Java计算器

99行代码 

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

public class Calculator extends JFrame {
    private String[] labels = { "%","√","x²","1/x","CE","C","←","÷",
        "7","8","9","×","4","5","6","-","1","2","3","+","±","0",".","=" };
    private String a = "", b = "", op = "";
    JPanel panel;
    JTextField comp;

    public Calculator() {
        setLayout(new BorderLayout());
        Font font = new Font("Sanserif", Font.BOLD, 25);
        comp = new JTextField("0");
        comp.setHorizontalAlignment(JTextField.RIGHT);
        comp.setBounds(10, 8, 271, 50);
        comp.setFont(font);
        panel = new JPanel();
        panel.setLayout(null);
        panel.add(comp);
        for (int i = 0; i < 24; i++) {
            JButton button = new JButton(labels[i]);
            if (labels[i].length() == 1 && labels[i].charAt(0) >= '0'
                && labels[i].charAt(0) <= '9' || labels[i] == ".") {
                button.addActionListener(new InsertAction());
                button.setFont(font);
            }
            else button.addActionListener(new CommandAction());
            int x = i % 4 * 70 + 10, y = i / 4 * 48 + 70;
            button.setLayout(null);
            button.setBounds(x, y, 60, 40);
            panel.add(button);
        }
        add(panel, BorderLayout.CENTER);
    }
    private class InsertAction implements ActionListener {
        public void actionPerformed(ActionEvent e) {
            String s = e.getActionCommand();
            if (s != "." || b.indexOf(".") == -1) b += s;
            comp.setText(b);
        }
    }
    private class CommandAction implements ActionListener {
        public void actionPerformed(ActionEvent e) {
            String s = e.getActionCommand();
            if (s == "+" || s == "-" || s == "×" || s == "÷") {
                a = b; b = ""; op = s;
                comp.setText(s);
            }
            else if (s == "=") {
                double A = Double.parseDouble(a);
                double B = Double.parseDouble(b);
                switch (op) {
                case "+":A += B; break;
                case "-":A -= B; break;
                case "×":A *= B; break;
                case "÷":A /= B; break;
                }
                long C = Math.round(A);
                a = b = Math.abs(C - A) < 1e-12 ? C + "" : A + "";
                comp.setText(b);
            }
            else if (s == "±" || s == "√" || s == "x²" || s == "1/x") {
                double B = Double.parseDouble(b);
                switch (s) {
                case "±":B = -B; break;
                case "√":B = Math.sqrt(B); break;
                case "x²":B *= B; break;
                case "1/x":B = 1 / B; break;
                }
                long C = Math.round(B);
                b = Math.abs(C - B) < 1e-12 ? C + "" : B + "";
                comp.setText(b);
            }
            else if (s == "←") {
                if (b.length() != 0) {
                    b = b.substring(0, b.length() - 1);
                    comp.setText(b);
                }
            }
            else if (s.charAt(0) == 'C') {
                a = b = op = "";
                comp.setText("0");
            }
        }
    }
    public static void main(String[] args) {
        EventQueue.invokeLater(()-> {
            JFrame frame = new Calculator();
            frame.setTitle("Calculator");
            frame.setResizable(false);
            frame.setLocationRelativeTo(null);
            frame.setSize(297, 390);
            frame.setVisible(true);
            frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        });
    }
}

　　

效果图

按键顺序参照Win10计算器：

ps：除了%不知道有啥用，还有CE和C的功能写的一样之外，其他都实现了

暂时还没有发现逻辑错误