Java example source code file (GetInitializedClassCount.java)

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Java - Java tags/keywords

classtoinitialize0, getinitializedclasscount, hotspotclassloadingmbean, initialized, max_value_for_pass, min_value_for_pass, runtimeexception

The GetInitializedClassCount.java Java example source code

/*
 * Copyright (c) 2003, 2013, 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.
 *
 * 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.
 */

/*
 * @test
 * @bug     4858522
 * @summary Basic unit test of HotspotClassLoadingMBean.getInitializedClassCount()
 * @author  Steve Bohne
 * @run main/othervm -XX:+UsePerfData GetInitializedClassCount
 */

/*
 * This test is just a sanity check and does not check for the correct value.
 */

import sun.management.*;

public class GetInitializedClassCount {

    private static HotspotClassLoadingMBean mbean =
        (HotspotClassLoadingMBean)ManagementFactoryHelper.getHotspotClassLoadingMBean();

    // Careful with these values.
    private static final long MIN_VALUE_FOR_PASS = 1;
    private static final long MAX_VALUE_FOR_PASS = Long.MAX_VALUE;

    private static boolean trace = false;

    public static void main(String args[]) throws Exception {
        if (args.length > 0 && args[0].equals("trace")) {
            trace = true;
        }

        long value = mbean.getInitializedClassCount();

        if (trace) {
            System.out.println("Initialized class count: " + value);
        }

        if (value < MIN_VALUE_FOR_PASS || value > MAX_VALUE_FOR_PASS) {
            throw new RuntimeException("Initialized class count " +
                                       "illegal value: " + value + " " +
                                       "(MIN = " + MIN_VALUE_FOR_PASS + "; " +
                                       "MAX = " + MAX_VALUE_FOR_PASS + ")");
        }

        // Initialize a class
        Class.forName("ClassToInitialize0");

        long value2 = mbean.getInitializedClassCount();

        if (trace) {
            System.out.println("Initialized class count2: " + value2);
        }

        // If new count does not reflect that at least one class has
        // been initialized, throw an exception.  We don't check that
        // _exactly_ one class has been initialized because another
        // thread may (rarely) have also done some class initialization.
        if (value2 < value + 1) {
            throw new RuntimeException("Initialized class count " +
                                       "did not increase " +
                                       "(value = " + value + "; " +
                                       "value2 = " + value2 + ")");
        }

        System.out.println("Test passed.");
    }
}

class ClassToInitialize0 {
    static int i = 0;
    static {
        i = 1;
    }
}