40.7 Modifying the Fragment

The fragment class now needs to be updated to react to button clicks and to interact with the data values stored in the ViewModel. The class will also need references to the three views in the user interface layout to react to button clicks, extract the current dollar value and to display the converted currency amount.

In the chapter entitled “Creating an Example Android App in Android Studio”, the onClick property of the Button widget was used to designate the method to be called when the button is clicked by the user. Unfortunately, this property is only able to call methods on an Activity and cannot be used to call a method in a Fragment. To get around this limitation, we will need to add some code to the Fragment class to set up an onClick listener on the button. The code to do this can be added to the onActivityCreated() method of the MainFragment.kt file as follows:

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import kotlinx.android.synthetic.main.main_fragment...