第一次

jisuanji/Calculator.java

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+package jisuanji;
+public class Calculator {
+    // 加法
+    public double add(double a, double b) {
+        return a + b;
+    }
+
+    // 减法
+    public double subtract(double a, double b) {
+        return a - b;
+    }
+
+    // 乘法
+    public double multiply(double a, double b) {
+        return a * b;
+    }
+
+    // 除法
+    public double divide(double a, double b) {
+        if (b != 0) {
+            return a / b;
+        } else {
+            throw new IllegalArgumentException("除数不能为零");
+        }
+    }
+
+    // 取余
+    public double modulus(double a, double b) {
+        return a % b;
+    }
+}

jisuanji/CalculatorGUI.java

@@ -0,0 +1,92 @@
+package jisuanji;
+
+import javax.swing.*;
+import java.awt.*;
+import java.awt.event.ActionEvent;
+import java.awt.event.ActionListener;
+
+public class CalculatorGUI extends JFrame {
+    private JTextField display;
+    private Calculator calculator = new Calculator();
+    private double firstNumber = 0;
+    private double secondNumber = 0;
+    private String operation = "";
+    private boolean isOperationClicked = false;
+
+    public CalculatorGUI() {
+        setTitle("简易计算器");
+        setSize(400, 600);
+        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
+        setLocationRelativeTo(null);
+
+        display = new JTextField();
+        display.setEditable(false);
+        display.setFont(new Font("Arial", Font.PLAIN, 40));
+        display.setHorizontalAlignment(JTextField.RIGHT);
+        display.setBorder(BorderFactory.createLineBorder(Color.BLACK));
+
+        JPanel panel = new JPanel();
+        panel.setLayout(new GridLayout(4, 4, 10, 10));
+
+        String[] buttons = {
+                "7", "8", "9", "/",
+                "4", "5", "6", "*",
+                "1", "2", "3", "-",
+                "0", ".", "=", "+"
+        };
+
+        for (String buttonText : buttons) {
+            JButton button = new JButton(buttonText);
+            button.setFont(new Font("Arial", Font.PLAIN, 24));
+            button.addActionListener(new ButtonClickListener());
+            panel.add(button);
+        }
+
+        add(display, BorderLayout.NORTH);
+        add(panel, BorderLayout.CENTER);
+
+        setVisible(true);
+    }
+
+    private class ButtonClickListener implements ActionListener {
+        @Override
+        public void actionPerformed(ActionEvent e) {
+            String command = e.getActionCommand();
+
+            if ("0123456789.".indexOf(command) >= 0) {
+                display.setText(display.getText() + command);
+                isOperationClicked = false;
+            } else if ("+*/-=".indexOf(command) >= 0) {
+                if (!isOperationClicked) {
+                    firstNumber = Double.parseDouble(display.getText());
+                    operation = command;
+                    isOperationClicked = true;
+                    display.setText("");
+                } else if (command.equals("=")) {
+                    secondNumber = Double.parseDouble(display.getText());
+                    double result = 0;
+                    switch (operation) {
+                        case "+":
+                            result = calculator.add(firstNumber, secondNumber);
+                            break;
+                        case "-":
+                            result = calculator.subtract(firstNumber, secondNumber);
+                            break;
+                        case "*":
+                            result = calculator.multiply(firstNumber, secondNumber);
+                            break;
+                        case "/":
+                            result = calculator.divide(firstNumber, secondNumber);
+                            break;
+                    }
+                    display.setText(String.valueOf(result));
+                    isOperationClicked = false;
+                }
+            }
+        }
+    }
+
+    public static void main(String[] args) {
+        new CalculatorGUI();
+    }
+}