src/java.base/share/classes/java/nio/ByteOrder.java - master - githubmirror/jdk11u-dev

src/java.base/share/classes/java/nio/ByteOrder.java
95 строк3 KB
Claes Redestad
8201494: Avoid early initialization of java.nio.Bits
12 апр 2018, 18:23
12 апр 2018, 18:239ab3815
/*
 * Copyright (c) 2000, 2013, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * 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.
 */

package java.nio;

import jdk.internal.misc.Unsafe;

/**
 * A typesafe enumeration for byte orders.
 *
 * @author Mark Reinhold
 * @author JSR-51 Expert Group
 * @since 1.4
 */

public final class ByteOrder {

    private String name;

    private ByteOrder(String name) {
        this.name = name;
    }

    /**
     * Constant denoting big-endian byte order.  In this order, the bytes of a
     * multibyte value are ordered from most significant to least significant.
     */
    public static final ByteOrder BIG_ENDIAN
        = new ByteOrder("BIG_ENDIAN");

    /**
     * Constant denoting little-endian byte order.  In this order, the bytes of
     * a multibyte value are ordered from least significant to most
     * significant.
     */
    public static final ByteOrder LITTLE_ENDIAN
        = new ByteOrder("LITTLE_ENDIAN");

    // Retrieve the native byte order. It's used early during bootstrap, and
    // must be initialized after BIG_ENDIAN and LITTLE_ENDIAN.
    private static final ByteOrder NATIVE_ORDER
        = Unsafe.getUnsafe().isBigEndian()
            ? ByteOrder.BIG_ENDIAN : ByteOrder.LITTLE_ENDIAN;

    /**
     * Retrieves the native byte order of the underlying platform.
     *
     * <p> This method is defined so that performance-sensitive Java code can
     * allocate direct buffers with the same byte order as the hardware.
     * Native code libraries are often more efficient when such buffers are
     * used.  </p>
     *
     * @return  The native byte order of the hardware upon which this Java
     *          virtual machine is running
     */
    public static ByteOrder nativeOrder() {
        return NATIVE_ORDER;
    }

    /**
     * Constructs a string describing this object.
     *
     * <p> This method returns the string
     * {@code "BIG_ENDIAN"} for {@link #BIG_ENDIAN} and
     * {@code "LITTLE_ENDIAN"} for {@link #LITTLE_ENDIAN}.
     *
     * @return  The specified string
     */
    public String toString() {
        return name;
    }

}