用import java.awt.*设计一个简单计算器

以下是一个使用 Java AWT 设计的简单计算器的示例代码：

import java.awt.*;
import java.awt.event.*;

public class Calculator extends Frame implements ActionListener {

    private TextField resultField;

    private double operand1 = 0;
    private double operand2 = 0;
    private String operator = "";
    private boolean isOperatorSelected = false;

    public Calculator() {
        setTitle("Calculator");

        resultField = new TextField("0", 20);
        resultField.setEditable(false);

        Button btn1 = new Button("1");
        Button btn2 = new Button("2");
        Button btn3 = new Button("3");
        Button btn4 = new Button("4");
        Button btn5 = new Button("5");
        Button btn6 = new Button("6");
        Button btn7 = new Button("7");
        Button btn8 = new Button("8");
        Button btn9 = new Button("9");
        Button btn0 = new Button("0");
        Button btnPlus = new Button("+");
        Button btnMinus = new Button("-");
        Button btnMultiply = new Button("*");
        Button btnDivide = new Button("/");
        Button btnEquals = new Button("=");
        Button btnClear = new Button("C");

        btn1.addActionListener(this);
        btn2.addActionListener(this);
        btn3.addActionListener(this);
        btn4.addActionListener(this);
        btn5.addActionListener(this);
        btn6.addActionListener(this);
        btn7.addActionListener(this);
        btn8.addActionListener(this);
        btn9.addActionListener(this);
        btn0.addActionListener(this);
        btnPlus.addActionListener(this);
        btnMinus.addActionListener(this);
        btnMultiply.addActionListener(this);
        btnDivide.addActionListener(this);
        btnEquals.addActionListener(this);
        btnClear.addActionListener(this);

        Panel buttonPanel = new Panel(new GridLayout(4, 4, 5, 5));
        buttonPanel.add(btn1);
        buttonPanel.add(btn2);
        buttonPanel.add(btn3);
        buttonPanel.add(btnPlus);
        buttonPanel.add(btn4);
        buttonPanel.add(btn5);
        buttonPanel.add(btn6);
        buttonPanel.add(btnMinus);
        buttonPanel.add(btn7);
        buttonPanel.add(btn8);
        buttonPanel.add(btn9);
        buttonPanel.add(btnMultiply);
        buttonPanel.add(btnClear);
        buttonPanel.add(btn0);
        buttonPanel.add(btnEquals);
        buttonPanel.add(btnDivide);

        setLayout(new BorderLayout(5, 5));
        add(resultField, BorderLayout.NORTH);
        add(buttonPanel, BorderLayout.CENTER);

        pack();
        setVisible(true);
    }

    public void actionPerformed(ActionEvent e) {
        String buttonText = e.getActionCommand();
        switch (buttonText) {
            case "C":
                operand1 = 0;
                operand2 = 0;
                operator = "";
                isOperatorSelected = false;
                resultField.setText("0");
                break;
            case "+":
            case "-":
            case "*":
            case "/":
                if (isOperatorSelected) {
                    calculate();
                }
                operator = buttonText;
                operand1 = Double.parseDouble(resultField.getText());
                isOperatorSelected = true;
                break;
            case "=":
                if (isOperatorSelected) {
                    calculate();
                    isOperatorSelected = false;
                }
                break;
            default:
                if (isOperatorSelected) {
                    resultField.setText(buttonText);
                    operand2 = Double.parseDouble(buttonText);
                } else {
                    resultField.setText(resultField.getText() + buttonText);
                    operand1 = Double.parseDouble(resultField.getText());
                }
                break;
        }
    }

    private void calculate() {
        operand2 = Double.parseDouble(resultField.getText());
        switch (operator) {
            case "+":
                operand1 += operand2;
                break;
            case "-":
                operand1 -= operand2;
                break;
            case "*":
                operand1 *= operand2;
                break;
            case "/":
                operand1 /= operand2;
                break;
        }
        resultField.setText(Double.toString(operand1));
    }

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

该计算器界面包含一个文本框和一组按钮，用户可以通过点击按钮来输入数字和运算符，计算器支持加、减、乘、除四种基本运算，以及清除操作和等于操作。在用户输入数字和运算符的过程中，计算器会动态地更新文本框中的内容，用户点击等于操作后，计算器会根据之前的输入进行计算，并将计算结果显示在文本框中。