我如何从匿名课程访问我的主课程？

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