StringBuffer (Java Platform SE 8 ) (original) (raw)

public int length()
Returns the length (character count).
Specified by:
[length](../../java/lang/CharSequence.html#length--) in interface [CharSequence](../../java/lang/CharSequence.html "interface in java.lang")
Returns:
the length of the sequence of characters currently represented by this object

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

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:

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 capacity() method.
Since:
1.5

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 the newLength argument.
The newLength argument must be greater than or equal to 0.
Parameters:
newLength - the new length
Throws:
[IndexOutOfBoundsException](../../java/lang/IndexOutOfBoundsException.html "class in java.lang") - if thenewLength argument is negative.
See Also:
length()

public char charAt(int index)
Returns the char value in this sequence at the specified index. The first char value is at index 0, the next at index1, and so on, as in array indexing.
The index argument must be greater than or equal to0, and less than the length of this sequence.
If the char value specified by the index is asurrogate, the surrogate value is returned.
Specified by:
[charAt](../../java/lang/CharSequence.html#charAt-int-) in interface [CharSequence](../../java/lang/CharSequence.html "interface in java.lang")
Parameters:
index - the index of the desired char value.
Returns:
the char value at the specified index.
Throws:
[IndexOutOfBoundsException](../../java/lang/IndexOutOfBoundsException.html "class in java.lang") - if index is negative or greater than or equal to length().
See Also:
length()

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 tolength()- 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 thechar 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 theindex
Since:
1.5

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 length().
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 char value 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

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 specifiedbeginIndex and extends to the char at index endIndex - 1. Thus the length (inchars) of the text range isendIndex-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

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 byindex 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

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:
[IndexOutOfBoundsException](../../java/lang/IndexOutOfBoundsException.html "class in java.lang") - if any of the following is true:

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 to0, and less than the length of this sequence.
Parameters:
index - the index of the character to modify.
ch - the new character.
Throws:
[IndexOutOfBoundsException](../../java/lang/IndexOutOfBoundsException.html "class in java.lang") - if index is negative or greater than or equal to length().
See Also:
length()

public StringBuffer append(Object obj)
Appends the string representation of the Object argument.
The overall effect is exactly as if the argument were converted to a string by the method String.valueOf(Object), and the characters of that string were thenappended to this character sequence.
Parameters:
obj - an Object.
Returns:
a reference to this object.

public StringBuffer append(String 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 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 str.
Parameters:
str - a string.
Returns:
a reference to this object.

public StringBuffer append(StringBuffer 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 this StringBuffer.
Let n be the length of the old character sequence, the one contained in the StringBuffer 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 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

public StringBuffer append(CharSequence 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:
[append](../../java/lang/Appendable.html#append-java.lang.CharSequence-) in interface [Appendable](../../java/lang/Appendable.html "interface in java.lang")
Parameters:
s - the CharSequence to append.
Returns:
a reference to this object.
Since:
1.5

public StringBuffer append(CharSequence 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 the append 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:
[append](../../java/lang/Appendable.html#append-java.lang.CharSequence-int-int-) in interface [Appendable](../../java/lang/Appendable.html "interface in java.lang")
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:
[IndexOutOfBoundsException](../../java/lang/IndexOutOfBoundsException.html "class in java.lang") - ifstart is negative, orstart is greater than end orend is greater than s.length()
Since:
1.5

public StringBuffer 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 String.valueOf(char[]), and the characters of that string were thenappended to this character sequence.
Parameters:
str - the characters to be appended.
Returns:
a reference to this object.

public StringBuffer append(char[] str,
int offset,
int len)
Appends the string representation of a subarray of thechar 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 String.valueOf(char[],int,int), and the characters of that string were thenappended 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.
Throws:
[IndexOutOfBoundsException](../../java/lang/IndexOutOfBoundsException.html "class in java.lang") - if offset < 0 or len < 0 or offset+len > str.length

public StringBuffer append(boolean b)
Appends the string representation of the boolean argument to the sequence.
The overall effect is exactly as if the argument were converted to a string by the method String.valueOf(boolean), and the characters of that string were thenappended to this character sequence.
Parameters:
b - a boolean.
Returns:
a reference to this object.

public StringBuffer 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 String.valueOf(char), and the character in that string were thenappended to this character sequence.
Specified by:
[append](../../java/lang/Appendable.html#append-char-) in interface [Appendable](../../java/lang/Appendable.html "interface in java.lang")
Parameters:
c - a char.
Returns:
a reference to this object.

