Name: dsR10051 Date: 01/24/2001


The method
java.awt.EventQueue.invokeLater(Runnable runnable)
may not call run method of runnable if this method was
called before with null parameter.

Here is a minimized test:

import java.awt.*;
import java.awt.event.*;

public class Test02 {

    public static void main (String[] args) {
        for (int i = 0; i < 100; i++) {
            System.out.println(i);
            System.out.flush();
            EventQueue.invokeLater(null);
            MoreRunnable runnable = new MoreRunnable();
            EventQueue.invokeLater(runnable);
            try {
                runnable.WAIT();
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }
}

class MoreRunnable implements Runnable {
    public boolean run_done = false;

    public synchronized void WAIT() throws InterruptedException {
        while (!run_done) {
        System.out.println("MoreRunnable.WAIT");
        System.out.flush();
            wait();
        }
    }

    public synchronized void NOTIFY() {
        run_done = true;
        System.out.println("MoreRunnable.NOTIFY");
        System.out.flush();
        notifyAll();
    }

    public void run() {
        NOTIFY();
    }
}

--- Output ---
%java -version
java version "1.4.0-beta"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.4.0-beta-b48)
Java HotSpot(TM) Client VM (build 1.4beta-B48, mixed mode)
%java Test02
0
java.lang.NullPointerException
        at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:154)
        at java.awt.EventQueue.dispatchEvent(EventQueue.java:435)
        at java.awt.EventDispatchThread.pumpOneEvent(EventDispatchThread.java:140)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:126)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:121)
        at java.awt.EventDispatchThread.run(EventDispatchThread.java:99)
MoreRunnable.WAIT
MoreRunnable.NOTIFY
1
MoreRunnable.WAIT
java.lang.NullPointerException
        at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:154)
        at java.awt.EventQueue.dispatchEvent(EventQueue.java:435)
        at java.awt.EventDispatchThread.pumpOneEvent(EventDispatchThread.java:140)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:126)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:121)
        at java.awt.EventDispatchThread.run(EventDispatchThread.java:99)
^C%

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