Setting and removing bitmap for button onfocus and onUnfocus

How to place bitmapFields in Manager while some buttons on it get focus.I tried following code but it is not working.`

when "button" get focus I need to add "field1" beside the button in Vfm.

button = new ImgButtonField("res/images/trans.png", Field.FOCUSABLE){
            protected void onFocus(int direction) {  
              Vfm.insert(field1, button.getIndex()) ;
                   super.onFocus(direction);
                   invalidate();
开发者_JS百科                }
             protected void onUnfocus() {
                    Vfm.delete(field1);
                   super.onUnfocus();
                   invalidate();
             }      
        };

Try using add rather than insert ,sample code i tried

ButtonField button,button1;
LabelField field1;
VerticalFieldManager vfm;
public MyScreen()
{        
    // Set the displayed title of the screen       
    setTitle("MyTitle");
    vfm=new VerticalFieldManager();
    field1=new LabelField("Sample");
    button=new ButtonField("Sample"){

        protected void onFocus(int direction) {  
                vfm.add(field1);
                 super.onFocus(direction);
                 invalidate();
              }
           protected void onUnfocus() {
                  vfm.delete(field1);
                 super.onUnfocus();
                 invalidate();
           }      

    };
    button1=new ButtonField("Sampl1");
    this.add(button1);
    this.add(button);
    this.add(vfm);

}

Regards Rakesh Shankar.P

Try placing a NullField in the manager as a placeholder. The NullField will not be visible. On focus, you can replace that NullField with field1.

   NullField myNullField = new NullField(); 
   button = new ImgButtonField("res/images/trans.png", Field.FOCUSABLE){
                protected void onFocus(int direction) {  
                       Vfm.replace(myNullField, field1) ;
                       super.onFocus(direction);
                       invalidate();
                    }
                 protected void onUnfocus() {
                       Vfm.replace(field1, myNullField);
                       super.onUnfocus();
                       invalidate();
                 }      
            };
   //add fields to Vfm, including the myNullField placeholder.