public StringBuffer append(int i)
Appends the string representation of the int argument to this sequence.
The overall effect is exactly as if the argument were converted to a string by the method String.valueOf(int), and the characters of that string were thenappended to this character sequence.
Parameters:
i - an int.
Returns:
a reference to this object.

public StringBuffer 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 byCharacter.charCount(codePoint).
The overall effect is exactly as if the argument were converted to a char array by the methodCharacter.toChars(int) and the character in that array were then appended to this character sequence.
Parameters:
codePoint - a Unicode code point
Returns:
a reference to this object.
Since:
1.5

public StringBuffer append(long lng)
Appends the string representation of the long argument to this sequence.
The overall effect is exactly as if the argument were converted to a string by the method String.valueOf(long), and the characters of that string were thenappended to this character sequence.
Parameters:
lng - a long.
Returns:
a reference to this object.

public StringBuffer append(float f)
Appends the string representation of the float argument to this sequence.
The overall effect is exactly as if the argument were converted to a string by the method String.valueOf(float), and the characters of that string were thenappended to this character sequence.
Parameters:
f - a float.
Returns:
a reference to this object.

public StringBuffer append(double d)
Appends the string representation of the double argument to this sequence.
The overall effect is exactly as if the argument were converted to a string by the method String.valueOf(double), and the characters of that string were thenappended to this character sequence.
Parameters:
d - a double.
Returns:
a reference to this object.

public StringBuffer 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. Ifstart is equal to end, no changes are made.
Parameters:
start - The beginning index, inclusive.
end - The ending index, exclusive.
Returns:
This object.
Throws:
[StringIndexOutOfBoundsException](../../java/lang/StringIndexOutOfBoundsException.html "class in java.lang") - if start is negative, greater than length(), or greater than end.
Since:
1.2

public StringBuffer 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:
[StringIndexOutOfBoundsException](../../java/lang/StringIndexOutOfBoundsException.html "class in java.lang") - if the index is negative or greater than or equal tolength().
Since:
1.2

public StringBuffer replace(int start,
int end,
String 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 specifiedString 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:
[StringIndexOutOfBoundsException](../../java/lang/StringIndexOutOfBoundsException.html "class in java.lang") - if start is negative, greater than length(), or greater than end.
Since:
1.2

public String 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:
[StringIndexOutOfBoundsException](../../java/lang/StringIndexOutOfBoundsException.html "class in java.lang") - if start is less than zero, or greater than the length of this object.
Since:
1.2

public CharSequence 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,&nbsp;end)

behaves in exactly the same way as the invocation 

 sb.substring(begin,&nbsp;end)

This method is provided so that this class can implement the CharSequence interface.
Specified by:
[subSequence](../../java/lang/CharSequence.html#subSequence-int-int-) in interface [CharSequence](../../java/lang/CharSequence.html "interface in java.lang")
Parameters:
start - the start index, inclusive.
end - the end index, exclusive.
Returns:
the specified subsequence.
Throws:
[IndexOutOfBoundsException](../../java/lang/IndexOutOfBoundsException.html "class in java.lang") - if start or end are negative, if end is greater than length(), or if start is greater than end
Since:
1.4

public String 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:
[StringIndexOutOfBoundsException](../../java/lang/StringIndexOutOfBoundsException.html "class in java.lang") - if start or end are negative or greater thanlength(), or start is greater than end.
Since:
1.2

public StringBuffer 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:
[StringIndexOutOfBoundsException](../../java/lang/StringIndexOutOfBoundsException.html "class in java.lang") - if index is negative or greater than length(), oroffset or len are negative, or(offset+len) is greater thanstr.length.
Since:
1.2

public StringBuffer insert(int offset,
Object obj)
Inserts the string representation of the Object argument into this character sequence.
The overall effect is exactly as if the second argument were converted to a string by the method String.valueOf(Object), and the characters of that string were theninserted into this character sequence at the indicated offset.
The offset argument must be greater than or equal to0, 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:
[StringIndexOutOfBoundsException](../../java/lang/StringIndexOutOfBoundsException.html "class in java.lang") - if the offset is invalid.

