Question

I am not understanding the concept of final variable. In a for loop I have dynamic variable i which is crucial for me to refer an array. As soon as I use i, it throws me an error saying it should be final.

What exactly is final? Could you please help to get rid of that error?

My code is here:

for( int i = 0; i <4; i++)
{

   Bitmap celeb1=Bitmap.getBitmapResource(fimagearray[i]);
   Bitmap celeb1_focus=Bitmap.getBitmapResource(fimagearray[i]);
   ImageButton celebbutton = new ImageButton(celeb1, celeb1_focus);

   celebbutton.setChangeListener(new FieldChangeListener() {

       public void fieldChanged(Field field, int context) 
       {
           UiApplication.getUiApplication().pushScreen(new FetchTweets(fusernamearray[i]));

       }
   });


   femaleSec.add(celebbutton);
}

Answer 1

An anonymous inner class can only access final variables from the outer scope. Since i is not final, it can’t be accessed directly. You can’t make i final since it needs to change, and a final variable can’t be changed.

As a simple workaround, copy the value of i into a final variable during each loop iteration:

for( int i = 0; i < 4; i++)
{
    final int index = i; // <-- copy i to `index' to use in FieldChangeListener

    // ...

    celebbutton.setChangeListener(new FieldChangeListener() {

        public void fieldChanged(Field field, int context) 
        {
            UiApplication.getUiApplication().pushScreen(
               new FetchTweets(fusernamearray[index])); // <-- `index'
        }
    });


    femaleSec.add(celebbutton);
}