method calling

What would the code:

stack.top().getX() do? I mean, what would it call?

a.) call the getX() method of the result result by stack.top()
b.) call the getX() method of stack, which doesn't exist

When should I use:

stack.top().getX()

and when should I use :

(stack.top()).getX()

?

It will call the getX() of whatever top() returns

The two examples at the end of your post would have identical results

Quote:

---

Originally Posted by javapenguin

and when should I use :

(stack.top()).getX()

?

---

You only need parentheses if you need to cast the value returned by stack.top() to a Type that has the method getX().

For example, in GUI coding an event has a getSource() method that returns Object. If you know what subclass of Object is the source of the event, you can cast it accordingly to use its methods.

Code :

---

public void actionPerformed(ActionEvent e) {
  ((JButton) e.getSource()).setIcon(...);
}
// equivalent to
actionPerformed(ActionEvent e) {
  Object o = e.getSource();
  JButton button = (JButton) o;
  button.setIcon(...);
}

---

db