功能举例：
源程序如下：
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public class Calucator extends JFrame {
private JTextField tf;
private JPanel panel1, panel2, panel3, panel4;
private JMenuBar myBar;
private JMenu menu1, menu2, menu3;
private JMenuItem editItem1, editItem2, help1, help2, help3;
private JRadioButtonMenuItem seeItem1, seeItem2;###");, new Dot(), ;
addButton(panel2, "+", new Signs(), ;
addButton(panel2, "tan", new Signs(), ;
addButton(panel2, "%", new Signs(), ;
addButton(panel2, "π", numActionListener, ;
addButton(panel2, "e", numActionListener, ;
addButton(panel2, "′″", new Signs(), ;
addButton(panel2, "=", new Signs(), ;
JButton btns = new JButton("计算器"); createLoweredBevelBorder());
false);rim());
(i));
}else if(str == "Backspace"){
if()) > 0){
if().length() > 1){
().substring(0, ().length() - 1));
ength() > 2){
().substring(0, ().length() - 1));
}else{
("0");
IfResult = true;
}
}
}else if(str == "CE"){
("0");
IfResult = true;
}
}
}
/**
*数字输入的事件监听
*/
class Num implements ActionListener{
public void actionPerformed(ActionEvent e) { if(IfResult){
("");
IfResult = false;
}
if(str=="π")
{
);
}
else if(str=="e")
{
);
}
else{
().trim() + str);
if().equals("0")){
("0");
IfResult = true;
flag = true;
}
}
}
}
/**
*小数点的事件监听
*/
class Dot implements ActionListener{
public void actionPerformed(ActionEvent e) { IfResult = false;
if().trim().indexOf(".") == -1){
() + ".");
}
}
}
/**
*main方法
*/
public static void main(String[] args) { new Calucator().setVisible(true);
}
}。