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Bug
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Resolution: Won't Fix
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P3
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None
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1.3.0
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sparc
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solaris_2.6
Name: rlT66838 Date: 08/25/99
I'm seeing an intermittent null pointer exception when I run a
program which uses the SwingWorker class from The Swing Connection
web site:
http://java.sun.com/products/jfc/tsc/archive/tech_topics_arch/swing_worker/SwingWorker.java
It doesn't matter which compiler I've used: I tried javac from
JDK 1.2.2 and JDK 1.3, and jikes. The problem only occurs when I
use the JDK 1.3 java with HotSpot. It doesn't happen with the
JDK 1.2.2 java, nor JDK 1.3 java with the -classic flag, nor JDK
1.1.8.
It only happens *sometimes* with JDK 1.3. Here's a transcript of
some attempts showing three failures and one success:
tiffany> /opt4/jdk1.3/bin/java WorkerBug
java.lang.NullPointerException
at WorkerBug.access$000(WorkerBug.java:5)
at WorkerBug$MyWorker.construct(WorkerBug.java:34)
at SwingWorker$2.run(SwingWorker.java:101)
at java.lang.Thread.run(Thread.java:479)
tiffany> /opt4/jdk1.3/bin/java WorkerBug
java.lang.NullPointerException
at WorkerBug.access$000(WorkerBug.java:5)
at WorkerBug$MyWorker.construct(WorkerBug.java:34)
at SwingWorker$2.run(SwingWorker.java:101)
at java.lang.Thread.run(Thread.java:479)
tiffany> /opt4/jdk1.3/bin/java WorkerBug
Hello world
tiffany> /opt4/jdk1.3/bin/java WorkerBug
java.lang.NullPointerException
at WorkerBug.access$000(WorkerBug.java:5)
at WorkerBug$MyWorker.construct(WorkerBug.java:34)
at SwingWorker$2.run(SwingWorker.java:101)
at java.lang.Thread.run(Thread.java:479)
tiffany>
And here's the program:
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class WorkerBug extends JFrame {
private String query ;
public WorkerBug() {
JPanel panel = new JPanel() ;
addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent e) {
System.exit(0);
}
});
getContentPane().add(panel) ;
setBounds(200, 200, 640, 480);
setVisible(true);
}
public void doSomething() {
query = "Hello world" ;
new MyWorker() ;
}
public static void main(String s[]) {
WorkerBug wb = new WorkerBug() ;
wb.doSomething() ;
}
private class MyWorker extends SwingWorker {
public Object construct() {
System.out.println(query) ;
return query ;
}
}
}
And the JVM version:
tiffany> /opt4/jdk1.3/bin/java -version
java version "1.3beta"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.3beta-O)
Java(TM) HotSpot Client VM (build 1.3beta-O-release, 1.3beta-O-release, interpreted mode)
tiffany> /opt4/jdk1.3/bin/java -fullversion
java full version "1.3beta-O"
tiffany>
(Review ID: 94362)
======================================================================
- relates to
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JDK-4300896 Unexpected null pointer exception
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- Closed
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