PRB: Wjview.exe Causes Unhandled Exception on Handle Creation

• Microsoft Visual J++, version 6.0
• Microsoft SDK for Java, versions 3.1, 3.2
• SDK for Java, version 3.1

SYMPTOMS

If a class that extends the Window class is created with className LISTBOX and overrides wndProc() and handles the WM_CREATE message, then Wjview.exe causes an unhanded exception on handle creation.

RESOLUTION

The Window with className LISTBOX must pass the WM_CREATE message on to defWndProc() in order for the class to be created correctly.

MORE INFORMATION

Steps to Reproduce Behavior

1. Create a Java source WndTest.java:

   
   import com.ms.wfc.app.*;
   import com.ms.win32.*;
   
   public class WndTest extends Window
   {
     protected void wndProc(Message m)
      {
         switch (m.msg)
         {
           case winw.WM_CREATE:
                        break;
            default :
               defWndProc(m);
                break;
         }
      }
   } 




2. Create a Java source Form1.java:

   
   
   import com.ms.wfc.app.*;
   import com.ms.wfc.core.*;
   import com.ms.wfc.ui.*;
   import com.ms.wfc.html.*;
   import com.ms.win32.*;
   
   /**
   * This class can take a variable number of parameters on the command
   * line. Program execution begins with the main() method. The class
   * constructor is not invoked unless an object of type 'Form1' is
   * created in the main() method.
   */ 
   public class Form1 extends Form
   {
      public Form1()
      {
         // Required for Visual J++ Form Designer support
         initForm();
   
         // TODO: Add any constructor code after initForm call
      }
   
   /**
   * Form1 overrides dispose so it can clean up the
   * component list.
   */ 
      public void dispose()
      {
         super.dispose();
         components.dispose();
      }
       private void button1_click(Object source, Event e)
      {
         CreateParams cp = new CreateParams();
         cp.className = "LISTBOX";
         cp.style = winw.WS_VISIBLE;
         WndTest w = new WndTest();
         w.createHandle(cp);
      }
   
   /**
   * NOTE: The following code is required by the Visual J++ form
   * designer.  It can be modified using the form editor.  Do not
   * modify it using the code editor.
   */ 
   Container components = new Container();
   Button button1 = new Button();
   
     private void initForm()
     {
        this.setText("Form1");
        this.setAutoScaleBaseSize(new Point(5, 13));
        this.setClientSize(new Point(292, 273));
   
        button1.setLocation(new Point(112, 128));
        button1.setSize(new Point(75, 23));
        button1.setTabIndex(0);
        button1.setText("button1");
        button1.addOnClick(new EventHandler(this.button1_click));
   
        this.setNewControls(new Control[] {button1});
     }
   
   /**
   * The main entry point for the application.
   *
   * @param args Array of parameters passed to the application
   * via the command line.
   */ 
     public static void main(String args[])
     {
        Application.run(new Form1());
     }
   } 




3. Compile the Java source files.



4. Run Form1.



5. Click the button on the form. This will create a WndTest class with className LISTBOX and style WS_VISIBLE. The WndTest class overrides wndProc such that WM_CREATE is not passed on to defWndProc and everything else is.

REFERENCES

For the latest Knowledge Base articles and other support information on Visual J++ and the SDK for Java, please see the following pages on the Microsoft Technical Support site:

http://support.microsoft.com/support/visualj/

http://support.microsoft.com/support/java/

© Microsoft Corporation 1999, All Rights Reserved.
Contributions by Mohan Ananthakrishnan, Microsoft Corporation

Additional query words:

Keywords          : kbVJ600 kbWFC kbSDKJava310 kbSDKJava320 
Version           : WINDOWS:3.1,6.0
Platform          : WINDOWS 
Issue type        : kbprb 

Last Reviewed: July 9, 1999