update textview without any buttons

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http://stackoverflow.com – I have 2 edittext fields empty and i want to when i type numbers inside the two fields a 3rd textview will automatically get the division of the 2 above edittexts. So no buttons to calculate that etc. The thing is when i enter one number on any field the app gets force closed. Here is my code and the logcat: amount.addTextChangedListener(new TextWatcher() { public void afterTextChanged(Editable arg0) { } public void beforeTextChanged(CharSequence s, int start, int count, int after) { } public void onTextChanged(CharSequence s, i (HowTos)