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Defines buffers, which are containers for data, and provides an
overview of the other NIO packages.
The central abstractions of the NIO APIs are:
Buffers, which are containers for data;
Charsets and their
associated decoders and encoders,
which
translate between bytes and Unicode characters;
Channels of
various types, which represent connections
to entities
capable of performing I/O operations; and
Selectors and selection keys, which
together with
selectable channels define a multiplexed,
non-blocking
I/O facility.
The java.nio package defines the buffer classes, which are used throughout the NIO APIs. The charset API is defined in the charset package, and the channel and selector APIs are defined in the channels package. Each of these subpackages has its own service-provider (SPI) subpackage, the contents of which can be used to extend the platform's default implementations or to construct alternative implementations.
Description of the various buffers
Buffers
Description BufferPosition, limit, and capacity;
clear, flip, rewind, and mark/reset
ByteBuffer
Get/put, compact, views; allocate, wrap
MappedByteBuffer
A byte buffer mapped to a file
CharBuffer
Get/put, compact; allocate, wrap
DoubleBuffer
Get/put, compact; allocate, wrap
FloatBuffer
Get/put, compact; allocate, wrap
IntBuffer
Get/put, compact; allocate, wrap
LongBuffer
Get/put, compact; allocate, wrap
ShortBuffer
Get/put, compact; allocate, wrap ByteOrderTypesafe enumeration for byte orders
A buffer is a container for a fixed amount of data of a
specific primitive type. In addition to its content a buffer has a
position, which is the index of the next element to be read
or written, and a limit, which is the index of the first element that should not be read or written. The base Buffer class defines these properties as well as methods for clearing, flipping, and rewinding, for
marking the current position, and for resetting the
position to the previous mark.
There is a buffer class for each non-boolean primitive type.
Each class defines a family of get and put methods
for moving data out of and in to a buffer, methods for
compacting, duplicating, and slicing a buffer,
and static methods for allocating a new buffer as well as
for wrapping an existing array into a buffer.
Byte buffers are distinguished in that they can be used as the
sources and targets of I/O operations. They also support several
features not found in the other buffer classes:
A byte buffer can be allocated as a direct buffer, in which
case the Java virtual machine will make a best effort to perform
native I/O operations directly upon it.
A byte buffer can be created by mapping a region of a file directly into memory, in which case a few additional file-related operations defined in the MappedByteBuffer class are available.
A byte buffer provides access to its content as either a
heterogeneous or homogeneous sequence of binary data of any
non-boolean primitive type, in either big-endian or little-endian
byte order.
Unless otherwise noted, passing a null argument to a constructor or method in any class or interface in this package will cause a
NullPointerException to be thrown.
Author: Mark Reinhold, JSR-51 Expert Group Since: 1.4
/**
* Defines buffers, which are containers for data, and provides an
* overview of the other NIO packages.
*
*
* <p> The central abstractions of the NIO APIs are: </p>
*
* <ul>
*
* <li><p> <a href="#buffers"><i>Buffers</i></a>, which are containers for data;
* </p></li>
*
* <li><p> <a
* href="charset/package-summary.html"><i>Charsets</i></a> and their
* associated <i>decoders</i> and <i>encoders</i>, <br> which
* translate between bytes and Unicode characters; </p></li>
*
* <li><p> <a
* href="channels/package-summary.html"><i>Channels</i></a> of
* various types, which represent connections <br> to entities
* capable of performing I/O operations; and </p></li>
*
* <li><p> <i>Selectors</i> and <i>selection keys</i>, which
* together with <br> <i>selectable channels</i> define a <a
* href="channels/package-summary.html#multiplex">multiplexed,
* non-blocking <br> I/O</a> facility. </p></li>
*
* </ul>
*
* <p> The {@code java.nio} package defines the buffer classes, which
* are used throughout the NIO APIs. The charset API is defined in
* the {@link java.nio.charset} package, and the channel and selector
* APIs are defined in the {@link java.nio.channels} package. Each of
* these subpackages has its own service-provider (SPI) subpackage,
* the contents of which can be used to extend the platform's default
* implementations or to construct alternative implementations.
