Android™ How to Program, Second Edition

Registering the Event Listeners

Lines 60–61 get a reference to the amountEditText, and line 62 calls its addTextChanged-Listener method to register the TextChangedListener that will respond to events generated when the user changes the text in the EditText. We define this listener (Fig. 3.16) as an anonymous-inner-class object that’s assigned to the instance variable amountEditTextWatcher.

Lines 65–66 get a reference to the customTipSeekBar and line 67 calls its setOnSeekBarChangeListener method to register the OnSeekBarChangeListener that will respond to events generated when the user moves the customTipSeekBar’s thumb to change the custom tip percentage. We define this listener (Fig. 3.15) as an anonymous-inner-class object that’s assigned ...