Writing Files - Beginning Java - page 454

If you had allocated buf with 1023 bytes, then intBuf would have mapped to 1020 bytes of buf and would
have a capacity and limit of 255.
You could now use this view buffer to load the original buffer with values of type int . You could then
use the original byte buffer to write the int values to a file. As I said at the outset, view buffers have a sim-
ilar role when you are reading a file. You would have a primary buffer of type ByteBuffer into which you
read bytes from a file, and then you might access the contents of the ByteBuffer through a view buffer of
type DoubleBuffer to enable you to retrieve the data that is read from the file as values of type double .
The ByteBuffer class defines the methods for creating view buffers for a byte buffer object shown in
Table 10-6 .
TABLE 10-6 : Methods to Create View Buffers
METHOD DESCRIPTION
asCharBuffer() Returns a reference to a view buffer of type CharBuffer
asShortBuffer() Returns a reference to a view buffer of type ShortBuffer
asIntBuffer() Returns a reference to a view buffer of type IntBuffer
asLongBuffer() Returns a reference to a view buffer of type LongBuffer
asFloatBuffer() Returns a reference to a view buffer of type FloatBuffer
asDoubleBuffer() Returns a reference to a view buffer of type DoubleBuffer
asReadOnlyBuffer() Returns a reference to a read-only view buffer of type ByteBuffer
In each case, the view buffer's contents start at the current position of the original byte buffer. The posi-
tion of the view buffer itself is initially set to zero, and its capacity and limit are set to the number of bytes
remaining in the original byte buffer divided by the number of bytes in the type of element that the view
buffer holds. Figure 10-3 illustrates a view buffer of type IntBuffer that is created after the initial position
of the byte buffer has been incremented by 2, possibly after inserting a value of type char into the byte buf-
fer.
FIGURE 10-3
You can create as many view buffers from a buffer of type ByteBuffer as you want, and they can overlap
or not as you require. A view buffer always maps to bytes in the byte buffer starting at the current position.
You frequently want to map several different view buffers to a single byte buffer so that each provides a