20.13

java.lang.StringBuffer

THE PACKAGE JAVA.LANG

20.13.1

public StringBuffer()

This constructor initializes a newly created

StringBuffer

 object so that it ini 

tially represents an empty character sequence and has capacity 16.

20.13.2

public StringBuffer(int length)

throws NegativeArraySizeException

This constructor initializes a newly created

StringBuffer

 object so that it ini 

tially represents an empty character sequence, but has the capacity specified by

the argument.

If the argument is negative, a

NegativeArraySizeException

 is thrown.

20.13.3

public StringBuffer(String str)

This constructor initializes a newly created

StringBuffer

 object so that it repre 

sents the same sequence of characters as the argument; in other words, the initial

contents of the string buffer is a copy of the argument string. The initial capacity

of the string buffer is 16 plus the length of the argument string.

20.13.4

public String toString()

A new

String

 object is created and initialized to contain the character sequence

currently represented by the string buffer; the new

String

 is then returned. Any

subsequent changes to the string buffer do not affect the contents of the returned

string.

Implementation advice: This method can be coded so as to create a new

String

 object without allocating new memory to hold a copy of the character

sequence. Instead, the string can share the memory used by the string buffer. Any

subsequent operation that alters the content or capacity of the string buffer must

then make a copy of the internal buffer at that time. This strategy is effective for

reducing the amount of memory allocated by a string concatenation operation

( 15.17.1) when it is implemented using a string buffer.

Overrides the

toString

 method of

Object

 ( 20.1.2).

20.13.5

public int length()

This method returns the length of the sequence of characters currently represented

by this

StringBuffer

 object.

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