed to a new character sequence whose length is specified by the argument. For every nonnegative index 

k less than 

newLength, the character at index 

k in the new character sequence is the same as the character at index 

k in the old sequence if 

k is less than the length of the old character sequence; otherwise, it is the null character 

'\u0000'. In other words, if the 

newLength argument is less than the current length, the length is changed to the specified length.

If the newLength argument is greater than or equal to the current length, sufficient null characters ('\u0000') are appended so that length becomes thenewLength argument.

The newLength argument must be greater than or equal to 0.

Parameters:

newLength - the new length

Throws:

 - if the 

newLength argument is negative.

See Also:

---

charAt

public char charAt(int index)

Returns the 

char value in this sequence at the specified index. The first 

charvalue is at index 

0, the next at index 

1, and so on, as in array indexing.

The index argument must be greater than or equal to 0, and less than the length of this sequence.

If the char value specified by the index is a , the surrogate value is returned.

Specified by:

 in interface 

Parameters:

index - the index of the desired 

char value.

Returns:

the 

char value at the specified index.

Throws:

 - if 

index is negative or greater than or equal to

length().

See Also:

---

codePointAt

public int codePointAt(int index)

Returns the character (Unicode code point) at the specified index. The index refers to 

char values (Unicode code units) and ranges from 

0 to   

- 1.

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

Parameters:

index - the index to the 

char values

Returns:

the code point value of the character at the 

index

Since:

1.5

---

codePointBefore

public int codePointBefore(int index)

Returns the character (Unicode code point) before the specified index. The index refers to 

char values (Unicode code units) and ranges from 

1 to  .

If the char value at (index - 1) is in the low-surrogate range, (index - 2) is not negative, and the char value at (index - 2) is in the high-surrogate range, then the supplementary code point value of the surrogate pair is returned. If the charvalue at index - 1 is 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.

Since:

1.5

---

codePointCount

public int codePointCount(int beginIndex, int endIndex)

Returns the number of Unicode code points in the specified text range of this sequence. The text range begins at the specified 

beginIndex and extends to the 

charat index 

endIndex - 1. Thus the length (in 

chars) of the text range is 

endIndex-beginIndex. Unpaired surrogates within this sequence count as one code point each.

Parameters:

beginIndex - the index to the first 

char of the text range.

endIndex - the index after the last 

char of the text range.

Returns:

the number of Unicode code points in the specified text range

Since:

1.5

---

offsetByCodePoints

public int offsetByCodePoints(int index, int codePointOffset)

Returns the index within this sequence that is offset from the given 

index by

codePointOffset code points. Unpaired surrogates within the text range given by

index and 

codePointOffset count as one code point each.

Parameters:

index - the index to be offset

codePointOffset - the offset in code points

Returns:

the index within this sequence

Since:

1.5

---

getChars

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

Characters are copied from this sequence into the destination character array 

dst. 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 are copied into the subarray of 

dst starting at index

dstBegin and ending at index:

dstbegin + (srcEnd-srcBegin) - 1

Parameters:

srcBegin - start copying at this offset.

srcEnd - stop copying at this offset.

dst - the array to copy the data into.

dstBegin - offset into 

dst.

Throws:

 - if 

dst is 

null.

 - if any of the following is true:

• srcBegin is negative
• dstBegin is negative
• the srcBegin argument is greater than the srcEnd argument.
• srcEnd is greater than this.length().
• dstBegin+srcEnd-srcBegin is greater than dst.length

---

setCharAt

public void setCharAt(int index, char ch)

The character at the specified index is set to 

ch. This sequence is altered to represent a new character sequence that is identical to the old character sequence, except that it contains the character 

ch at position 

index.

The index argument must be greater than or equal to 0, and less than the length of this sequence.

Parameters:

index - the index of the character to modify.

ch - the new character.

Throws:

 - if 

index is negative or greater than or equal to

length().

See Also:

---

append

public  append( obj)

Appends the string representation of the 

Object argument.

The argument is converted to a string as if by the method String.valueOf, and the characters of that string are then appended to this sequence.

Parameters:

obj - an 

Object.

Returns:

a reference to this object.

See Also:

, 

---

append

public  append( str)

Appends the specified string to this character sequence.

The characters of the String argument are appended, in order, increasing the length of this sequence by the length of the argument. If str is null, then the four characters "null" are appended.

Let n be the length of this character sequence just prior to execution of theappend method. Then the character at index k in the new character sequence is equal to the character at index k in the old character sequence, if k is less than n; otherwise, it is equal to the character at index k-n in the argument str.

Parameters:

str - a string.

