PRB: Scroll Box Jumps Up and Down in UIColumnViewer Class Object (238830)

MORE INFORMATION

Steps to Reproduce the Behavior

1. Create a new program named TestViewer.java. This program creates a Frame with a table that contains five columns and one hundred rows. Because the data exceeds the size of the frame window, the program creates a scroll bar so that you can position the contents for viewing. Additionally, the program creates a timer thread to update the contents of the rows every three seconds.
   
   In TestViewer.java, paste the following code:

   import java.awt.*;
   import com.ms.ui.*;
   
   public class TestViewer
   {
      private static TestFrame tframe = null;
   	
      public static void main(String args[])
      {
         tframe = new TestFrame();
         tframe.initialize();
      }		
   }
   	
   class TestFrame extends UIFrame
   {
      private UIList         list         = null;
      private UpdateThread   updateThread = null;
      private int            iColumns     = 5;
      private int            iRows        = 100;
      private UIColumnViewer viewer       = null;
      private boolean        bToggle      = true;
   
   
      public TestFrame()
      {
         super("UIColumnViewer Scroll Bar update test");
      }
   			
      public void initialize()
      {			
         UIColumnHeader[] hdrs = new UIColumnHeader[]
         {
            new UIColumnHeader("Col 1"),
            new UIColumnHeader("Col 2"),
            new UIColumnHeader("Col 3"),
            new UIColumnHeader("Col 4"),
            new UIColumnHeader("Col 5")
         };
   
         setSize(600, 400);
         list = new UIList();
         viewer = new UIColumnViewer(hdrs, list);
         viewer.setWidths( (600/iColumns)-7 );
   
         UIPanel panel = new UIPanel();
         panel.setLayout(new UIBorderLayout());
   			
         panel.add(viewer, "center");
         add(panel);
         show();
         refresh();
         startRefresh();		
      }
   		
      private void startRefresh()
      {
         // WORKAROUND
         // Comment out this line to apply workaround.
         updateThread = new  UpdateThread(this);
      }
   		
      public void refresh()
      { 
         while (list.getChildCount() > 0) list.remove(0);
   
         viewer.paint(this.getGraphics());
         for (int i=0; i < iRows; i++)
         {
            //Each row is made up of an array of Strings. 
            Object[] rowObjs = new Object[iColumns];	
            for (int j=0; j < iColumns; j++)
            {
               // Just to update the rows with different
               // data in alternate cycles.
               if( bToggle )
                  rowObjs[j] = new UIText("Data" + i + j, UIText.CENTERED);
               else
                  rowObjs[j] = new UIText("Data" + j + i, UIText.CENTERED);
            }	
            UIRow row = new UIRow(rowObjs);	
            viewer.add(row);
         }
         if( bToggle )
            bToggle = false;
         else
            bToggle = true;
         }
   
      public boolean handleEvent(Event e)
      {
         switch(e.id)
         {
            case Event.WINDOW_DESTROY:
               System.exit(0);
               return true;
           default:
               return super.handleEvent(e);
         }
      }	
   }
   	
   // This thread updates the list periodically:
   // class UpdateThread extends Thread.
   {
      private TestFrame pFrame = null;
   			
      UpdateThread(TestFrame newFrame)
      {
         pFrame = newFrame;
         start();
      }
   
      public void run()
      {
         for (;;)
         {
            pFrame.refresh();
            try { sleep(3000); }
            catch (InterruptedException ex) { }
         }
      }
   }
   					

2. At a command prompt, type the following command to compile TestViewer.java:

   jvc TestViewer.java

3. At a command prompt, type the following command to run the TestViewer.class file:

   jview TestViewer.class

4. Use the thumb to scroll up and down. You can scroll properly until the contents are updated (about every 3 seconds), at which time the scrolling thumb jumps up and down in the scroll bar.