SwingWorker.java

package org.chartsy.chatsy.chat.util;

import javax.swing.SwingUtilities;

public abstract class SwingWorker
{

    private Object value;
	private ThreadVar threadVar;

    private static class ThreadVar
	{
        private Thread thread;
        ThreadVar(Thread t)
		{
            thread = t;
        }
        synchronized Thread get()
		{
            return thread;
        }
        synchronized void clear()
		{
            thread = null;
        }
    }

    protected synchronized Object getValue()
	{
        return value;
    }

    private synchronized void setValue(Object x)
	{
        value = x;
    }

    public abstract Object construct();

    public void finished()
	{
    }

    public void interrupt()
	{
        Thread t = threadVar.get();
        if (t != null)
            t.interrupt();
        threadVar.clear();
    }

    public Object get()
	{
        while (true)
		{
            Thread t = threadVar.get();
            if (t == null)
                return getValue();

            try
			{
                t.join();
            }
            catch (InterruptedException e)
			{
                Thread.currentThread().interrupt();
                return null;
            }
        }
    }

    public SwingWorker()
	{
        new Runnable()
		{
            public void run()
			{
                finished();
            }
        };

        Runnable doConstruct = new Runnable()
		{
            public void run()
			{
                try 
				{
					setValue(construct());
                }
                finally
				{
                    threadVar.clear();
                }
				
                SwingUtilities.invokeLater(new Runnable()
				{
                    public void run()
					{
                        finished();
                    }
                });

            }
        };

        Thread t = new Thread(doConstruct);
        threadVar = new ThreadVar(t);
    }

    public void start()
	{
        Thread t = threadVar.get();
        if (t != null)
            t.start();
    }
	
}