Java编写计算器的流程图

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class Calculator implements ActionListener
{

String s="",s1;
double d1,d2;
JFrame jf = new JFrame("小计算器by Graduate") ;

JTextField tf = new JTextField();

public void init()//实现计算器界面
{
Container c=jf.getContentPane();
tf.setHorizontalAlignment(JTextField.RIGHT);//文本框
c.add(tf,"North");

JPanel pn3 = new JPanel(new BorderLayout());
c.add(pn3,"Center");

JPanel pn2 = new JPanel();//功能键界面（清除键和关闭键）
pn2.setLayout(new BorderLayout());

JPanel pn1 = new JPanel();//运算界面

pn1.setLayout(new GridLayout(4,4));

pn3.add(pn2,"North");
pn3.add(pn1);

//设置按钮
JButton b = new JButton("CLEAR");
b.setToolTipText("请按清除键!");//设置清零键
b.setForeground(Color.RED);//设置字体颜色
b.setBackground(Color.YE