用Java编写一个具备加减乘除的计算器界面代码

以下是使用Java Swing编写的简单计算器界面代码，实现了加减乘除四则运算：

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

public class Calculator extends JFrame implements ActionListener {

    private JButton button0, button1, button2, button3, button4, button5, button6, button7, button8, button9;
    private JButton buttonAdd, buttonSubtract, buttonMultiply, buttonDivide, buttonClear, buttonEquals;
    private JTextField textField;

    private double firstValue = 0;
    private double secondValue = 0;
    private String operation = "";

    public Calculator() {
        super("Calculator");

        // Set up the text field
        textField = new JTextField(10);
        textField.setEditable(false);
        textField.setHorizontalAlignment(JTextField.RIGHT);

        // Set up the buttons
        button0 = new JButton("0");
        button1 = new JButton("1");
        button2 = new JButton("2");
        button3 = new JButton("3");
        button4 = new JButton("4");
        button5 = new JButton("5");
        button6 = new JButton("6");
        button7 = new JButton("7");
        button8 = new JButton("8");
        button9 = new JButton("9");
        buttonAdd = new JButton("+");
        buttonSubtract = new JButton("-");
        buttonMultiply = new JButton("*");
        buttonDivide = new JButton("/");
        buttonClear = new JButton("C");
        buttonEquals = new JButton("=");

        button0.addActionListener(this);
        button1.addActionListener(this);
        button2.addActionListener(this);
        button3.addActionListener(this);
        button4.addActionListener(this);
        button5.addActionListener(this);
        button6.addActionListener(this);
        button7.addActionListener(this);
        button8.addActionListener(this);
        button9.addActionListener(this);
        buttonAdd.addActionListener(this);
        buttonSubtract.addActionListener(this);
        buttonMultiply.addActionListener(this);
        buttonDivide.addActionListener(this);
        buttonClear.addActionListener(this);
        buttonEquals.addActionListener(this);

        // Set up the content pane
        JPanel contentPane = new JPanel();
        contentPane.setLayout(new BorderLayout());
        contentPane.setBorder(BorderFactory.createEmptyBorder(10, 10, 10, 10));

        JPanel buttonPanel = new JPanel();
        buttonPanel.setLayout(new GridLayout(4, 4, 5, 5));
        buttonPanel.add(button7);
        buttonPanel.add(button8);
        buttonPanel.add(button9);
        buttonPanel.add(buttonDivide);
        buttonPanel.add(button4);
        buttonPanel.add(button5);
        buttonPanel.add(button6);
        buttonPanel.add(buttonMultiply);
        buttonPanel.add(button1);
        buttonPanel.add(button2);
        buttonPanel.add(button3);
        buttonPanel.add(buttonSubtract);
        buttonPanel.add(button0);
        buttonPanel.add(buttonClear);
        buttonPanel.add(buttonEquals);
        buttonPanel.add(buttonAdd);

        contentPane.add(textField, BorderLayout.NORTH);
        contentPane.add(buttonPanel, BorderLayout.CENTER);

        setContentPane(contentPane);
        pack();
        setLocationRelativeTo(null);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setResizable(false);
    }

    public void actionPerformed(ActionEvent e) {
        if (e.getSource() == button0) {
            textField.setText(textField.getText() + "0");
        } else if (e.getSource() == button1) {
            textField.setText(textField.getText() + "1");
        } else if (e.getSource() == button2) {
            textField.setText(textField.getText() + "2");
        } else if (e.getSource() == button3) {
            textField.setText(textField.getText() + "3");
        } else if (e.getSource() == button4) {
            textField.setText(textField.getText() + "4");
        } else if (e.getSource() == button5) {
            textField.setText(textField.getText() + "5");
        } else if (e.getSource() == button6) {
            textField.setText(textField.getText() + "6");
        } else if (e.getSource() == button7) {
            textField.setText(textField.getText() + "7");
        } else if (e.getSource() == button8) {
            textField.setText(textField.getText() + "8");
        } else if (e.getSource() == button9) {
            textField.setText(textField.getText() + "9");
        } else if (e.getSource() == buttonAdd) {
            firstValue = Double.parseDouble(textField.getText());
            operation = "+";
            textField.setText("");
        } else if (e.getSource() == buttonSubtract) {
            firstValue = Double.parseDouble(textField.getText());
            operation = "-";
            textField.setText("");
        } else if (e.getSource() == buttonMultiply) {
            firstValue = Double.parseDouble(textField.getText());
            operation = "*";
            textField.setText("");
        } else if (e.getSource() == buttonDivide) {
            firstValue = Double.parseDouble(textField.getText());
            operation = "/";
            textField.setText("");
        } else if (e.getSource() == buttonClear) {
            textField.setText("");
        } else if (e.getSource() == buttonEquals) {
            secondValue = Double.parseDouble(textField.getText());
            double result = 0;
            if (operation.equals("+")) {
                result = firstValue + secondValue;
            } else if (operation.equals("-")) {
                result = firstValue - secondValue;
            } else if (operation.equals("*")) {
                result = firstValue * secondValue;
            } else if (operation.equals("/")) {
                result = firstValue / secondValue;
            }
            textField.setText(Double.toString(result));
        }
    }

    public static void main(String[] args) {
        Calculator calculator = new Calculator();
        calculator.setVisible(true);
    }

}