java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.View android.app.Activity.findViewById(int)' on a null object reference

Question

I always get an Error in my Android Project.

java.lang.NullPointerException: Attempt to invoke virtual method \'android.view.View android.app.Activi

Answer 1

Use the following code:

 listView1.setOnItemClickListener(new AdapterView.OnItemClickListener() {
        @Override
        public void onItemClick(AdapterView parent, View view, int position, long id) {

       //     selectedPosition = position;

            View newTypeView=listView1.getChildAt(position-listView1.getFirstVisiblePosition()).findViewById(R.id.RelativeLayout);

            if (newTypeView.getClass().getName().toString().contains("RelativeLayout")) {


                if (lastTouchedVw != null)
                    lastTouchedVw.setBackgroundColor(Color.parseColor("#ffffff"));
                 // mainImageView.setImageURI(Uri.parse(al.get(position).toString()));
                //bigImageRelativeLayoutVw.setBackgroundColor(Color.parseColor("#ffb000"));
                    newTypeView.setBackgroundResource(R.drawable.cellbg);

                    lastTouchedVw = newTypeView;
            }