1.下面两部分英文原文及其翻译适用于本教程中绝大部分页面，如有出入，请以甲骨文公司官方提供的Java教程为准：
    The Java Tutorials have been written for JDK 8. Examples and practices described in this page don’t take advantage of improvements introduced in later releases and might use technology no longer available.
    See JDK Release Notes for information about new features, enhancements, and removed or deprecated options for all JDK releases.
    Java教程是为JDK 8编写的。本页面中描述的示例和实践可能没有利用更高版本中引入的改进，因此可能会使用不再可用的技术。
    有关所有JDK版本的新功能，增强功能以及已删除或不建议使用的选项的信息，请参见JDK发行说明。
    2.在使用本教程中的代码时，请注意代码的使用说明，例如：

    1. /*
    2.  * Copyright (c) 2013, Oracle and/or its affiliates. All rights reserved.
    3.  *
    4.  * Redistribution and use in source and binary forms, with or without
    5.  * modification, are permitted provided that the following conditions
    6.  * are met:
    7.  *
    8.  *   - Redistributions of source code must retain the above copyright
    9.  *     notice, this list of conditions and the following disclaimer.
    10.  *
    11.  *   - Redistributions in binary form must reproduce the above copyright
    12.  *     notice, this list of conditions and the following disclaimer in the
    13.  *     documentation and/or other materials provided with the distribution.
    14.  *
    15.  *   - Neither the name of Oracle or the names of its
    16.  *     contributors may be used to endorse or promote products derived
    17.  *     from this software without specific prior written permission.
    18.  *
    19.  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
    20.  * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
    21.  * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
    22.  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR
    23.  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
    24.  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
    25.  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
    26.  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
    27.  * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
    28.  * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
    29.  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
    30.  */

    3.下载使用JDK时，请注意不同JDK的使用协议：
    Oracle OpenJDK——Oracle的免费GPL许可（ GNU General Public License, version 2, with the Classpath Exception），可用于生产环境；
    Oracle JDK——Oracle的商业许可（Oracle Technology Network License）。
    简单来说，Oracle OpenJDK就是免费，但后续没有后续支持服务，只能安装最新的Oracle OpenJDK以解决问题；而Oracle JDK就是商用收费，有后续的技术服务支持，一个版本可以用很长时间。两者在功能上没有太大差异，根据自身的实际情况进行选择。