Null pointer error when mixing JButton and PApplet.

[kvlinden]

The (stripped down) code attached below throws the following null-pointer error:

Exception in thread "Animation Thread" java.lang.NullPointerException
at processing.core.PApplet.handleDraw(PApplet.java:2301)
at processing.core.PGraphicsJava2D.requestDraw(PGraphicsJava2D.java:243)
at processing.core.PApplet.run(PApplet.java:2141)
at java.lang.Thread.run(Unknown Source)

Version information:

• Processing, v2.0b8 and later (it works with v2.0b7 and earlier).
• Java JRE 7, 1.7.0_06.

thanks,

kvlinden

------FaceController.java-------------------------------
import javax.swing.JButton;
import javax.swing.JFrame;

public class FaceController extends JFrame {

public FaceController() {
    FacePanel facePanel = new FacePanel();
    facePanel.init();
    add(facePanel);

    // Under Java jre 7 (1.7.0_06), the following JButton statement produces a null pointer error:
    //
    // Exception in thread "Animation Thread" java.lang.NullPointerException
    //         at processing.core.PApplet.handleDraw(PApplet.java:2301)
    //         at processing.core.PGraphicsJava2D.requestDraw(PGraphicsJava2D.java:243)
    //         at processing.core.PApplet.run(PApplet.java:2141)
    //         at java.lang.Thread.run(Unknown Source)
    //
    // If you remove this statement OR move it to the beginning of
    // FaceController(), the null pointer error goes away.
    //
    JButton myButton = new JButton("button");
}

public static void main(String[] args) {
    FaceController controller = new FaceController();
    controller.pack();
    // controller.setVisible(true);
}

}

------------FacePanel.java----------------------------------
import processing.core.PApplet;

public class FacePanel extends PApplet {
// Removed all this code and still got the error.
}

[aengelke]

PApplet is an Applet, so you have to call the functions to embed an Applet...

[kvlinden]

Hmm...
The code pasted above pretty much follows the example of how to embed an Applet in a SWING application shown here:

 http://processing.googlecode.com/svn/trunk/processing/build/javadoc/core/processing/core/PApplet.html

But neither my code,nor the example code (modifed a shown below) work after v2.0b7.

ideas?

kvlinden

--- Modified Embedded.java example code ----------------------------------
package work.gui;

import java.awt.BorderLayout;

import javax.swing.JButton;
import javax.swing.JFrame;

public class ExampleFrame extends JFrame {

public ExampleFrame() {
    super("Embedded PApplet");

    setLayout(new BorderLayout());
    Embedded embed = new Embedded();
    add(embed, BorderLayout.CENTER);

    // important to call this whenever embedding a PApplet.
    // It ensures that the animation thread is started and
    // that other internal variables are properly set.
    embed.init();

    // Add this button to get the null pointer error. 
    JButton myButton = new JButton("test");
}

// Add this main() method to run the application.
public static void main(String[] args) {
    ExampleFrame controller = new ExampleFrame();
    controller.pack();
    controller.setVisible(true);
}

}

[benfry]

Please use the forum for discussions; this doesn't appear to be a bug.

[kvlinden]

I see that there is a detailed discussion of this issue here:
http://forum.processing.org/topic/embedding-papplet-with-jframe-swing-error-on-jbutton
My apologies for not searching the forums more carefully.

kvlinden

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