Returns:

a reference to this object.

---

append

public  append( sb)

Appends the specified 

StringBuffer to this sequence.

The characters of the StringBuffer argument are appended, in order, to the contents of this StringBuffer, increasing the length of this StringBuffer by the length of the argument. If sb is null, then the four characters "null" are appended to thisStringBuffer.

Let n be the length of the old character sequence, the one contained in theStringBuffer just prior to execution of the append method. Then the character at index k in the new character sequence is equal to the character at index k in the old character sequence, if k is less than n; otherwise, it is equal to the character at index k-n in the argument sb.

This method synchronizes on this (the destination) object but does not synchronize on the source (sb).

Parameters:

sb - the 

StringBuffer to append.

Returns:

a reference to this object.

Since:

1.4

---

append

public  append( s)

Appends the specified 

CharSequence to this sequence.

The characters of the CharSequence argument are appended, in order, increasing the length of this sequence by the length of the argument.

The result of this method is exactly the same as if it were an invocation of this.append(s, 0, s.length());

This method synchronizes on this (the destination) object but does not synchronize on the source (s).

If s is null, then the four characters "null" are appended.

Specified by:

 in interface 

Parameters:

s - the 

CharSequence to append.

Returns:

a reference to this object.

Since:

1.5

---

append

public  append( s, int start, int end)

Appends a subsequence of the specified 

CharSequence to this sequence.

Characters of the argument s, starting at index start, are appended, in order, to the contents of this sequence up to the (exclusive) index end. The length of this sequence is increased by the value of end - start.

Let n be the length of this character sequence just prior to execution of theappend method. Then the character at index k in this character sequence becomes equal to the character at index k in this sequence, if k is less than n; otherwise, it is equal to the character at index k+start-n in the argument s.

If s is null, then this method appends characters as if the s parameter was a sequence containing the four characters "null".

Specified by:

 in interface 

Parameters:

s - the sequence to append.

start - the starting index of the subsequence to be appended.

end - the end index of the subsequence to be appended.

Returns:

a reference to this object.

Throws:

 - if 

start or 

end are negative, or 

start is greater than 

end or 

end is greater than 

s.length()

Since:

1.5

---

append

public  append(char[] str)

Appends the string representation of the 

char array argument to this sequence.

The characters of the array argument are appended, in order, to the contents of this sequence. The length of this sequence increases by the length of the argument.

The overall effect is exactly as if the argument were converted to a string by the method  and the characters of that string were then to this character sequence.

Parameters:

str - the characters to be appended.

Returns:

a reference to this object.

---

append

public  append(char[] str, int offset, int len)

Appends the string representation of a subarray of the 

char array argument to this sequence.

Characters of the char array str, starting at index offset, are appended, in order, to the contents of this sequence. The length of this sequence increases by the value of len.

The overall effect is exactly as if the arguments were converted to a string by the method  and the characters of that string were then to this character sequence.

Parameters:

str - the characters to be appended.

offset - the index of the first 

char to append.

len - the number of 

chars to append.

Returns:

a reference to this object.

---

append

public  append(boolean b)

Appends the string representation of the 

boolean argument to the sequence.

The argument is converted to a string as if by the method String.valueOf, and the characters of that string are then appended to this sequence.

Parameters:

b - a 

boolean.

Returns:

a reference to this object.

See Also:

, 

---

append

public  append(char c)

Appends the string representation of the 

char argument to this sequence.

The argument is appended to the contents of this sequence. The length of this sequence increases by 1.

The overall effect is exactly as if the argument were converted to a string by the method  and the character in that string were then  to this character sequence.

Specified by:

 in interface 

Parameters:

c - a 

char.

Returns:

a reference to this object.

---

append

public  append(int i)

Appends the string representation of the 

int argument to this sequence.

The argument is converted to a string as if by the method String.valueOf, and the characters of that string are then appended to this sequence.

Parameters:

i - an 

int.

Returns:

a reference to this object.

See Also:

, 

---

appendCodePoint

public  appendCodePoint(int codePoint)

Appends the string representation of the 

codePoint argument to this sequence.

The argument is appended to the contents of this sequence. The length of this sequence increases by .

The overall effect is exactly as if the argument were converted to a char array by the method  and the character in that array were then to this character sequence.

Parameters:

codePoint - a Unicode code point

Returns:

a reference to this object.

Since:

1.5

---

append

public  append(long lng)

Appends the string representation of the 

long argument to this sequence.

The argument is converted to a string as if by the method String.valueOf, and the characters of that string are then appended to this sequence.

Parameters:

lng - a 

long.

