22.2 Creating Views
As previously established, the Android SDK includes a toolbox of view classes designed to meet most of the basic user interface design needs. The creation of a view in Java is simply a matter of creating instances of these classes, passing through as an argument a reference to the activity with which that view is to be associated.
The first view (typically a container view to which additional child views can be added) is displayed to the user via a call to the setContentView() method of the activity. Additional views may be added to the root view via calls to the object’s addView() method.
When working with Java code to manipulate views contained in XML layout resource files, it is necessary to obtain the ID of the view. The same rule holds true for views created in Java. As such, it is necessary to assign an ID to any view for which certain types of access will be required in subsequent Java code. This is achieved via a call to the setId() method of...
