Java实现简易计算器

需求：实现加减乘除的运算。

实现代码：

Const类（常量类）：

package gui.carculator;

import java.awt.*;


public class Const {
    //设置窗体大小
    public static final int FRAME_W = 400;
    public static final int FRAME_H = 400;

    //得到窗体的宽度,得到窗体的高度
    public static final int SCREEN_W = Toolkit.getDefaultToolkit().getScreenSize().width;
    public static final int SCREEN_H = Toolkit.getDefaultToolkit().getScreenSize().height;

    //得到中心点位置
    public static final int FRAME_X = (SCREEN_W - FRAME_W) / 2;
    public static final int FRAME_Y = (SCREEN_H - FRAME_H) / 2;
}

Curculator类（计算器类）： 

package gui.carculator;

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


public class Curculator extends JFrame implements ActionListener {

    //北面控件
    private JPanel jp_north = new JPanel();//设置面板
    private JTextField input_text = new JTextField();//文本框
    private JButton c_Btn = new JButton("清空");//按钮

    //中间的控件
    private JPanel jp_center = new JPanel();//设置面板


    public Curculator() throws HeadlessException {
        this.init();
        this.addNorthComponent();
        this.addCenterButton();
    }

    
    public void init() {
        //窗体名称
        this.setTitle("通通计算器");
        //窗体大小
        this.setSize(Const.FRAME_W, Const.FRAME_H);
        //设置窗体不可拉长
        this.setResizable(false);
        this.setLayout(new BorderLayout());
        //设置窗体显示在中心点
        this.setLocation(Const.FRAME_X, Const.FRAME_Y);
        //设置点叉关闭
        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    }

    
    public void addNorthComponent() {
        //设置文本框的大小
        this.input_text.setPreferredSize(new Dimension(300, 30));

        jp_north.add(input_text);

        //设置按钮颜色
        c_Btn.setForeground(Color.RED);
        jp_north.add(c_Btn);
        //点击此按钮后将文本框内容清空
        c_Btn.addActionListener((e) -> {
            input_text.setText("");
        });

        //将面板加入到窗体的北面
        this.add(jp_north, BorderLayout.NORTH);
    }

    
    public void addCenterButton() {
        String btn_text = "123+456-789*0.=/";
        String regex = "[\+\-*/.=]";
        this.jp_center.setLayout(new GridLayout(4, 4));
        for (int i = 0; i < 16; i++) {
            String temp = btn_text.substring(i, i + 1);
            JButton btn = new JButton();
            btn.setText(temp);
            //正则表达式写法
            if (temp.matches(regex)) {
                btn.setFont(new Font("粗体", Font.BOLD, 20));
                btn.setForeground(Color.RED);
            }

//            if (temp.equals("+")||temp.equals("-")||temp.equals("*")||temp.equals("/")||temp.equals(".")||temp.equals("=")){
//                btn.setFont(new Font("粗体",Font.BOLD,20));
//                btn.setForeground(Color.RED);
//            }

            //事件监听
            btn.addActionListener(this);
            jp_center.add(btn);
        }
        this.add(jp_center, BorderLayout.CENTER);
    }

    
    private String firstInput = null;
    private String operator = null;

    @Override
    public void actionPerformed(ActionEvent e) {
        String clickStr = e.getActionCommand();
        if (".0123456789".indexOf(clickStr) != -1) {
            //获取的数字显示在文本框
            this.input_text.setText(input_text.getText() + clickStr);
            this.input_text.setHorizontalAlignment(JTextField.RIGHT);
            //显示在弹窗
//            JOptionPane.showMessageDialog(this,clickStr);
        } else if (clickStr.matches("[\+\-*/]{1}")) {
            operator = clickStr;
            firstInput = this.input_text.getText();
            this.input_text.setText("");
        } else if (clickStr.equals("=")) {
            Double a = Double.valueOf(firstInput);
            Double b = Double.valueOf(this.input_text.getText());
            Double result = null;
            switch (operator) {
                case "+":
                    result = a + b;
                    break;
                case "-":
                    result = a - b;
                    break;
                case "*":
                    result = a * b;
                    break;
                case "/":

                    if (b != 0) {
                        result = a / b;
                    } else {
                        JOptionPane.showMessageDialog(this,new String("输入错误，除数不能为0！！！"));
                    }
                    break;
                default:
                    break;
            }
            this.input_text.setText(result.toString());
        }
    }
}

Test类（实现类）：

package gui.carculator;

public class Test {
    public static void main(String[] args) {

        Curculator curculator=new Curculator();
        curculator.setVisible(true);
    }
}