Returns:

a reference to this object.

See Also:

, 

---

append

public  append(float f)

Appends the string representation of the 

float argument to this sequence.

The argument is converted to a string as if by the method String.valueOf, and the characters of that string are then appended to this string sequence.

Parameters:

f - a 

float.

Returns:

a reference to this object.

See Also:

, 

---

append

public  append(double d)

Appends the string representation of the 

double argument to this sequence.

The argument is converted to a string as if by the method String.valueOf, and the characters of that string are then appended to this sequence.

Parameters:

d - a 

double.

Returns:

a reference to this object.

See Also:

, 

---

delete

public  delete(int start, int end)

Removes the characters in a substring of this sequence. The substring begins at the specified 

start and extends to the character at index 

end - 1 or to the end of the sequence if no such character exists. If 

start is equal to 

end, no changes are made.

Parameters:

start - The beginning index, inclusive.

end - The ending index, exclusive.

Returns:

This object.

Throws:

 - if 

start is negative, greater than 

length(), or greater than 

end.

Since:

1.2

---

deleteCharAt

public  deleteCharAt(int index)

Removes the 

char at the specified position in this sequence. This sequence is shortened by one 

char.

Note: If the character at the given index is a supplementary character, this method does not remove the entire character. If correct handling of supplementary characters is required, determine the number of chars to remove by callingCharacter.charCount(thisSequence.codePointAt(index)), where thisSequence is this sequence.

Parameters:

index - Index of 

char to remove

Returns:

This object.

Throws:

 - if the 

index is negative or greater than or equal to 

length().

Since:

1.2

---

replace

public  replace(int start, int end,  str)

Replaces the characters in a substring of this sequence with characters in the specified 

String. The substring begins at the specified 

start and extends to the character at index 

end - 1 or to the end of the sequence if no such character exists. First the characters in the substring are removed and then the specified

String is inserted at 

start. (This sequence will be lengthened to accommodate the specified String if necessary.)

Parameters:

start - The beginning index, inclusive.

end - The ending index, exclusive.

str - String that will replace previous contents.

Returns:

This object.

Throws:

 - if 

start is negative, greater than 

length(), or greater than 

end.

Since:

1.2

---

substring

public  substring(int start)

Returns a new 

String that contains a subsequence of characters currently contained in this character sequence. The substring begins at the specified index and extends to the end of this sequence.

Parameters:

start - The beginning index, inclusive.

Returns:

The new string.

Throws:

 - if 

start is less than zero, or greater than the length of this object.

Since:

1.2

---

subSequence

public  subSequence(int start, int end)

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

An invocation of this method of the form

sb.subSequence(begin, end)

behaves in exactly the same way as the invocation

sb.substring(begin, end)

This method is provided so that this class can implement the  interface.

Specified by:

 in interface 

Parameters:

start - the start index, inclusive.

end - the end index, exclusive.

Returns:

the specified subsequence.

Throws:

 - if 

start or 

end are negative, if 

end is greater than 

length(), or if 

start is greater than 

end

Since:

1.4

---

substring

public  substring(int start, int end)

Returns a new 

String that contains a subsequence of characters currently contained in this sequence. The substring begins at the specified 

start and extends to the character at index 

end - 1.

Parameters:

start - The beginning index, inclusive.

end - The ending index, exclusive.

Returns:

The new string.

Throws:

 - if 

start or 

end are negative or greater than

length(), or 

start is greater than 

end.

Since:

1.2

---

insert

public  insert(int index, char[] str, int offset, int len)

Inserts the string representation of a subarray of the 

str array argument into this sequence. The subarray begins at the specified 

offset and extends 

len 

chars. The characters of the subarray are inserted into this sequence at the position indicated by 

index. The length of this sequence increases by 

len 

chars.

Parameters:

index - position at which to insert subarray.

str - A 

char array.

offset - the index of the first 

char in subarray to be inserted.

len - the number of 

chars in the subarray to be inserted.

Returns:

This object

Throws:

 - if 

index is negative or greater than

length(), or 

offset or 

len are negative, or 

(offset+len) is greater than

str.length.

Since:

1.2

---

insert

public  insert(int offset,  obj)

Inserts the string representation of the 

Object argument into this character sequence.

The second argument is converted to a string as if by the method String.valueOf, and the characters of that string are then inserted into this sequence at the indicated offset.

The offset argument must be greater than or equal to 0, and less than or equal to the length of this sequence.

Parameters:

offset - the offset.

obj - an 

Object.

Returns:

a reference to this object.

Throws:

 - if the offset is invalid.

