borderlayout计算器

以下是一个基于BorderLayout布局的计算器示例代码：

import java.awt.BorderLayout;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextField;

public class Calculator extends JFrame implements ActionListener {

    private static final long serialVersionUID = 1L;

    private JTextField text;
    private JButton zero, one, two, three, four, five, six, seven, eight, nine;
    private JButton add, subtract, multiply, divide, equals, clear;

    private double num1, num2;
    private String operator;

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

        // Set up the text field
        text = new JTextField();
        text.setEditable(false);

        // Set up the number buttons
        zero = new JButton("0");
        one = new JButton("1");
        two = new JButton("2");
        three = new JButton("3");
        four = new JButton("4");
        five = new JButton("5");
        six = new JButton("6");
        seven = new JButton("7");
        eight = new JButton("8");
        nine = new JButton("9");

        // Set up the operator buttons
        add = new JButton("+");
        subtract = new JButton("-");
        multiply = new JButton("*");
        divide = new JButton("/");
        equals = new JButton("=");
        clear = new JButton("C");

        // Add action listeners to all buttons
        zero.addActionListener(this);
        one.addActionListener(this);
        two.addActionListener(this);
        three.addActionListener(this);
        four.addActionListener(this);
        five.addActionListener(this);
        six.addActionListener(this);
        seven.addActionListener(this);
        eight.addActionListener(this);
        nine.addActionListener(this);
        add.addActionListener(this);
        subtract.addActionListener(this);
        multiply.addActionListener(this);
        divide.addActionListener(this);
        equals.addActionListener(this);
        clear.addActionListener(this);

        // Set up the button panel
        JPanel buttonPanel = new JPanel();
        buttonPanel.setLayout(new GridLayout(4, 4));
        buttonPanel.add(seven);
        buttonPanel.add(eight);
        buttonPanel.add(nine);
        buttonPanel.add(divide);
        buttonPanel.add(four);
        buttonPanel.add(five);
        buttonPanel.add(six);
        buttonPanel.add(multiply);
        buttonPanel.add(one);
        buttonPanel.add(two);
        buttonPanel.add(three);
        buttonPanel.add(subtract);
        buttonPanel.add(zero);
        buttonPanel.add(new JPanel());
        buttonPanel.add(equals);
        buttonPanel.add(add);

        // Add components to the frame using BorderLayout
        add(text, BorderLayout.NORTH);
        add(buttonPanel, BorderLayout.CENTER);
        add(clear, BorderLayout.SOUTH);

        // Set frame properties
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setSize(300, 300);
        setVisible(true);
    }

    public void actionPerformed(ActionEvent e) {
        // Get the button that was clicked
        JButton button = (JButton) e.getSource();

        // Handle number buttons
        if (button == zero) {
            text.setText(text.getText() + "0");
        } else if (button == one) {
            text.setText(text.getText() + "1");
        } else if (button == two) {
            text.setText(text.getText() + "2");
        } else if (button == three) {
            text.setText(text.getText() + "3");
        } else if (button == four) {
            text.setText(text.getText() + "4");
        } else if (button == five) {
            text.setText(text.getText() + "5");
        } else if (button == six) {
            text.setText(text.getText() + "6");
        } else if (button == seven) {
            text.setText(text.getText() + "7");
        } else if (button == eight) {
            text.setText(text.getText() + "8");
        } else if (button == nine) {
            text.setText(text.getText() + "9");
        }
        // Handle operator buttons
        else if (button == add) {
            num1 = Double.parseDouble(text.getText());
            operator = "+";
            text.setText("");
        } else if (button == subtract) {
            num1 = Double.parseDouble(text.getText());
            operator = "-";
            text.setText("");
        } else if (button == multiply) {
            num1 = Double.parseDouble(text.getText());
            operator = "*";
            text.setText("");
        } else if (button == divide) {
            num1 = Double.parseDouble(text.getText());
            operator = "/";
            text.setText("");
        } else if (button == equals) {
            num2 = Double.parseDouble(text.getText());
            if (operator.equals("+")) {
                text.setText("" + (num1 + num2));
            } else if (operator.equals("-")) {
                text.setText("" + (num1 - num2));
            } else if (operator.equals("*")) {
                text.setText("" + (num1 * num2));
            } else if (operator.equals("/")) {
                if (num2 == 0) {
                    text.setText("Error");
                } else {
                    text.setText("" + (num1 / num2));
                }
            }
        } else if (button == clear) {
            text.setText("");
        }
    }

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

这个计算器使用BorderLayout布局，将文本框放在北部，按钮面板放在中间，清除按钮放在南部。按钮面板使用GridLayout布局，以4行4列显示数字和操作符按钮。每个按钮都添加了一个ActionListener，以便在单击时执行相应的操作。这个计算器可以处理加法、减法、乘法和除法运算，以及清除当前输入和显示结果。