11.1 Find View by ID

As outlined in the chapter entitled “The Anatomy of an Android Application”, all of the resources that make up an application are compiled into a class named R. Amongst those resources are those that define layouts. Within the R class is a subclass named layout, which contains the layout resources, including the views that make up the user interface. Most apps will need to implement interaction between the code and these views, for example when reading the value entered into the EditText view or changing the content displayed on a TextView.

Prior to the introduction of Android Studio 3.6, the only option for gaining access to a view from within the app code involved writing code to manually find a view based on its id via a method named findViewById(). For example:

TextView exampleView = findViewById(R.id.exampleView);

With the reference obtained, the properties of the view can then be accessed. For example:

exampleView.setText("Hello...