how can i remove a field from the manager in blackberry - blackberry

Question

first , please try to understand my problem because i know their are too many questions related to this , but in my case no-one is working
why i dont know , please see my code .
this is working
public final class MyScreen extends MainScreen implements FieldChangeListener
{
private combine enter_in;
private manager_s ms , ms_1 ;
private Bitmap img;
LabelField lb_1 , lb_2 , lb_3 ;
public MyScreen()
{
setTitle("MyTitle");
img = Bitmap.getBitmapResource("icon.png");
//Bitmap img_1 = Bitmap.getBitmapResource("icon.png");
enter_in = new combine ( Field.FOCUSABLE , img );
enter_in.setChangeListener(this);
ms = new manager_s( 0 , 4 );
ms.add(enter_in);
lb_1 = new LabelField("Menu") ;
lb_2 = new LabelField("Favorites") ;
lb_3 = new LabelField("Reserved") ;
ms.add(lb_1);
ms.add(lb_2);
ms.add(lb_3);
add(ms);
}
}
but when i am implementing FieldChangedListener , at that time ms.delete(lb_1) is not working but delete(ms) is working , please help solve this problem
public void fieldChanged(Field field, int context)
{
if ( field == enter_in )
{
ms.delete(lb_1);
}
}
so , i am asking that is , there any reason for ms.delete(lb_1) not working under MyScreen class .
see this is my manager_class which i am using as , Manager ( custom_manager ) and this manager is extended by my class , for adding the fields inside the screen
public class manager_s extends Manager
{
int col ;
int w_1 = 20 ;
protected manager_s(long style , int col )
{
super(style);
this.col = col ;
}
protected void sublayout(int width, int height)
{
for ( int i = 0 ; i < col ; i ++ )
{
Field field = getField (i);
layoutChild( field , 130 , 100 );
}
for ( int i = 0 ; i < col ; i ++ )
{
Field field = getField (i);
setPositionChild ( field , w_1 , 20 );
w_1 = w_1 + 135 ;
setExtent ( width , 200 );
}
}
}
and the error is INDEX_OUT_OF_BOUND_EXCEPTION , thats my question that , because every one on internet ( as a resource ) is saying that remove the field , but i my case nothing is working .

Answer 1

try this -
setTitle("MyTitle");
final ButtonField enter_in=new ButtonField("enter_in");
add(enter_in);
lb_1 = new LabelField("Menu") ;
lb_2 = new LabelField("Favorites") ;
lb_3 = new LabelField("Reserved") ;
final HorizontalFieldManager ms=new HorizontalFieldManager();
ms.add(lb_1);
lb_1.setMargin(0,50,0,0);//Here you can set the spacing between the Fields.
ms.add(lb_2);
lb_2.setMargin(0,50,0,0);//Here you can set the spacing between the Fields.
ms.add(lb_3);
add(ms);
FieldChangeListener listener=new FieldChangeListener() {
public void fieldChanged(Field field, int context) {
if(field==enter_in){
ms.delete(lb_1);
ms.invalidate();
}
}
};
enter_in.setChangeListener(listener);
In place of my ButtonField , you can use your combine.