Java Memory Used usedMemory()

Description

Return the total memory currently in use.

License

Open Source License

Declaration

public static long usedMemory() 

Method Source Code

//package com.java2s;
/*//from w ww.  j av a 2s.  c o  m
 * Copyright 2005--2008 Helsinki Institute for Information Technology
 *
 * This file is a part of Fuego middleware.  Fuego middleware is free
 * software; you can redistribute it and/or modify it under the terms
 * of the MIT license, included as the file MIT-LICENSE in the Fuego
 * middleware source distribution.  If you did not receive the MIT
 * license with the distribution, write to the Fuego Core project at
 * fuego-core-users@googlegroups.com.
 */

public class Main {
    private static final Runtime runtime = Runtime.getRuntime();

    /**
     * Return the total memory currently in use. This method returns the
     * amount of memory (in bytes) currently used of the heap. The
     * possibility of heap size increase is taken into account.
     * The measurement is fast but may be inaccurate.
     * @see <a
     *      href="http://www.javaworld.com/javaworld/javatips/jw-javatip130.html">Java
     *      Tip 130</a>. 
     *      
     */
    public static long usedMemory() {
        return runtime.totalMemory() - runtime.freeMemory();
    }

    /** Return the total memory currently in use. This method returns the
     * amount of memory (in bytes) currently used of the heap. The
     * possibility of heap size increase is taken into account.
     * @see <a
     *      href="http://www.javaworld.com/javaworld/javatips/jw-javatip130.html">Java
     *      Tip 130</a>
     * 
     * @param accurate flag to indicate if an accurate measure should be 
     * attempted (e.g., by looping <code>gc()</code>). An accurate measurement
     * may be much slower than an inaccurate one. 
     * @return used memory
     */
    public static long usedMemory(boolean accurate) {
        if (accurate)
            runGc();
        return runtime.totalMemory() - runtime.freeMemory();
    }

    /**
     * Run the garbage collector. This method runs calls the garbage
     * collection several times to try to make sure all garbage is actually
     * collected after the method finishes.
     * @see <a
     *      href="http://www.javaworld.com/javaworld/javatips/jw-javatip130.html">Java
     *      Tip 130</a>
     */
    public static void runGc() {
        for (int i = 0; i < 4; i++) {
            _runGc();
        }
    }

    private static void _runGc() {
        long isFree = runtime.freeMemory();
        long wasFree;
        do {
            wasFree = isFree;
            runtime.runFinalization();
            runtime.gc();
            Thread.yield();
            isFree = runtime.freeMemory();
        } while (isFree > wasFree);
    }
}

Related

1. memoryUsedInMB()
2. stringMemoryUsedInMB()
3. usedMemory()
4. usedMemory()
5. usedMemory()
6. usedMemory()
7. usedMemory()
8. usedMemory(Runtime runtime)
9. usedMemoryAsString()