Does getContentPane().add() mean the same as add()

问题

Does getContentPane().add() mean the same as add() ?

public class TestFrame extends JFrame{
    public TestFrame() {
        JLabel label = new JLabel("jo");
        getContentPane().add(label);
        add(label);
    }
}

回答1:

Does getContentPane().add() mean the same as add() ?

Yes, since 1.5+.

回答2:

Mostly. To make things "easier", addImpl was changed to forward to the content pane, but in uncommon corner cases it doesn't (for instance, the content pane needs to be added somehow).

This method is overridden to conditionally forward calls to the contentPane.

回答3:

Yes, because if you notice they both are from

Class Container
java.lang.Object
  java.awt.Component
      java.awt.Container
add()

JLabel extends container and getContentPane() returns container.

来源：https://stackoverflow.com/questions/5921442/does-getcontentpane-add-mean-the-same-as-add