Java example source code file (Starter.java)

This example Java source code file (Starter.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

classnotfoundexception, delegatingloader, interruptedexception, malformedurlexception, net, network, runnable, spawned, starter, string, thread, url

The Starter.java Java example source code

/*
 * Copyright (c) 2009, 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.
 */

import java.net.MalformedURLException;
import java.net.URL;

public class Starter implements Runnable {

    private String id;
    private DelegatingLoader dl;
    private String startClass;

    private static DelegatingLoader saLoader, sbLoader;

    public static void log(String line) {
        System.out.println(line);
    }

    public static void main(String[] args) {
        URL[] urlsa = new URL[1];
        URL[] urlsb = new URL[1];
        try {
            String testDir = System.getProperty("test.classes", ".");
            String sep = System.getProperty("file.separator");
            urlsa[0] = new URL("file://" + testDir + sep + "SA" + sep);
            urlsb[0] = new URL("file://" + testDir + sep + "SB" + sep);
        } catch (MalformedURLException e) {
            e.printStackTrace();
        }
        // Set up Classloader delegation hierarchy
        saLoader = new DelegatingLoader(urlsa);
        sbLoader = new DelegatingLoader(urlsb);

        String[] saClasses = { "comSA.SupBob", "comSA.Alice" };
        String[] sbClasses = { "comSB.SupAlice", "comSB.Bob" };

        saLoader.setDelegate(sbClasses, sbLoader);
        sbLoader.setDelegate(saClasses, saLoader);

        // test one-way delegate
        String testType = args[0];
        if (testType.equals("one-way")) {
            test("comSA.Alice", "comSA.SupBob");
        } else if (testType.equals("cross")) {
            // test cross delegate
            test("comSA.Alice", "comSB.Bob");
        } else {
            System.out.println("ERROR: unsupported - " + testType);
        }
    }

    private static void test(String clsForSA, String clsForSB) {
        Starter ia = new Starter("SA", saLoader, clsForSA);
        Starter ib = new Starter("SB", sbLoader, clsForSB);
        new Thread(ia).start();
        new Thread(ib).start();
    }

    public static void sleep() {
        try {
            Thread.sleep(500);
        } catch (InterruptedException e) {
            e.printStackTrace();
            log("Thread interrupted");
        }
    }

    private Starter(String id, DelegatingLoader dl, String startClass) {
        this.id = id;
        this.dl = dl;
        this.startClass = startClass;
    }

    public void run() {
        log("Spawned thread " + id + " running");
        try {
            // To mirror the WAS deadlock, need to ensure class load
            // is routed via the VM.
            Class.forName(startClass, true, dl);
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
        log("Thread " + id + " terminating");
    }
}