BlackBerry Forums Support Community - NullPointerException on focusing a manager

BlackBerry Forums Support Community (http://www.blackberryforums.com/index.php)

- Developer Forum (http://www.blackberryforums.com/forumdisplay.php?f=15)

- - NullPointerException on focusing a manager (http://www.blackberryforums.com/showthread.php?t=90429)

NullPointerException on focusing a manager

Hi

As per the hierarchy manager extends Field.

So, i have overriden the drawFocus and isFocusable methods.

But whenever my isFocusable returns true for that manager, i get NullPointerException , even before its true value is set. i value is set to false, then it works fine.

I'm using the CustomManager code at BB developer site and adding drawFocus to it

Hi rock_win,

Is it possible to open your source code, so that we can point to your interest?

Thanks,
ARIF

Heres the code, as soon as i set _focusable to true, i get the exception

Code:

import net.rim.device.api.ui.*;

import net.rim.device.api.ui.component.*;

import net.rim.device.api.ui.container.*;

import net.rim.device.api.system.*;









class MainFrame extends Manager{

    public boolean _focusable=false;

    boolean extent1=true;

    int _width=0,_height=0;//for width and height of individual field

        int x=0,y=0;//for each field

        

    

    MainFrame(int x,int y,int _width,int _height) { 

     super(Manager.VERTICAL_SCROLL|Manager.FOCUSABLE);

     this.x=x;

     this.y=y;

     this._width=_width;

     this._height=_height;

       }

    

    public int getPreferredWidth()

    {

        return 260;

    }

    public int getPreferredHeight()

    {

        return 160;

    }

    

        public void sublayout(int width,int height)

    {

        System.out.println("width:"+width+"\t height:"+height);

        Field field;

        int noFields=getFieldCount();     

        

     

        for(int i=0;i<noFields;i++)

        {

             field=getField(i);

            setPositionChild(field,10,10+y);

        

if(field instanceof CustomRectField){

    System.out.println("Drawing RectField"+getExtent().width+"\t"+getExtent().height);

             x=((CustomRectField)field).x;

                y=((CustomRectField)field).y;

                _width=((CustomRectField)field)._width;

                _height=((CustomRectField)field)._height;

              setPositionChild(field,x,y);

        }

            layoutChild(field,_width,_height);

            //y+=30;

        }

      

   setExtent(getPreferredWidth(),getPreferredHeight());

   

    }

  public boolean isFocusable()

    {

        return _focusable;

    }

   

}

This is totally a guess but the manager class might not like being constructed with Manager.FOCUSABLE while returning false (from public boolean _focusable=false; , return _focusable) via your overriding isFocusable method.

Figured out the problem, it was the problem the fields are getting added in, at the time isFocusable is called the managers are empty