java編程作業，求答案

import java.awt.*;

import java.awt.event.WindowAdapter;

import java.awt.event.WindowEvent;

public class fix extends Frame {

public fix() {

super("姓名:XXX");

field = new TextField();

Panel center = new Panel(new GridLayout(4, 4));

buttons = new Button[16];

for(int i = 0 ; i <16;i++){

buttons[i] = new Button(Integer.toHexString(i).toUpperCase());

center.add(buttons[i]);

}

this.add(field,BorderLayout.NORTH);

this.add(center,BorderLayout.CENTER);

this.setSize(250, 200);

this.addWindowListener(new WindowAdapter() {

@Override

public void windowClosing(WindowEvent e) {

dispose();

}

});

}

public static void main(String[] args) {

new fix().setVisible(true);

}

private TextField field;

private Button[] buttons;

}