Should I call super() or call this() for android custom view constructors?

Question

When creating a custom view, I have noticed that many people seem to do it like this:

public MyView(Context context) {
  super(context);
  // this constructor used when programmatically creating view
  doAdditionalConstructorWork();
}

public MyView(Context context, AttributeSet attrs) {
  super(context, attrs);
  // this constructor used when creating view through XML
  doAdditionalConstructorWork();
}

private void doAdditionalConstructorWork() {
  // init variables etc.
}

My problem with this is that it stops me from making my variables final. Any reason not to do the following?

public MyView(Context context) {
  this(context, null);
  // this constructor used when programmatically creating view
}

public MyView(Context context, AttributeSet attrs) {
  this(context, attrs, 0);
  // this constructor used when creating view through XML
}

public MyView(Context context, AttributeSet attrs, int defStyle) {
  super(context, attrs, defStyle);
  // this constructor used where?
  // init variables
}

I've been able to create the view just fine through XML and through code, but I'm not sure if there are any drawbacks to this approach. Will this work in all cases?

There is another part to this question

Answer 1

The only drawback I can see (that no one seems to have mentioned) is that your second constructor loses the defStyle of the superclass, because you set it to zero. Look at the source code for any of Android's View classes, and you'll notice that the second constructor always has a specific defStyle defined.

For example, this is the second constructor of ListView:

public ListView(Context context, AttributeSet attrs) {
    this(context, attrs, com.android.internal.R.attr.listViewStyle);
}

If you were to extend ListView using the second approach that you describe, com.android.internal.R.attr.listViewStyle would no longer be the defStyle, because you'd be bypassing that second super constructor and making it zero instead. I suppose you could resolve this by using the same defstyle as ListView, like so:

public MyView(Context context, AttributeSet attrs) {
    this(context, attrs, android.R.attr.listViewStyle);
}

But it's not exactly the "purist" way, because you're artificially forcing it to have the same defStyle as ListView.

So, contrary to what the others said, I actually think you're better off using the first doAdditionalConstructorWork() approach outlined in your post, because that at least makes sure that the defStyle is set correctly.