Java简易计算机

为了完成Java作业，随便写了个计算器（只能简单加减乘除）

先上图

import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.Stack;
import javax.swing.JApplet;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextField;
/**
 * 
 * @author 田园小菜籽
 *
 */
public class Count extends JApplet implements ActionListener
{
    private JTextField textField = new JTextField("请输入",12);
    String operator = "";      //操作
    String input = "";        //输入的 式子
    boolean flag =  true;
    public void init()     //重写Applet里边的init方法
    {
        textField.setFont(new Font("宋体",Font.PLAIN,50));//设置字体格式
        textField.setEditable(false);           //设置文本框不可更改
        Container C = getContentPane();
        JButton b[] = new JButton[17];
        JPanel panel = new JPanel();
        JPanel panel1 = new JPanel();
        panel1.add(textField);
        panel.setLayout(new GridLayout(4, 4,5,5));
        panel1.setLayout(new FlowLayout(3));
        C.add(panel,BorderLayout.CENTER);
        C.add(panel1,BorderLayout.NORTH);
        String name[]={"7","8","9","+","4","5","6","-","1","2","3","*",".","0","=","/","C"};//设置按钮
        for(int i=0;i<17;i++)//添加按钮
        {
            b[i] = new JButton(name[i]);
            b[i].setBackground(new Color(192,192,192));
            b[i].setForeground(Color.BLACK);  //设置按键颜色
            if(i%4==3)
                b[i].setForeground(Color.RED);//设置按键颜色
            b[i].setFont(new Font("宋体",Font.PLAIN,16));//设置字体格式
            panel.add(b[i]);//将按键添加到界面
            b[i].addActionListener(this);
        }
           panel1.add(b[16]);
        b[16].setPreferredSize(new Dimension(65,65));


        b[13].setForeground(Color.RED);
    }
    public void actionPerformed(ActionEvent e)
    {
        int cnt = 0;
        String actionCommand = e.getActionCommand();
        if(actionCommand.equals("+")||actionCommand.equals("-")||actionCommand.equals("*") ||actionCommand.equals("/"))
            input +=" "+actionCommand+" ";//设置输入，把输入的样式改成 需要的样子
        else if(actionCommand.equals("C"))
            input = "";
        else if(actionCommand.equals("="))//当监听到等号时，则处理 input
        {
            input+= "="+compute(input);
            textField.setText(input);
            input="";
            cnt = 1;
        }
        else
            input += actionCommand;//数字为了避免多位数的输入 不需要加空格
        if(cnt==0)
            textField.setText(input);
    }
    /*使用栈对数据进行计算*/
    private String compute(String input)//
    {
        String str[];
        str = input.split(" ");
        Stack s = new Stack();
        double m = Double.parseDouble(str[0]);
        s.push(m);
        for(int i=1;i

ps：这个小程序拿来交个小作业还行，先说明本人打注释的习惯比较差，如要使用请自己标注释。