/* * @(#)Runtime.java	1.3 01/08/21 * * Copyright (c) 1995-2001 Sun Microsystems, Inc. All Rights Reserved. *  * This software is the proprietary information of Sun Microsystems, Inc.   * Use is subject to license terms. *  */package java.lang;/** * Every Java application has a single instance of class  * <code>Runtime</code> that allows the application to interface with  * the environment in which the application is running. The current  * runtime can be obtained from the <code>getRuntime</code> method.  * <p> * An application cannot create its own instance of this class.  * * @author  unascribed * @version 1.53, 12/04/99 * @see     java.lang.Runtime#getRuntime() * @since   JDK1.0 */public class Runtime {    /** current runtime instance. */    private static Runtime currentRuntime = new Runtime();    /**     * Returns the runtime object associated with the current Java application.     * Most of the methods of class <code>Runtime</code> are instance      * methods and must be invoked with respect to the current runtime object.      *      * @return  the <code>Runtime</code> object associated with the current     *          Java application.     */    public static Runtime getRuntime() {         return currentRuntime;    }    /** Don't let anyone else instantiate this class */    private Runtime() {}    /**     * Terminates the currently running Java application. This     * method never returns normally.     * <p>     * This method should not be called from a MIDlet, a SecurityException     * will be the thrown if this method is called from a MIDlet.     * <p>     * The argument serves as a status code; by convention, a nonzero     * status code indicates abnormal termination.     *     * @param      status   exit status.     * @since      JDK1.0     */    public void exit(int status) {        /*         * Since we have no way of telling if this method is being called by         * a MIDlet, assume we are being called from a MIDlet and throw a         * SecurityException         */	throw new SecurityException(            "MIDP lifecycle does not support system exit.");    }    /**     * Returns the amount of free memory in the system. Calling the      * <code>gc</code> method may result in increasing the value returned      * by <code>freeMemory.</code>     *     * @return  an approximation to the total amount of memory currently     *          available for future allocated objects, measured in bytes.     */    public native long freeMemory();    /**     * Returns the total amount of memory in the Java Virtual Machine.      * The value returned by this method may vary over time, depending on      * the host environment.     * <p>     * Note that the amount of memory required to hold an object of any      * given type may be implementation-dependent.     *      * @return  the total amount of memory currently available for current      *          and future objects, measured in bytes.     */    public native long totalMemory();    /**     * Runs the garbage collector.     * Calling this method suggests that the Java Virtual Machine expend      * effort toward recycling unused objects in order to make the memory      * they currently occupy available for quick reuse. When control      * returns from the method call, the Java Virtual Machine has made      * its best effort to recycle all discarded objects.      * <p>     * The name <code>gc</code> stands for "garbage      * collector". The Java Virtual Machine performs this recycling      * process automatically as needed, in a separate thread, even if the      * <code>gc</code> method is not invoked explicitly.     * <p>     * The method {@link System#gc()} is hte conventional and convenient      * means of invoking this method.      */    public native void gc();}