1 /*
   2  * Copyright (c) 1998, 2006, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 
  26 /**
  27  * Provides classes that are fundamental to the design of the Java
  28  * programming language. The most important classes are {@code
  29  * Object}, which is the root of the class hierarchy, and {@code
  30  * Class}, instances of which represent classes at run time.
  31  *
  32  * <p>Frequently it is necessary to represent a value of primitive
  33  * type as if it were an object. The wrapper classes {@code Boolean},
  34  * {@code Character}, {@code Integer}, {@code Long}, {@code Float},
  35  * and {@code Double} serve this purpose.  An object of type {@code
  36  * Double}, for example, contains a field whose type is double,
  37  * representing that value in such a way that a reference to it can be
  38  * stored in a variable of reference type.  These classes also provide
  39  * a number of methods for converting among primitive values, as well
  40  * as supporting such standard methods as equals and hashCode.  The
  41  * {@code Void} class is a non-instantiable class that holds a
  42  * reference to a {@code Class} object representing the type void.
  43  *
  44  * <p>The class {@code Math} provides commonly used mathematical
  45  * functions such as sine, cosine, and square root. The classes {@code
  46  * String}, {@code StringBuffer}, and {@code StringBuilder} similarly
  47  * provide commonly used operations on character strings.
  48  *
  49  * <p>Classes {@code ClassLoader}, {@code Process}, {@code
  50  * ProcessBuilder}, {@code Runtime}, {@code SecurityManager}, and
  51  * {@code System} provide "system operations" that manage the dynamic
  52  * loading of classes, creation of external processes, host
  53  * environment inquiries such as the time of day, and enforcement of
  54  * security policies.
  55  *
  56  * <p>Class {@code Throwable} encompasses objects that may be thrown
  57  * by the {@code throw} statement. Subclasses of {@code Throwable}
  58  * represent errors and exceptions.
  59  *
  60  * <a name="charenc"></a>
  61  * <h3>Character Encodings</h3>
  62  *
  63  * The specification of the {@link java.nio.charset.Charset
  64  * java.nio.charset.Charset} class describes the naming conventions
  65  * for character encodings as well as the set of standard encodings
  66  * that must be supported by every implementation of the Java
  67  * platform.
  68  *
  69  * @since 1.0
  70  */
  71 package java.lang;