Class java.lang.StringBuffer 
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Class java.lang.StringBuffer 

java.lang.Object
|
   +----java.lang.StringBuffer
public final class StringBuffer
extends Object
This Class is a growable buffer for characters. It is mainly used to create Strings. The compiler uses it to implement the "+" operator. For example: 
"a" + 4 + "c"
is compiled to: 
new StringBuffer().append("a").append(4).append("c").toString()
Note that the method toString() does not create a copy of the internal buffer. Instead the buffer is marked as shared. Any further changes to the buffer will cause a copy to be made.

See Also:
String, ByteArrayOutputStream

Constructor Index

o StringBuffer()
Constructs an empty String buffer.
o StringBuffer(int)
Constructs an empty String buffer with the specified initial length.
o StringBuffer(String)
Constructs a String buffer with the specified initial value.

Method Index

o append(boolean)
Appends a boolean to the end of this buffer.
o append(char)
Appends a character to the end of this buffer.
o append(char[])
Appends an array of characters to the end of this buffer.
o append(char[], int, int)
Appends a part of an array of characters to the end of this buffer.
o append(double)
Appends a double to the end of this buffer.
o append(float)
Appends a float to the end of this buffer.
o append(int)
Appends an integer to the end of this buffer.
o append(long)
Appends a long to the end of this buffer.
o append(Object)
Appends an object to the end of this buffer.
o append(String)
Appends a String to the end of this buffer.
o capacity()
Returns the current capacity of the String buffer.
o charAt(int)
Returns the character at the specified index.
o ensureCapacity(int)
Ensures that the capacity of the buffer is at least equal to the specified minimum.
o getChars(int, int, char[], int)
Copies the characters of the specified substring (determined by srcBegin and srcEnd) into the character array, starting at the array's dstBegin location.
o insert(int, boolean)
Inserts a boolean into the String buffer.
o insert(int, char)
Inserts a character into the String buffer.
o insert(int, char[])
Inserts an array of characters into the String buffer.
o insert(int, double)
Inserts a double into the String buffer.
o insert(int, float)
Inserts a float into the String buffer.
o insert(int, int)
Inserts an integer into the String buffer.
o insert(int, long)
Inserts a long into the String buffer.
o insert(int, Object)
Inserts an object into the String buffer.
o insert(int, String)
Inserts a String into the String buffer.
o length()
Returns the length (character count) of the buffer.
o reverse()
Reverse the order of the characters in the String buffer.
o setCharAt(int, char)
Changes the character at the specified index to be ch.
o setLength(int)
Sets the length of the String.
o toString()
Converts to a String representing the data in the buffer.

Constructors

o StringBuffer 
public StringBuffer()
Constructs an empty String buffer.
o StringBuffer 
public StringBuffer(int length)
Constructs an empty String buffer with the specified initial length.
Parameters:
length - the initial length
o StringBuffer 
public StringBuffer(String str)
Constructs a String buffer with the specified initial value.
Parameters:
str - the initial value of the buffer

