length( ) and capacity( )
The current length of a StringBuffer can be found via the length( ) method, while the total
allocated capacity can be found through the capacity( ) method. They have the following
general forms:
int length( )
int capacity( )
Here is an example:
// StringBuffer length vs. capacity.
class StringBufferDemo {
public static void main(String args[]) {
StringBuffer sb = new StringBuffer("Hello");
System.out.println("buffer = " + sb);
System.out.println("length = " + sb.length());
System.out.println("capacity = " + sb.capacity());
}
}
Here is the output of this program, which shows how StringBuffer reserves extra space
for additional manipulations:
buffer = Hello
length = 5
capacity = 21
Since sb is initialized with the string "Hello" when it is created, its length is 5. Its capacity is 21
because room for 16 additional characters is automatically added.
ensureCapacity( )
If you want to preallocate room for a certain number of characters after a StringBuffer has
been constructed, you can use ensureCapacity( ) to set the size of the buffer. This is useful
if you know in advance that you will be appending a large number of small strings to a
StringBuffer. ensureCapacity( ) has this general form:
void ensureCapacity(int capacity)
Here, capacity specifies the size of the buffer.
setLength( )
To set the length of the buffer within a StringBuffer object, use setLength( ). Its general form
is shown here:
void setLength(int len)
Here, len specifies the length of the buffer. This value must be nonnegative.
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