See Also:

,  , 

---

insert

public  insert(int offset,  str)

Inserts the string into this character sequence.

The characters of the String argument are inserted, in order, into this sequence at the indicated offset, moving up any characters originally above that position and increasing the length of this sequence by the length of the argument. If str isnull, then the four characters "null" are inserted into this sequence.

The character at index k in the new character sequence is equal to:

• the character at index k in the old character sequence, if k is less thanoffset
• the character at index k-offset in the argument str, if k is not less thanoffset but is less than offset+str.length()
• the character at index k-str.length() in the old character sequence, if k is not less than offset+str.length()

The offset argument must be greater than or equal to 0, and less than or equal to the length of this sequence.

Parameters:

offset - the offset.

str - a string.

Returns:

a reference to this object.

Throws:

 - if the offset is invalid.

See Also:

---

insert

public  insert(int offset, char[] str)

Inserts the string representation of the 

char array argument into this sequence.

The characters of the array argument are inserted into the contents of this sequence at the position indicated by offset. The length of this sequence increases by the length of the argument.

The overall effect is exactly as if the argument were converted to a string by the method  and the characters of that string were then into this character sequence at the position indicated by offset.

Parameters:

offset - the offset.

str - a character array.

Returns:

a reference to this object.

Throws:

 - if the offset is invalid.

---

insert

public  insert(int dstOffset,  s)

Inserts the specified 

CharSequence into this sequence.

The characters of the CharSequence argument are inserted, in order, into this sequence at the indicated offset, moving up any characters originally above that position and increasing the length of this sequence by the length of the argument s.

The result of this method is exactly the same as if it were an invocation of this object's insert(dstOffset, s, 0, s.length()) method.

If s is null, then the four characters "null" are inserted into this sequence.

Parameters:

dstOffset - the offset.

s - the sequence to be inserted

Returns:

a reference to this object.

Throws:

 - if the offset is invalid.

Since:

1.5

---

insert

public  insert(int dstOffset,  s, int start, int end)

Inserts a subsequence of the specified 

CharSequence into this sequence.

The subsequence of the argument s specified by start and end are inserted, in order, into this sequence at the specified destination offset, moving up any characters originally above that position. The length of this sequence is increased by end - start.

The character at index k in this sequence becomes equal to:

• the character at index k in this sequence, if k is less than dstOffset
• the character at index k+start-dstOffset in the argument s, if k is greater than or equal to dstOffset but is less than dstOffset+end-start
• the character at index k-(end-start) in this sequence, if k is greater than or equal to dstOffset+end-start

The dstOffset argument must be greater than or equal to 0, and less than or equal to the length of this sequence.

The start argument must be nonnegative, and not greater than end.

The end argument must be greater than or equal to start, and less than or equal to the length of s.

If s is null, then this method inserts characters as if the s parameter was a sequence containing the four characters "null".

Parameters:

dstOffset - the offset in this sequence.

s - the sequence to be inserted.

start - the starting index of the subsequence to be inserted.

end - the end index of the subsequence to be inserted.

Returns:

a reference to this object.

Throws:

 - if 

dstOffset is negative or greater than

this.length(), or 

start or 

end are negative, or 

start is greater than 

end or

end is greater than 

s.length()

Since:

1.5

---

insert

public  insert(int offset, boolean b)

Inserts the string representation of the 

boolean argument into this sequence.

The second argument is converted to a string as if by the method String.valueOf, and the characters of that string are then inserted into this sequence at the indicated offset.

The offset argument must be greater than or equal to 0, and less than or equal to the length of this sequence.

Parameters:

offset - the offset.

b - a 

boolean.

Returns:

a reference to this object.

Throws:

 - if the offset is invalid.

See Also:

,  , 

---

insert

public  insert(int offset, char c)

Inserts the string representation of the 

char argument into this sequence.

The second argument is inserted into the contents of this sequence at the position indicated by offset. The length of this sequence increases by one.

The overall effect is exactly as if the argument were converted to a string by the method  and the character in that string were then into this character sequence at the position indicated by offset.

The offset argument must be greater than or equal to 0, and less than or equal to the length of this sequence.

Parameters:

offset - the offset.

c - a 

char.

Returns:

a reference to this object.

Throws:

 - if the offset is invalid.

See Also:

---

insert

public  insert(int offset, int i)

Inserts the string representation of the second 

int argument into this sequence.

The second argument is converted to a string as if by the method String.valueOf, and the characters of that string are then inserted into this sequence at the indicated offset.

The offset argument must be greater than or equal to 0, and less than or equal to the length of this sequence.

