setExtendedState(MAXIMIZED_BOTH)竟然没用呀?为什么?各位帮手解答一下啦!(100分)

import java.awt.*;
import javax.swing.*;
import javax.swing.UIManager;
public class MaxWindowTest extends JFrame {
public MaxWindowTest()
{
JFrame aframe = new JFrame();
aframe.setTitle("HEllo");
aframe.setExtendedState(MAXIMIZED_BOTH);
aframe.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
aframe.setVisible(true);

}
public static void main(String[] prgs)
{
new MaxWindowTest();
}
}