How exactly does the android:onClick XML attribute differ from setOnClickListener?

Question

From that I\'ve read you can assign a onClick handler to a button in two ways.

Using the android:onClick XML attribute where you just use t

Answer 1

With Java 8, you could probably use Method Reference to achieve what you want.

Assume this is your onClick event handler for a button.

private void onMyButtonClicked(View v) {
    if (v.getId() == R.id.myButton) {
        // Do something when myButton was clicked
    }
}

Then, you pass onMyButtonClicked instance method reference in a setOnClickListener() call like this.

Button myButton = (Button) findViewById(R.id.myButton);
myButton.setOnClickListener(this::onMyButtonClicked);

This will allow you to avoid explicitly defining an anonymous class by yourself. I must however emphasize that Java 8's Method Reference is actually just a syntactic sugar. It actually create an instance of the anonymous class for you (just like lambda expression did) hence similar caution as lambda-expression-style event handler was applied when you come to the unregistering of your event handler. This article explains it really nice.

PS. For those who curious about how can I really use Java 8 language feature in Android, it is a courtesy of retrolambda library.