How to create a custom View's layout programmatically?

Question

In an Activity, you can create a LinearLayout programmatically in the following way:

public void onCreate(Bundle savedInstanceState) {     super.onCreate(savedInstanceState);      LinearLayout ll = new LinearLayout(this);     ll.setOrientation(LinearLayout.VERTICAL);     ll.setLayoutParams(new LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT));      TextView tv1 = new TextView(this);     tv1.setText("HELLO");     ll.addView(tv1);      TextView tv2 = new TextView(this);     tv2.setText("WORLD");     ll.addView(tv2);      setContentView(ll); } 

How do you do the same inside a custom View subclass? There are no setContentView or onCreate methods...

Answer 1

Okay, I discovered one way of doing it. Basically, instead of subclassing the View class directly, you need to subclass the top-most class that you would normally define in XML. For example, if your custom View needs a LinearLayout as its top-most class, then your custom View should simply subclass LinearLayout.

For example:

public class MyCustomView extends LinearLayout {     public MyCustomView(Context context, AttributeSet attrs)     {         super(context, attrs);          setOrientation(LinearLayout.VERTICAL);         setLayoutParams(new LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT));          TextView tv1 = new TextView(context);         tv1.setText("HELLO");         addView(tv1);          TextView tv2 = new TextView(context);         tv2.setText("WORLD");         addView(tv2);     } } 

Is subclassing LinearLayout a "hack"? Not as far as I can see. Some official View subclasses do the same, like NumberPicker and SearchView (even though they inflate their layouts from XML).

Upon reflection, it's actually a pretty obvious answer.