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<Double> s = new Stack<Double>();        double m = Double.parseDouble(str[0]);        s.push(m);        for(int i=1;i<str.length;i++)        {            if(i%2==1)            {                if(str[i].compareTo("+")==0)                {                    double help = Double.parseDouble(str[i+1]);                    s.push(help);                }                if(str[i].compareTo("-")==0)                {                    double help = Double.parseDouble(str[i+1]);                    s.push(-help);                }                if(str[i].compareTo("*")==0)                {                    double help = Double.parseDouble(str[i+1]);                    double ans = s.peek();//取出栈顶元素                    s.pop();//消栈                    ans*=help;                    s.push(ans);                }                if(str[i].compareTo("/")==0)                {                    double help = Double.parseDouble(str[i+1]);                    double ans = s.peek();                    s.pop();                    ans/=help;                    s.push(ans);                }            }        }        double ans = 0d;        while(!s.isEmpty())        {            ans+=s.peek();            s.pop();        }        String result = String.valueOf(ans);        return result;    }    public static void main(String args[])    {        JFrame frame = new JFrame("Counter");//创建顶级窗口        frame.setResizable(false);        Count applet = new Count();        frame.getContentPane().add(applet, BorderLayout.CENTER);        applet.init();     //applet的init方法        applet.start();    //线程开始        frame.setSize(400, 450);  //设置窗口大小        frame.setVisible(true);    //设置窗口可见    }}

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。