*
* <a id="buffers"> </a>
*
* <table class="striped" style="margin-left:2em; text-align:left">
* <caption style="display:none">Description of the various buffers</caption>
* <thead>
* <tr><th scope="col">Buffers</th>
* <th scope="col">Description</th></tr>
* </thead>
* <tbody>
* <tr><th scope="row">{@link java.nio.Buffer}</th>
* <td>Position, limit, and capacity;
* clear, flip, rewind, and mark/reset</td></tr>
* <tr><th scope="row">
* <span style="padding-left:1em">{@link java.nio.ByteBuffer}</span></th>
* <td>Get/put, compact, views; allocate, wrap</td></tr>
* <tr><th scope="row">
* <span style="padding-left:2em">{@link java.nio.MappedByteBuffer}</span></th>
* <td>A byte buffer mapped to a file</td></tr>
* <tr><th scope="row">
* <span style="padding-left:1em">{@link java.nio.CharBuffer}</span></th>
* <td>Get/put, compact; allocate, wrap</td></tr>
* <tr><th scope="row">
* <span style="padding-left:1em">{@link java.nio.DoubleBuffer}</span></th>
* <td>Get/put, compact; allocate, wrap</td></tr>
* <tr><th scope="row">
* <span style="padding-left:1em">{@link java.nio.FloatBuffer}</span></th>
* <td>Get/put, compact; allocate, wrap</td></tr>
* <tr><th scope="row">
* <span style="padding-left:1em">{@link java.nio.IntBuffer}</span></th>
* <td>Get/put, compact; allocate, wrap</td></tr>
* <tr><th scope="row">
* <span style="padding-left:1em">{@link java.nio.LongBuffer}</span></th>
* <td>Get/put, compact; allocate, wrap</td></tr>
* <tr><th scope="row">
* <span style="padding-left:1em">{@link java.nio.ShortBuffer}</span></th>
* <td>Get/put, compact; allocate, wrap</td></tr>
* <tr><th scope="row">{@link java.nio.ByteOrder}</th>
* <td>Typesafe enumeration for byte orders</td></tr>
* </tbody>
* </table>
*
* <p> A <i>buffer</i> is a container for a fixed amount of data of a
* specific primitive type. In addition to its content a buffer has a
* <i>position</i>, which is the index of the next element to be read
* or written, and a <i>limit</i>, which is the index of the first
* element that should not be read or written. The base {@link
* java.nio.Buffer} class defines these properties as well as methods
* for <i>clearing</i>, <i>flipping</i>, and <i>rewinding</i>, for
* <i>marking</i> the current position, and for <i>resetting</i> the
* position to the previous mark.
*
* <p> There is a buffer class for each non-boolean primitive type.
* Each class defines a family of <i>get</i> and <i>put</i> methods
* for moving data out of and in to a buffer, methods for
* <i>compacting</i>, <i>duplicating</i>, and <i>slicing</i> a buffer,
* and static methods for <i>allocating</i> a new buffer as well as
* for <i>wrapping</i> an existing array into a buffer.
*
* <p> Byte buffers are distinguished in that they can be used as the
* sources and targets of I/O operations. They also support several
* features not found in the other buffer classes:
*
* <ul>
*
* <li><p> A byte buffer can be allocated as a <a
* href="ByteBuffer.html#direct"> <i>direct</i></a> buffer, in which
* case the Java virtual machine will make a best effort to perform
* native I/O operations directly upon it. </p></li>
*
* <li><p> A byte buffer can be created by {@link
* java.nio.channels.FileChannel#map <i>mapping</i>} a region of a
* file directly into memory, in which case a few additional
* file-related operations defined in the {@link
* java.nio.MappedByteBuffer} class are available. </p></li>
*
* <li><p> A byte buffer provides access to its content as either a
* heterogeneous or homogeneous sequence of <a
* href="ByteBuffer.html#bin"><i>binary data</i></a> of any
* non-boolean primitive type, in either big-endian or little-endian
* <a href="ByteOrder.html">byte order</a>. </p></li>
*
* </ul>
*
* <p> Unless otherwise noted, passing a {@code null} argument to a
* constructor or method in any class or interface in this package
* will cause a {@link java.lang.NullPointerException
* NullPointerException} to be thrown.
*
* @since 1.4
* @author Mark Reinhold
* @author JSR-51 Expert Group
*/
package java.nio;