public StringBuffer insert(int offset,
String 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. Ifstr is null, then the four characters"null" are inserted into this sequence.
The character at index k in the new character sequence is equal to:

public StringBuffer 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 byoffset. The length of this sequence increases by the length of the argument.
The overall effect is exactly as if the second argument were converted to a string by the method String.valueOf(char[]), and the characters of that string were theninserted into this character sequence at the indicated offset.
The offset argument must be greater than or equal to0, and less than or equal to the length of this sequence.
Parameters:
offset - the offset.
str - a character array.
Returns:
a reference to this object.
Throws:
[StringIndexOutOfBoundsException](../../java/lang/StringIndexOutOfBoundsException.html "class in java.lang") - if the offset is invalid.

public StringBuffer insert(int dstOffset,
CharSequence 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'sinsert(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:
[IndexOutOfBoundsException](../../java/lang/IndexOutOfBoundsException.html "class in java.lang") - if the offset is invalid.
Since:
1.5

public StringBuffer insert(int dstOffset,
CharSequence s,
int start,
int end)
Inserts a subsequence of the specified CharSequence into this sequence.
The subsequence of the argument s specified bystart 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:

public StringBuffer insert(int offset,
boolean b)
Inserts the string representation of the boolean argument into this sequence.
The overall effect is exactly as if the second argument were converted to a string by the method String.valueOf(boolean), and the characters of that string were theninserted into this character sequence at the indicated offset.
The offset argument must be greater than or equal to0, 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:
[StringIndexOutOfBoundsException](../../java/lang/StringIndexOutOfBoundsException.html "class in java.lang") - if the offset is invalid.

public StringBuffer insert(int offset,
char c)
Inserts the string representation of the char argument into this sequence.
The overall effect is exactly as if the second argument were converted to a string by the method String.valueOf(char), and the character in that string were theninserted into this character sequence at the indicated offset.
The offset argument must be greater than or equal to0, 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:
[IndexOutOfBoundsException](../../java/lang/IndexOutOfBoundsException.html "class in java.lang") - if the offset is invalid.

public StringBuffer insert(int offset,
int i)
Inserts the string representation of the second int argument into this sequence.
The overall effect is exactly as if the second argument were converted to a string by the method String.valueOf(int), and the characters of that string were theninserted into this character sequence at the indicated offset.
The offset argument must be greater than or equal to0, 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:
[StringIndexOutOfBoundsException](../../java/lang/StringIndexOutOfBoundsException.html "class in java.lang") - if the offset is invalid.

public StringBuffer insert(int offset,
long l)
Inserts the string representation of the long argument into this sequence.
The overall effect is exactly as if the second argument were converted to a string by the method String.valueOf(long), and the characters of that string were theninserted into this character sequence at the indicated offset.
The offset argument must be greater than or equal to0, 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:
[StringIndexOutOfBoundsException](../../java/lang/StringIndexOutOfBoundsException.html "class in java.lang") - if the offset is invalid.

public StringBuffer insert(int offset,
float f)
Inserts the string representation of the float argument into this sequence.
The overall effect is exactly as if the second argument were converted to a string by the method String.valueOf(float), and the characters of that string were theninserted into this character sequence at the indicated offset.
The offset argument must be greater than or equal to0, 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:
[StringIndexOutOfBoundsException](../../java/lang/StringIndexOutOfBoundsException.html "class in java.lang") - if the offset is invalid.

public StringBuffer insert(int offset,
double d)
Inserts the string representation of the double argument into this sequence.
The overall effect is exactly as if the second argument were converted to a string by the method String.valueOf(double), and the characters of that string were theninserted into this character sequence at the indicated offset.
The offset argument must be greater than or equal to0, 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:
[StringIndexOutOfBoundsException](../../java/lang/StringIndexOutOfBoundsException.html "class in java.lang") - if the offset is invalid.

public int indexOf(String 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, <i>k</i>)

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.
Since:
1.4

public int indexOf(String 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, this.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.
Since:
1.4

public int lastIndexOf(String 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.
Since:
1.4

public int lastIndexOf(String 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, this.length()) &&  
                   this.toString().startsWith(str, 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.
Since:
1.4

public StringBuffer 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

public String 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 theString.
Specified by:
[toString](../../java/lang/CharSequence.html#toString--) in interface [CharSequence](../../java/lang/CharSequence.html "interface in java.lang")
Returns:
a string representation of this sequence of characters.