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This article mainly explains "what are the basic knowledge of java.nio.Buffer". The content of the explanation is simple and clear, and it is easy to learn and understand. Please follow the editor's train of thought to study and learn "what is the basic knowledge of java.nio.Buffer".

Capacity (): indicates the size of the buffer. Once the size is determined, it cannot be changed.

Limit (): tells you how many bytes have been filled into the buffer so far, or use # limit (int) to change this limit

Position (): tells you the current location to perform the next read / write operation

Mark (): remember a location for later reset with reset ()

Flip (): swap limit pointers and position pointers, then set the position to 0 and discard the mark tags that have been made.

The basic operations of the buffer are reading # get () and writing # put ().

Buffer type:

NIO has seven specific Buffer types, each of which corresponds to a basic data type (except boolean)

ByteBuffer / / byte buffer CharBuffer / / character buffer DoubleBuffer / / double buffer FloatBuffer / / float buffer IntBuffer / / int buffer LongBuffer / / long buffer ShortBuffer / / short buffer

Buffers are divided into direct buffers and indirect buffers. The creation cost of direct buffers is higher than that of indirect buffers, but it also provides faster access speed. So direct buffers are suitable for long-standing buffers, while indirect buffers are suitable for those with a shorter life cycle. Also, note that only ByteBuffer can create direct buffers.

Changes in several internal states of the buffer:

Capacity (capacity), buffer size

Limit (limit), an index of * * bytes that should not be read or written, always less than the capacity.

Position, the index of the next byte to be read or written, is always less than the limit.

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