Question

I have defined an Activity in an Android app containing 9 button. Each button have to listen to the same event listener.

Looking at generated R class, their Ids are defined :

 public static final int btn1=0x7f040001;
 ...
 public static final int btn1=0x7f040009;

My question is: it is ok to add the listeners cycling the ID in a for loop?

for (int i= R.id.btn1; i<=R.id.btn9;i++)
{
   Button button = (Button)findViewById(i);
   button.setOnTouchListener(new View.OnTouchListener() {
        @Override public boolean onTouch(View v, MotionEvent event) {
             ...
        }
   });
}

Or there in some situation in which Id get reassigned by the compiler, breaking my code?

I’m using Intellij Idea environment to build the app.

Answer 1

I fear this would be a very bad idea in the event your R file is regenerated with non-consecutive IDs.. your better option would be to store an int array containing your IDs and loop through that

ex.

int[] views = new int[] { R.id.btn1, R.id.btn2, R.id.btn3, ...... R.id.btn9 };

for (int i= 0; i< views.length ;i++)
{
   Button button = (Button)findViewById(views[i]);
   button.setOnTouchListener(new View.OnTouchListener() {
        @Override public boolean onTouch(View v, MotionEvent event) {
             ...
        }
   });
}