Java example source code file (Main.java)

This example Java source code file (Main.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.

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Java - Java tags/keywords

bytearrayinputstream, class, classloader, classnotfoundexception, concurrentlinkedqueue, file, filecacheimageinputstream, ioexception, main, myimageinputstream, override, string, test, threading, threads, throwable, util

The Main.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.
 */

package testapp;

import java.io.ByteArrayInputStream;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.util.HashMap;
import java.util.concurrent.ConcurrentLinkedQueue;
import javax.imageio.stream.FileCacheImageInputStream;
import javax.imageio.stream.ImageInputStream;

public class Main {

    public static void main(String[] args) {
        Main o = new Main("testapp.some.class", null);
        o.launch(null);
    }

    private final  String uniqClassName;
    private final ConcurrentLinkedQueue<Throwable> problems;

    public Main(String uniq, ConcurrentLinkedQueue<Throwable> p) {
        uniqClassName = uniq;
        problems = p;
    }

    public void launch(HashMap<String, ImageInputStream> refs) {
        System.out.printf("%s: current context class loader: %s\n",
                          uniqClassName,
                Thread.currentThread().getContextClassLoader());
        try {
            byte[] data = new byte[1024];
            ByteArrayInputStream bais = new ByteArrayInputStream(data);
            MyImageInputStream iis = new MyImageInputStream(bais,
                                                            uniqClassName,
                                                            problems);
            if (refs != null) {
                System.out.printf("%s: added to strong store\n",
                                  uniqClassName);
                refs.put(uniqClassName, iis);
            }
            iis.read();
            //leave stream open : let's shutdown hook work!
        } catch (IOException e) {
            problems.add(e);
        }
    }

    private static class MyImageInputStream extends FileCacheImageInputStream {
        private final String uniqClassName;
        private ConcurrentLinkedQueue<Throwable> problems;
        public MyImageInputStream(InputStream is, String uniq,
                                  ConcurrentLinkedQueue<Throwable> p) throws IOException
   {
            super(is, new File("tmp"));
            uniqClassName = uniq;
            problems = p;
        }

        @Override
        public void close() throws IOException {
            Test t = new Test();
            try {
                t.doTest(uniqClassName);
            } catch (Throwable e) {
                problems.add(e);
            }

            super.close();

            problems = null;
        }
    }
}

class Test {
    public void doTest(String uniqClassName) throws ClassNotFoundException {
        System.out.printf("%s: Current thread: %s\n", uniqClassName,
                          Thread.currentThread());

        ClassLoader thisCL = this.getClass().getClassLoader();
        Class uniq = thisCL.loadClass(uniqClassName);

        System.out.printf("%s: test is done!\n",uniqClassName);
    }
}