/* * Copyright (c) 1998, 2006, 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. */ /** * Provides classes that are fundamental to the design of the Java * programming language. The most important classes are {@code * Object}, which is the root of the class hierarchy, and {@code * Class}, instances of which represent classes at run time. * *
Frequently it is necessary to represent a value of primitive * type as if it were an object. The wrapper classes {@code Boolean}, * {@code Character}, {@code Integer}, {@code Long}, {@code Float}, * and {@code Double} serve this purpose. An object of type {@code * Double}, for example, contains a field whose type is double, * representing that value in such a way that a reference to it can be * stored in a variable of reference type. These classes also provide * a number of methods for converting among primitive values, as well * as supporting such standard methods as equals and hashCode. The * {@code Void} class is a non-instantiable class that holds a * reference to a {@code Class} object representing the type void. * *
The class {@code Math} provides commonly used mathematical * functions such as sine, cosine, and square root. The classes {@code * String}, {@code StringBuffer}, and {@code StringBuilder} similarly * provide commonly used operations on character strings. * *
Classes {@code ClassLoader}, {@code Process}, {@code * ProcessBuilder}, {@code Runtime}, {@code SecurityManager}, and * {@code System} provide "system operations" that manage the dynamic * loading of classes, creation of external processes, host * environment inquiries such as the time of day, and enforcement of * security policies. * *
Class {@code Throwable} encompasses objects that may be thrown * by the {@code throw} statement. Subclasses of {@code Throwable} * represent errors and exceptions. * * *