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| <!doctype html public "-//IETF//DTD HTML//EN"> |
| <html> |
| <body bgcolor="white"> |
| |
| 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 <tt>java.nio</tt> 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 name="buffers"> |
| |
| <blockquote><table cellspacing=1 cellpadding=0 summary="Description of the various buffers"> |
| <tr><th><p align="left">Buffers</p></th><th><p align="left">Description</p></th></tr> |
| <tr><td valign=top><tt>{@link java.nio.Buffer}</tt></td> |
| <td>Position, limit, and capacity; |
| <br>clear, flip, rewind, and mark/reset</td></tr> |
| <tr><td valign=top><tt> {@link java.nio.ByteBuffer}</tt></td> |
| <td>Get/put, compact, views; allocate, wrap</td></tr> |
| <tr><td valign=top><tt> {@link java.nio.MappedByteBuffer} </tt></td> |
| <td>A byte buffer mapped to a file</td></tr> |
| <tr><td valign=top><tt> {@link java.nio.CharBuffer}</tt></td> |
| <td>Get/put, compact; allocate, wrap</td></tr> |
| <tr><td valign=top><tt> {@link java.nio.DoubleBuffer}</tt></td> |
| <td> ' '</td></tr> |
| <tr><td valign=top><tt> {@link java.nio.FloatBuffer}</tt></td> |
| <td> ' '</td></tr> |
| <tr><td valign=top><tt> {@link java.nio.IntBuffer}</tt></td> |
| <td> ' '</td></tr> |
| <tr><td valign=top><tt> {@link java.nio.LongBuffer}</tt></td> |
| <td> ' '</td></tr> |
| <tr><td valign=top><tt> {@link java.nio.ShortBuffer}</tt></td> |
| <td> ' '</td></tr> |
| <tr><td valign=top><tt>{@link java.nio.ByteOrder}</tt></td> |
| <td>Typesafe enumeration for byte orders</td></tr> |
| </table></blockquote> |
| |
| <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 </code><i>mapping</i><code>} 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">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 <tt>null</tt> 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 |
| |
| </body> |
| </html> |
