8029451: Tidy warnings cleanup for java.util package; minor changes in java.nio, java.sql
Reviewed-by: lancea
Contributed-by: Alexander Stepanov <alexander.v.stepanov@oracle.com>
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Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA or visit www.oracle.com if you need additional information or have any questions.--><!doctype html public "-//IETF//DTD HTML//EN"><html><body bgcolor="white">Defines buffers, which are containers for data, and provides an overview of theother 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 usedthroughout the NIO APIs. The charset API is defined in the {@linkjava.nio.charset} package, and the channel and selector APIs are defined in the{@link java.nio.channels} package. Each of these subpackages has its ownservice-provider (SPI) subpackage, the contents of which can be used to extendthe platform's default implementations or to construct alternativeimplementations.<a name="buffers"> </a><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 specificprimitive 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 reador written. The base {@link java.nio.Buffer} class defines these properties aswell 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 tothe previous mark.<p> There is a buffer class for each non-boolean primitive type. Each classdefines a family of <i>get</i> and <i>put</i> methods for moving data out ofand 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 bufferas 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 andtargets of I/O operations. They also support several features not found in theother 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 <tt>null</tt> argument to a constructoror method in any class or interface in this package will cause a {@linkjava.lang.NullPointerException NullPointerException} to be thrown.@since 1.4@author Mark Reinhold@author JSR-51 Expert Group</body></html>