Java简易计算器界面以及功能设计

下面是一个简单的Java计算器程序，具有基本的计算功能和一个简单的图形用户界面：

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

public class Calculator extends JFrame implements ActionListener {
    private JTextField display;
    private JButton clear, add, subtract, multiply, divide, equals;
    private JButton[] digits;
    private double currentNumber = 0;
    private String currentOperation = "";
    
    public Calculator() {
        super("Calculator");
        setSize(200, 200);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        
        JPanel panel1 = new JPanel(new FlowLayout());
        display = new JTextField(10);
        panel1.add(display);
        
        JPanel panel2 = new JPanel(new GridLayout(4, 3));
        digits = new JButton[10];
        for (int i = 0; i < 10; i++) {
            digits[i] = new JButton("" + i);
            digits[i].addActionListener(this);
            panel2.add(digits[i]);
        }
        
        clear = new JButton("C");
        clear.addActionListener(this);
        panel2.add(clear);
        
        add = new JButton("+");
        add.addActionListener(this);
        panel2.add(add);
        
        subtract = new JButton("-");
        subtract.addActionListener(this);
        panel2.add(subtract);
        
        multiply = new JButton("*");
        multiply.addActionListener(this);
        panel2.add(multiply);
        
        divide = new JButton("/");
        divide.addActionListener(this);
        panel2.add(divide);
        
        equals = new JButton("=");
        equals.addActionListener(this);
        panel2.add(equals);
        
        setLayout(new BorderLayout());
        add(panel1, BorderLayout.NORTH);
        add(panel2, BorderLayout.CENTER);
    }
    
    public void actionPerformed(ActionEvent e) {
        String action = e.getActionCommand();
        if (action.equals("C")) {
            currentNumber = 0;
            display.setText("");
        } else if (action.equals("+")) {
            currentOperation = "+";
            currentNumber = Double.parseDouble(display.getText());
            display.setText("");
        } else if (action.equals("-")) {
            currentOperation = "-";
            currentNumber = Double.parseDouble(display.getText());
            display.setText("");
        } else if (action.equals("*")) {
            currentOperation = "*";
            currentNumber = Double.parseDouble(display.getText());
            display.setText("");
        } else if (action.equals("/")) {
            currentOperation = "/";
            currentNumber = Double.parseDouble(display.getText());
            display.setText("");
        } else if (action.equals("=")) {
            double secondNumber = Double.parseDouble(display.getText());
            double result = 0;
            if (currentOperation.equals("+")) {
                result = currentNumber + secondNumber;
            } else if (currentOperation.equals("-")) {
                result = currentNumber - secondNumber;
            } else if (currentOperation.equals("*")) {
                result = currentNumber * secondNumber;
            } else if (currentOperation.equals("/")) {
                result = currentNumber / secondNumber;
            }
            currentNumber = result;
            display.setText("" + result);
        } else {
            display.setText(display.getText() + action);
        }
    }
    
    public static void main(String[] args) {
        Calculator calculator = new Calculator();
        calculator.setVisible(true);
    }
}

该程序使用JFrame和JPanel创建了一个简单的图形用户界面。JPanel使用GridLayout来放置数字和操作按钮，而JTextField用于显示当前计算结果。

当用户按下数字按钮时，该数字将显示在JTextField中。当用户按下操作按钮时，程序将保存当前数字并等待下一个数字。当用户按下等号按钮时，程序将计算结果并在JTextField中显示。

该程序非常简单，但它可以帮助您了解如何以编程方式创建基本的图形用户界面，并使用Java进行简单的数学计算。