How do Jpanel in JFrame automatically occupy all space available in JFrame in Java?

[Trenton]

Trying to create the simplest app. But when the component is added JPanel Total JFrame♪ JPanel doesn't take all the space allowed. The results of the programme are as follows: "java.awt.Dimension[width=0,height=0]"i.e. dimensions JPanel zero. How to do that Jpanelplaced in JFrame, automatically occupied everything available JFrame space Java? And could you get that dimension straight?

Programme record:

public class Test1 extends JFrame{
    Test1() {
        super("Графическое приложение");
        setBounds(50,50,1000, 450);
        JPanel panel = new JPanel();
        this.add(panel);
        System.out.println(this.getComponent(0).getSize());
    }
public static void main(String[] args) throws IOException {
   new Test1();
}

}

[simrah]

You're right in the commentary. https://ru.stackoverflow.com/users/190934/zrrr You try to run the following code:

public class Test1 extends JFrame{       
        Test1 () {
            super("Графическое приложение");
            setBounds(50,50,1000, 450);
            JPanel panel = new JPanel();
            panel.setBackground(Color.BLUE);
            this.setContentPane(panel);
        }
    public static void main(String[] args){
       Test1 test = new Test1();
       test.setVisible(true);
       System.out.println(test.getContentPane().getSize());
    }

}