java 简单计算器

Posted 2023-02-14 xiaoxiaodeyan

package mdthob;//package com.cal;

import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.Stack;
import javax.swing.*;

class MyException extends Exception
    public MyException(String message) 
        super(message);
    


class SwingConsole
    public static void run(final JFrame f,final int width,final int height)
        SwingUtilities.invokeLater(() -> 
            f.setTitle(f.getClass().getSimpleName());
            f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
            f.setSize(width,height);
            f.setVisible(true);
        );
    


public class MyCalculator extends JFrame
    /*
     *
     */

    private final JTextField textField;             //输入文本框
    private String input;                 //结果

    public MyCalculator() 
        input = "";
        //操作符

        Container container = this.getContentPane();
        JPanel panel = new JPanel();
        textField = new JTextField(30);
        textField.setEditable(false);                 //文本框禁止编辑
        textField.setHorizontalAlignment(JTextField.LEFT);
        //textField.setBounds(100, 100, 20, 20);         //在容器布局为空情况下生效
        textField.setPreferredSize(new Dimension(200,30));
        container.add(textField, BorderLayout.NORTH);

        String[] name= "7","8","9","+","4","5","6","-","1","2","3","*","0","C","=","/";

        panel.setLayout(new GridLayout(4,4,1,1));

        for (String s : name) 
            JButton button = new JButton(s);
            button.addActionListener(new MyActionListener());
            panel.add(button);
        
        container.add(panel,BorderLayout.CENTER);
    

    class MyActionListener implements ActionListener        //内部类实现按钮响应

        @Override
        public void actionPerformed(ActionEvent e) 
            int cnt=0;
            String actionCommand = e.getActionCommand();         //获取按钮上的字符串
            switch (actionCommand) 
                case "+":
                case "-":
                case "*":
                case "/":
                    input += " " + actionCommand + " ";
                    break;
                case "C":                    //清除输入
                    input = "";
                    break;
                case "=":                    //按下等号
                    try 
                        input += "=" + calculate(input);
                     catch (MyException e1) 
                        if (e1.getMessage().equals("Infinity"))
                            input += "=" + e1.getMessage();
                        else
                            input = e1.getMessage();
                    
                    textField.setText(input);
                    input = "";
                    cnt = 1;
                    break;
                default:
                    input += actionCommand;                            //按下数字
                    break;
            

            if(cnt == 0)
                textField.setText(input);
        
    

    private String calculate(String input) throws MyException          //计算函数
        String[] comput = input.split(" ");
        Stack<Double> stack = new Stack<>();
        Double m = Double.parseDouble(comput[0]);
        stack.push(m);                            //第一个操作数入栈

        for(int i = 1; i < comput.length; i++) 
            if(i%2==1) 
                if(comput[i].equals("+"))
                    stack.push(Double.parseDouble(comput[i+1]));
                if(comput[i].equals("-"))
                    stack.push(-Double.parseDouble(comput[i+1]));
                if(comput[i].equals("*"))                 //将前一个数出栈做乘法再入栈
                    Double d = stack.peek();            //取栈顶元素
                    stack.pop();
                    stack.push(d*Double.parseDouble(comput[i+1]));
                
                if(comput[i].equals("/"))                 //将前一个数出栈做乘法再入栈
                    double help = Double.parseDouble(comput[i+1]);
                    if(help == 0)
                        throw new MyException("Infinity");       //不会继续执行该函数
                    double d = stack.peek();
                    stack.pop();
                    stack.push(d/help);
                
            
        

        double d = 0d;

        while(!stack.isEmpty())         //求和
            d += stack.peek();
            stack.pop();
        

        return String.valueOf(d);
    

    public static void main(String[] args) 
        SwingConsole.run(new MyCalculator(), 250, 300);