写一个可以进行简单计算的计算器界面的java代码

以下是一个简单的计算器界面的Java代码示例：

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

public class Calculator extends JFrame implements ActionListener {
    private JTextField display;
    private JButton buttons[];

    private String operator = "";
    private double result = 0;

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

        display = new JTextField(20);
        display.setEditable(false);
        display.setHorizontalAlignment(JTextField.RIGHT);

        JPanel panel = new JPanel();
        panel.setLayout(new GridLayout(4, 4, 5, 5));

        buttons = new JButton[16];
        for (int i = 0; i < buttons.length; i++) {
            buttons[i] = new JButton();
            buttons[i].addActionListener(this);
            panel.add(buttons[i]);
        }

        buttons[0].setText("7");
        buttons[1].setText("8");
        buttons[2].setText("9");
        buttons[3].setText("/");
        buttons[4].setText("4");
        buttons[5].setText("5");
        buttons[6].setText("6");
        buttons[7].setText("*");
        buttons[8].setText("1");
        buttons[9].setText("2");
        buttons[10].setText("3");
        buttons[11].setText("-");
        buttons[12].setText("0");
        buttons[13].setText(".");
        buttons[14].setText("=");
        buttons[15].setText("+");

        JPanel contentPane = new JPanel();
        contentPane.setLayout(new BorderLayout());
        contentPane.add(display, BorderLayout.NORTH);
        contentPane.add(panel, BorderLayout.CENTER);

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

    public void actionPerformed(ActionEvent e) {
        if (e.getSource() == buttons[0]) {
            display.setText(display.getText() + "7");
        } else if (e.getSource() == buttons[1]) {
            display.setText(display.getText() + "8");
        } else if (e.getSource() == buttons[2]) {
            display.setText(display.getText() + "9");
        } else if (e.getSource() == buttons[3]) {
            operator = "/";
            result = Double.parseDouble(display.getText());
            display.setText("");
        } else if (e.getSource() == buttons[4]) {
            display.setText(display.getText() + "4");
        } else if (e.getSource() == buttons[5]) {
            display.setText(display.getText() + "5");
        } else if (e.getSource() == buttons[6]) {
            display.setText(display.getText() + "6");
        } else if (e.getSource() == buttons[7]) {
            operator = "*";
            result = Double.parseDouble(display.getText());
            display.setText("");
        } else if (e.getSource() == buttons[8]) {
            display.setText(display.getText() + "1");
        } else if (e.getSource() == buttons[9]) {
            display.setText(display.getText() + "2");
        } else if (e.getSource() == buttons[10]) {
            display.setText(display.getText() + "3");
        } else if (e.getSource() == buttons[11]) {
            operator = "-";
            result = Double.parseDouble(display.getText());
            display.setText("");
        } else if (e.getSource() == buttons[12]) {
            display.setText(display.getText() + "0");
        } else if (e.getSource() == buttons[13]) {
            display.setText(display.getText() + ".");
        } else if (e.getSource() == buttons[14]) {
            if (operator.equals("+")) {
                result += Double.parseDouble(display.getText());
            } else if (operator.equals("-")) {
                result -= Double.parseDouble(display.getText());
            } else if (operator.equals("*")) {
                result *= Double.parseDouble(display.getText());
            } else if (operator.equals("/")) {
                result /= Double.parseDouble(display.getText());
            } else {
                result = Double.parseDouble(display.getText());
            }
            display.setText("" + result);
            operator = "";
        } else if (e.getSource() == buttons[15]) {
            operator = "+";
            result = Double.parseDouble(display.getText());
            display.setText("");
        }
    }

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

这个示例代码使用了JFrame和JPanel类来创建基本的计算器界面，使用了GridLayout布局将按钮放置在一个4x4的网格中。每个按钮都有一个ActionListener，点击时会执行相应的操作。在操作过程中，每个数字都会显示在JTextField中，而每个操作符和结果都存储在相应的变量中。最后，点击“=”按钮时，将执行所选的操作并在JTextField中显示结果。