How am I accessing my main class from an anonymous class?

Question

I thought I had a good grasp of what I was doing but whenever I feel like I have a good handle on something, I'm proven wrong :)

The code in question is this

    @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);




mButton = (Button)findViewById(R.id.m_button);
mButton.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View v) {
            // TODO Auto-generated method stub
            Intent intent = new Intent(MainActivity.this, SecondActivity.class);
            startActivity(intent);
        }
    });

    }

My confusion is in the new Intent() and startActivity method.

I was under the assumption that as long as we're working inside an anonymous class View.OnClickListener that I'd have to do something like MainActivity.this.startActivity(intent);

When I'm not inside the anonymous class, I can simply do new Intent(this,SecondActivity.class);

Can someone explain why I am able to call the startActivity(); method but can't just use this in the intent parameter?

Answer 1

In the case of the anonymous inner class this is the anonymous class itself. To access the outer class this from the anonymous one you need to do OuterClassName.this.

However an inner class is allowed to access variables and methods from the outer class. Whether the inner class is anonymous or not makes no difference what-so-ever.

See:

I thought inner classes could access the outer class variables/methods?

Java nested inner class access outer class variables

This is one of the most important differences between static and non-static inner classes.

You only need the class name if (for example) you have a method with the same name in both classes so it call tell which one you mean. That's what is happening with this, both the inner and outer class have a this - so it defaults to the inner one unless you say otherwise.

Answer 2

From your inner class you can use new Intent(MainActivity.this, AnotherActivity.class)

Because it's a this of your outer activity, not the inner class' this