实现一个简单的计算器（JAVA代码详细注释）_java简易计算器代码及详细解释

如上图，实现一个计算器的+，-，*，/与重置的功能，具有异常处理功能

话不多说上代码：

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.text.NumberFormat;//保留小数
public class SimpleCalculation extends JFrame{
    Frame frame = new JFrame();
    Frame MistakeWindons = new JFrame();
    private JButton SumBtn = new JButton("SUM");
    private JButton SubBtn = new JButton("SUB");
    private JButton MulBtn = new JButton("MUL");
    private JButton DivBtn = new JButton("DIV");
    private JButton Reset = new JButton("Reset");

    private JTextField FristCount = new JTextField(5);
    private JTextField SecondCount = new JTextField(5);
    private JTextField Result = new JTextField(10);
    private Label Design = new Label("Design by 蒋永超");
    private Font Ft = new Font("宋体", Font.BOLD, 18);//设置字体
    public SimpleCalculation() {
        frame.setResizable(false);//设置为不可最大化
        frame.setTitle("简单计算器");
        frame.setLocation(600, 400);//设置窗口位置
        frame.setSize(300, 180);//设置窗口大小
        frame.setLayout(null);
        frame.setVisible(true);
        frame.add(FristCount);
        FristCount.setBounds(10, 10, 60, 20);
        frame.add(SecondCount);
        SecondCount.setBounds(90, 10, 60, 20);
        frame.add(new Label("=")).setBounds(160, 10, 20, 20);
        frame.add(Result);
        Result.setBounds(180, 10, 100, 20);
        frame.add(Design);
        Design.setBounds(60, 40, 200, 30);
        frame.add(SumBtn);
        SumBtn.setBounds(5, 80, 70, 30);
        frame.add(SubBtn);
        SubBtn.setBounds(75, 80, 70, 30);
        frame.add(MulBtn);
        MulBtn.setBounds(145, 80, 70, 30);
        frame.add(DivBtn);
        DivBtn.setBounds(215, 80, 70, 30);
        frame.add(Reset);
        Reset.setBounds(215,110,70,30);
        Design.setFont(Ft);
        MyActionListen();
    }
        private void MyActionListen(){//事件处理函数
        SumBtn.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                try {//异常处理，如果输入的不是数字，则提示输入错误
                    String text0 = FristCount.getText();//将JTextFiled转换String
                    String text1 = SecondCount.getText();
                    double a = Double.valueOf(text0);//将String类型转换为double
                    double b = Double.valueOf(text1);
                    Result.setText(a + b + "");
                }
                catch (Exception e1){
                    MistakeWindons.setResizable(false);
                    MistakeWindons.setLayout(null);
                    MistakeWindons.setTitle("Wrong Warning!");
                    MistakeWindons.setSize(200,100);
                    MistakeWindons.setLocation(550,550);
                    JLabel Mistake = new JLabel("Wrong Input!!!");
                    //Mistake.setFont(Ft);
                    Mistake.setBounds(50,20,100,20);
                    MistakeWindons.add(Mistake);
                    MistakeWindons.setVisible(true);
                }
                }
        });
            SubBtn.addActionListener(new ActionListener() {
                @Override
                public void actionPerformed(ActionEvent e) {
                    try {
                        String text0 = FristCount.getText();//将JTextFiled转换String
                        String text1 = SecondCount.getText();
                        double a = Double.valueOf(text0);//将String类型转换为double
                        double b = Double.valueOf(text1);
                        Result.setText(a - b + "");
                    }
                    catch (Exception e1){
                        MistakeWindons.setResizable(false);
                        MistakeWindons.setLayout(null);
                        MistakeWindons.setTitle("Wrong Warning!");
                        MistakeWindons.setSize(200,100);
                        MistakeWindons.setLocation(550,550);
                        JLabel Mistake = new JLabel("Wrong Input!!!");
                        //Mistake.setFont(Ft);
                        Mistake.setBounds(50,20,100,20);
                        MistakeWindons.add(Mistake);
                        MistakeWindons.setVisible(true);
                    }
                }
            });
            MulBtn.addActionListener(new ActionListener() {
                @Override
                public void actionPerformed(ActionEvent e) {
                    try {
                        String text0 = FristCount.getText();//将JTextFiled转换String
                        String text1 = SecondCount.getText();
                        double a = Double.valueOf(text0);//将String类型转换为double
                        double b = Double.valueOf(text1);
                        Result.setText(a * b + "");
                    }
                    catch (Exception e1){
                        MistakeWindons.setResizable(false);
                        MistakeWindons.setLayout(null);
                        MistakeWindons.setTitle("Wrong Warning!");
                        MistakeWindons.setSize(200,100);
                        MistakeWindons.setLocation(550,550);
                        JLabel Mistake = new JLabel("Wrong Input!!!");
                        Mistake.setBounds(50,20,100,20);
                        MistakeWindons.add(Mistake);
                        MistakeWindons.setVisible(true);
                    }
                }
            });
            DivBtn.addActionListener(new ActionListener() {
                @Override
                public void actionPerformed(ActionEvent e) {
                    try {
                        String text0 = FristCount.getText();//将JTextFiled转换String
                        String text1 = SecondCount.getText();
                        double a = Double.valueOf(text0);//将String类型转换为double
                        double b = Double.valueOf(text1);
                        Result.setText(a / b + "");
                        double c = a/b;
                        NumberFormat Nf = NumberFormat.getNumberInstance();//保留小数
                        Nf.setMaximumFractionDigits(6);
                        Result.setText(Nf.format(c));
                    }
                    catch (Exception e1){
                        MistakeWindons.setResizable(false);
                        MistakeWindons.setLayout(null);
                        MistakeWindons.setTitle("Wrong Warning!");
                        MistakeWindons.setSize(200,100);
                        MistakeWindons.setLocation(550,550);
                        JLabel Mistake = new JLabel("Wrong Input!!!");
                        //Mistake.setFont(Ft);
                        Mistake.setBounds(50,20,100,20);
                        MistakeWindons.add(Mistake);
                        MistakeWindons.setVisible(true);
                    }
                }
            });
        Reset.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                FristCount.setText("");
                SecondCount.setText("");
                Result.setText("");
            }
        });
    }
}
class Text{
    public static void main(String[] args){
        SimpleCalculation simpleCalculation = new SimpleCalculation();
    }
}

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有个问题没有考虑到，0不能做除数，
大家可以在DIV按钮下修改异常处理，把0不能做除数加进去就好。可以尝试自己去实现。