问答题

本题程序的功能是使用GridBayLayout来组织窗口上的按钮。窗口中共有7个按钮，前3个按钮放置在第1排，第4个按钮独占第2排，第6个按钮位于第3排的右侧，而第5和第7个按钮共同处于第3排的左侧。请将下述程序补充完整(注意：不得改动程序的结构，不得增行或删行)。
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class simple extends Jframe

private JPanel jpanel1=new JPanel();
private GridLayout g1;
private JButton JButton1 = new JButton("第一个");
private JButton JButton2 = new JButton("第二个");
private JButton JButton3 = new JButton("第三个");
private JButton JButton4 = new JButton("第四个");
private JButton JButton5 = new JButton("第五个");
private JButton JButton6 = new JButton("第六个");
private JButton JButton7 = new JButton("第七个");
public ______()

super("simple");
setSize(300,150);
GridBagLayout gbl= ______;
jpanell.setLayout(gbl);
GridBagConstraints gbc = new GridBagConstraints();
gbc.fill = GridBagConstraints.BOTH;
gbc.gridwidth = 1;
gbc.gridheight = 1;
gbc.gridx = 0;
gbc.gridy = 0;
jpanell.add(JButtonl,gbc);
gbc.gridx = 1;
jpanell.add(JButton2,gbc);
gbc.gridx = 2;
jpanell.add(JButton3,gbc);
gbc.gridx = 0;
gbc.gridy = 1;
gbc.gridwidth = 3;
jpanell.add(JButton4,gbc);
gbc.gridy = 2;
gbc.gridwidth = 1;
jpanell.add(JButton5,gbc);
gbc.gridx = 1;
gbc.gridwidth = 2;
gbc.gridheight = 2;
jpanell.add(JButton6,gbc);
gbc.gridx = 0;
gbc.gridy = 3;
gbc.gridwidth = 1;
gbc.gridheight = 1;
jpanell.add(JButton7,gbc);
this.setContentPane (jpanel1);

public static void main (String args[])

simple fgl= new simple();
fgl.show();
fgl.addWindowListener(new WindowAdapter()
public void windowClosing(WindowEvent e)

System.exit(0);

);