Methods

o length 
public int length()
Returns the length (character count) of the buffer.
o capacity 
public int capacity()
Returns the current capacity of the String buffer. The capacity is the amount of storage available for newly inserted characters; beyond which an allocation will occur.
o ensureCapacity 
public synchronized void ensureCapacity(int minimumCapacity)
Ensures that the capacity of the buffer is at least equal to the specified minimum.
Parameters:
minimumCapacity - the minimum desired capacity
o setLength 
public synchronized void setLength(int newLength)
Sets the length of the String. If the length is reduced, characters are lost. If the length is extended, the values of the new characters are set to 0.
Parameters:
newLength - the new length of the buffer
Throws: StringIndexOutOfBoundsException
If the length is invalid.
o charAt 
public synchronized char charAt(int index)
Returns the character at the specified index. An index ranges from 0..length()-1.
Parameters:
index - the index of the desired character
Throws: StringIndexOutOfBoundsException
If the index is invalid.
o getChars 
public synchronized void getChars(int srcBegin,
                                    int srcEnd,
                                    char dst[],
                                    int dstBegin)
Copies the characters of the specified substring (determined by srcBegin and srcEnd) into the character array, starting at the array's dstBegin location. Both srcBegin and srcEnd must be legal indexes into the buffer.
Parameters:
srcBegin - begin copy at this offset in the String
srcEnd - stop copying at this offset in the String
dst - the array to copy the data into
dstBegin - offset into dst
Throws: StringIndexOutOfBoundsException
If there is an invalid index into the buffer.
o setCharAt 
public synchronized void setCharAt(int index,
                                     char ch)
Changes the character at the specified index to be ch.
Parameters:
index - the index of the character
ch - the new character
Throws: StringIndexOutOfBoundsException
If the index is invalid.
o append 
public synchronized StringBuffer append(Object obj)
Appends an object to the end of this buffer.
Parameters:
obj - the object to be appended
Returns:
the StringBuffer itself, NOT a new one.
o append 
public synchronized StringBuffer append(String str)
Appends a String to the end of this buffer.
Parameters:
str - the String to be appended
Returns:
the StringBuffer itself, NOT a new one.
o append 
public synchronized StringBuffer append(char str[])
Appends an array of characters to the end of this buffer.
Parameters:
str - the characters to be appended
Returns:
the StringBuffer itself, NOT a new one.
o append 
public synchronized StringBuffer append(char str[],
                                          int offset,
                                          int len)
Appends a part of an array of characters to the end of this buffer.
Parameters:
str - the characters to be appended
offset - where to start
len - the number of characters to add
Returns:
the StringBuffer itself, NOT a new one.
o append 
public StringBuffer append(boolean b)
Appends a boolean to the end of this buffer.
Parameters:
b - the boolean to be appended
Returns:
the StringBuffer itself, NOT a new one.
o append 
public synchronized StringBuffer append(char c)
Appends a character to the end of this buffer.
Parameters:
ch - the character to be appended
Returns:
the StringBuffer itself, NOT a new one.
o append 
public StringBuffer append(int i)
Appends an integer to the end of this buffer.
Parameters:
i - the integer to be appended
Returns:
the StringBuffer itself, NOT a new one.
o append 
public StringBuffer append(long l)
Appends a long to the end of this buffer.
Parameters:
l - the long to be appended
Returns:
the StringBuffer itself, NOT a new one.
o append 
public StringBuffer append(float f)
Appends a float to the end of this buffer.
Parameters:
f - the float to be appended
Returns:
the StringBuffer itself, NOT a new one.
o append 
public StringBuffer append(double d)
Appends a double to the end of this buffer.
Parameters:
d - the double to be appended
Returns:
the StringBuffer itself, NOT a new one.
o insert 
public synchronized StringBuffer insert(int offset,
Object obj)
Inserts an object into the String buffer.
Parameters:
offset - the offset at which to insert
obj - the object to insert
Returns:
the StringBuffer itself, NOT a new one.
Throws: StringIndexOutOfBoundsException
If the offset is invalid.
o insert 
public synchronized StringBuffer insert(int offset,
String str)
Inserts a String into the String buffer.
Parameters:
offset - the offset at which to insert
str - the String to insert
Returns:
the StringBuffer itself, NOT a new one.
Throws: StringIndexOutOfBoundsException
If the offset is invalid.
o insert 
public synchronized StringBuffer insert(int offset,
                                          char str[])
Inserts an array of characters into the String buffer.
Parameters:
offset - the offset at which to insert
str - the characters to insert
Returns:
the StringBuffer itself, NOT a new one.
Throws: StringIndexOutOfBoundsException
If the offset is invalid.
o insert 
public StringBuffer insert(int offset,
                             boolean b)
Inserts a boolean into the String buffer.
Parameters:
offset - the offset at which to insert
b - the boolean to insert
Returns:
the StringBuffer itself, NOT a new one.
Throws: StringIndexOutOfBoundsException
If the offset is invalid.
o insert 
public synchronized StringBuffer insert(int offset,
                                          char c)
Inserts a character into the String buffer.
Parameters:
offset - the offset at which to insert
ch - the character to insert
Returns:
the StringBuffer itself, NOT a new one.
Throws: StringIndexOutOfBoundsException
If the offset invalid.
o insert 
public StringBuffer insert(int offset,
                             int i)
Inserts an integer into the String buffer.
Parameters:
offset - the offset at which to insert
i - the integer to insert
Returns:
the StringBuffer itself, NOT a new one.
Throws: StringIndexOutOfBoundsException
If the offset is invalid.
o insert 
public StringBuffer insert(int offset,
                             long l)
Inserts a long into the String buffer.
Parameters:
offset - the offset at which to insert
l - the long to insert
Returns:
the StringBuffer itself, NOT a new one.
Throws: StringIndexOutOfBoundsException
If the offset is invalid.
o insert 
public StringBuffer insert(int offset,
                             float f)
Inserts a float into the String buffer.
Parameters:
offset - the offset at which to insert
f - the float to insert
Returns:
the StringBuffer itself, NOT a new one.
Throws: StringIndexOutOfBoundsException
If the offset is invalid.
o insert 
public StringBuffer insert(int offset,
                             double d)
Inserts a double into the String buffer.
Parameters:
offset - the offset at which to insert
d - the double to insert
Returns:
the StringBuffer itself, NOT a new one.
Throws: StringIndexOutOfBoundsException
If the offset is invalid.
o reverse 
public synchronized StringBuffer reverse()
Reverse the order of the characters in the String buffer.
o toString 
public String toString()
Converts to a String representing the data in the buffer.
Overrides:
toString in class Object 
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