Parameters:

offset - the offset.

i - an 

int.

Returns:

a reference to this object.

Throws:

 - if the offset is invalid.

See Also:

,  , 

---

insert

public  insert(int offset, long l)

Inserts the string representation of the 

long argument into this sequence.

The second argument is converted to a string as if by the method String.valueOf, and the characters of that string are then inserted into this sequence at the position indicated by offset.

The offset argument must be greater than or equal to 0, and less than or equal to the length of this sequence.

Parameters:

offset - the offset.

l - a 

long.

Returns:

a reference to this object.

Throws:

 - if the offset is invalid.

See Also:

,  , 

---

insert

public  insert(int offset, float f)

Inserts the string representation of the 

float argument into this sequence.

The second argument is converted to a string as if by the method String.valueOf, and the characters of that string are then inserted into this sequence at the indicated offset.

The offset argument must be greater than or equal to 0, and less than or equal to the length of this sequence.

Parameters:

offset - the offset.

f - a 

float.

Returns:

a reference to this object.

Throws:

 - if the offset is invalid.

See Also:

,  , 

---

insert

public  insert(int offset, double d)

Inserts the string representation of the 

double argument into this sequence.

The second argument is converted to a string as if by the method String.valueOf, and the characters of that string are then inserted into this sequence at the indicated offset.

The offset argument must be greater than or equal to 0, and less than or equal to the length of this sequence.

Parameters:

offset - the offset.

d - a 

double.

Returns:

a reference to this object.

Throws:

 - if the offset is invalid.

See Also:

,  , 

---

indexOf

public int indexOf( str)

Returns the index within this string of the first occurrence of the specified substring. The integer returned is the smallest value 

k such that:

this.toString().startsWith(str, k)

is 

true.

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.

Throws:

 - if 

str is 

null.

Since:

1.4

---

indexOf

public int indexOf( str, int fromIndex)

Returns the index within this string of the first occurrence of the specified substring, starting at the specified index. The integer returned is the smallest value 

k for which:

k >= Math.min(fromIndex, str.length()) && this.toString().startsWith(str, k)

If no such value of 

k exists, then -1 is returned.

Parameters:

str - the substring for which to search.

fromIndex - the index from which to start the search.

Returns:

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

Throws:

 - if 

str is 

null.

Since:

1.4

---

lastIndexOf

public int lastIndexOf( str)

Returns the index within this string of the rightmost occurrence of the specified substring. The rightmost empty string "" is considered to occur at the index value

this.length(). The returned index is the largest value 

k such that

this.toString().startsWith(str, k)

is true.

Parameters:

str - the substring to search for.

Returns:

if the string argument occurs one or more times 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.

Throws:

 - if 

str is 

null.

Since:

1.4

---

lastIndexOf

public int lastIndexOf( str, int fromIndex)

Returns the index within this string of the last occurrence of the specified substring. The integer returned is the largest value 

k such that:

k <= Math.min(fromIndex,="Math.min(fromIndex," str.length())="str.length())" &&="&&" this.toString().startsWith(str,="this.toString().startsWith(str," k)="k)"

If no such value of 

k exists, then -1 is returned.

Parameters:

str - the substring to search for.

fromIndex - the index to start the search from.

Returns:

the index within this sequence of the last occurrence of the specified substring.

Throws:

 - if 

str is 

null.

Since:

1.4

---

reverse

public  reverse()

Causes this character sequence to be replaced by the reverse of the sequence. If there are any surrogate pairs included in the sequence, these are treated as single characters for the reverse operation. Thus, the order of the high-low surrogates is never reversed. Let 

n be the character length of this character sequence (not the length in 

char values) just prior to execution of the 

reverse method. Then the character at index 

k in the new character sequence is equal to the character at index 

n-k-1 in the old character sequence.

Note that the reverse operation may result in producing surrogate pairs that were unpaired low-surrogates and high-surrogates before the operation. For example, reversing "\uDC00\uD800" produces "\uD800\uDC00" which is a valid surrogate pair.

Returns:

a reference to this object.

Since:

JDK1.0.2

---

toString

public  toString()

Returns a string representing the data in this sequence. A new 

String object is allocated and initialized to contain the character sequence currently represented by this object. This 

String is then returned. Subsequent changes to this sequence do not affect the contents of the 

String.

Specified by:

 in interface 

Returns:

a string representation of this sequence of characters.

---

Class

Java™ Platform
Standard Ed. 6

SUMMARY: NESTED | FIELD |  | 

DETAIL: FIELD |  | 

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For further API reference and developer documentation, see . That documentation contains more detailed, developer-targeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.

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