java小程序源代码

java小程序源代码

import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;


class CalculatorPanel extends JPanel implements ActionListener
{

public CalculatorPanel()
{
setLayout(new BorderLayout());

display=new JTextField("0");
display.setEditable(false);
add(display,"Center");
ope=new JTextField(" ");
ope.setEditable(false);
add(ope,"West");
//创建菜单栏(暂时无实际意义)
JMenuBar bar=new JMenuBar();
add(bar,"North");
JMenu view=new JMenu("查看(V)");
JMenu edit=new JMenu("编辑(E)");
JMenu help=new JMenu("帮助(H)");
bar.add(view);
bar.add(edit);
bar.add(help);

JMenuItem newItem=new JMenuItem("标准型(V)");
JMenuItem newItem2=new JMenuItem("科学型(S)");
JMenuItem newItem3=new JMenuItem("退出(E)");

JMenuItem newItem4=new JMenuItem("关于..");

view.add(newItem);
view.add(newItem2);
view.add(newItem3);

help.add(newItem4);
newItem4.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent e) {

JOptionPane.showMessageDialog(null,"本程序由射手同学独立完成，请任何时候保留此句！");
}
});
newItem3.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent e) {
int res;
res=JOptionPane.showConfirmDialog(null, "确定退出？", "退出", JOptionPane.YES_NO_OPTION);
if(res==JOptionPane.YES_OPTION) System.exit(0);

}
});

JPanel p=new JPanel();
p.setLayout(new GridLayout(4,4));
String buttons="789/456*123-0.=+";
for (int i=0;i<buttons.length();i++)
addButton(p,buttons.substring(i,i+1));
add(p,"South");
}

private void addButton(Container c,String s)
{
JButton b=new JButton(s);
// b.setSize()
c.add(b);
b.addActionListener(this);
}

public void actionPerformed(ActionEvent evt)
{
String s=evt.getActionCommand();
if ('0'<=s.charAt(0)&&s.charAt(0)<='9')
{
if(start)
display.setT