What's the difference between this and Activity.this

this refers to your current object. In your case you must have implemented the intent in an inner class ClickEvent, and thats what it points to.

Activity.this points to the instance of the Activity you are currently in.

When you are pointing to this inside click event, it is pointing to the click listener.

Shubhayu's answer is correct, but I just want to make clear for anyone who see this question that this and Activity.this is the same if you are using it directly in the activity.

This is answered here

Example:

@Override
protected void onResume() {
    super.onResume();

    Log.d("Test", this.toString());
    Log.d("Test", MainActivity.this.toString());
}

Result:

D/Test: com.example.app.MainActivity@e923587
D/Test: com.example.app.MainActivity@e923587