练习swing布局和事件布局中计算器的界面和简单功能

好的，我可以帮你实现一个基于Swing的简单计算器界面和功能。下面是实现步骤：

1. 创建一个基于JFrame的窗口，并设置窗口标题和大小。

import javax.swing.*;

public class Calculator extends JFrame {

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

    public Calculator() {
        setTitle("Calculator");
        setSize(300, 400);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setVisible(true);
    }
}

2. 在窗口中创建一个JPanel，并使用GridLayout布局，将JPanel分为5行4列，每个单元格大小相等。

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

public class Calculator extends JFrame {

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

    public Calculator() {
        setTitle("Calculator");
        setSize(300, 400);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        JPanel panel = new JPanel(new GridLayout(5, 4));
        add(panel);

        setVisible(true);
    }
}

3. 在JPanel中添加JButton，并设置文本和字体。

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

public class Calculator extends JFrame {

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

    public Calculator() {
        setTitle("Calculator");
        setSize(300, 400);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        JPanel panel = new JPanel(new GridLayout(5, 4));
        add(panel);

        JButton button1 = new JButton("7");
        button1.setFont(new Font("Arial", Font.PLAIN, 20));
        panel.add(button1);

        JButton button2 = new JButton("8");
        button2.setFont(new Font("Arial", Font.PLAIN, 20));
        panel.add(button2);

        // 添加其它按钮

        setVisible(true);
    }
}

4. 使用BorderLayout布局，在窗口底部添加一个JTextField，用于显示计算结果。

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

public class Calculator extends JFrame {

    private JTextField resultField = new JTextField();

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

    public Calculator() {
        setTitle("Calculator");
        setSize(300, 400);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        JPanel panel = new JPanel(new GridLayout(5, 4));
        add(panel, BorderLayout.CENTER);

        JButton button1 = new JButton("7");
        button1.setFont(new Font("Arial", Font.PLAIN, 20));
        panel.add(button1);

        JButton button2 = new JButton("8");
        button2.setFont(new Font("Arial", Font.PLAIN, 20));
        panel.add(button2);

        // 添加其它按钮

        add(resultField, BorderLayout.SOUTH);

        setVisible(true);
    }
}

5. 添加事件监听器，实现计算器的功能。这里仅实现加法功能。可以在每个按钮上添加相应的ActionListener，也可以使用一个统一的ActionListener。

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

public class Calculator extends JFrame {

    private JTextField resultField = new JTextField();

    private double num1 = 0;
    private double num2 = 0;
    private String operator = "+";

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

    public Calculator() {
        setTitle("Calculator");
        setSize(300, 400);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        JPanel panel = new JPanel(new GridLayout(5, 4));
        add(panel, BorderLayout.CENTER);

        JButton button1 = new JButton("7");
        button1.setFont(new Font("Arial", Font.PLAIN, 20));
        button1.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                resultField.setText(resultField.getText() + "7");
            }
        });
        panel.add(button1);

        JButton button2 = new JButton("8");
        button2.setFont(new Font("Arial", Font.PLAIN, 20));
        button2.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                resultField.setText(resultField.getText() + "8");
            }
        });
        panel.add(button2);

        JButton addButton = new JButton("+");
        addButton.setFont(new Font("Arial", Font.PLAIN, 20));
        addButton.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                num1 = Double.parseDouble(resultField.getText());
                operator = "+";
                resultField.setText("");
            }
        });
        panel.add(addButton);

        JButton calculateButton = new JButton("=");
        calculateButton.setFont(new Font("Arial", Font.PLAIN, 20));
        calculateButton.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                num2 = Double.parseDouble(resultField.getText());
                switch (operator) {
                    case "+":
                        resultField.setText(String.valueOf(num1 + num2));
                        break;
                }
            }
        });
        panel.add(calculateButton);

        add(resultField, BorderLayout.SOUTH);

        setVisible(true);
    }
}

这样，一个简单的计算器界面和加法功能就实现了。你可以根据需要添加其它功能，例如减法、乘法、除法等。