3

SimpleCalculator.java

@@ -45,4 +45,59 @@ public class SimpleCalculator extends JFrame {
         }
 
         add(panel, BorderLayout.CENTER);
+    }
+        private class ButtonClickListener implements ActionListener {
+            @Override
+            public void actionPerformed(ActionEvent e) {
+                String command = e.getActionCommand();
+
+                if ("0123456789.".contains(command)) {
+                    display.setText(display.getText().concat(command));
+                } else if ("+-*/".contains(command)) {
+                    operand1 = Double.parseDouble(display.getText());
+                    operator = command.charAt(0);
+                    userIsTypingSecondNumber = true;
+                    display.setText(""); // Clear the display for the next number
+                } else if (command.equals("=")) {
+                    if (userIsTypingSecondNumber) {
+                        operand2 = Double.parseDouble(display.getText());
+                        double result = 0;
+                        switch (operator) {
+                            case '+':
+                                result = operand1 + operand2;
+                                break;
+                            case '-':
+                                result = operand1 - operand2;
+                                break;
+                            case '*':
+                                result = operand1 * operand2;
+                                break;
+                            case '/':
+                                if (operand2 != 0) {
+                                    result = operand1 / operand2;
+                                } else {
+                                    display.setText("Error");
+                                    return;
+                                }
+                                break;
+                        }
+                        display.setText(String.valueOf(result));
+                        operand1 = result; // Store the result for possible chain operations
+                        userIsTypingSecondNumber = false; // Reset for next operation
+                    }
+                } else if (command.equals("C")) {
+                    display.setText("");
+                    operand1 = 0;
+                    operand2 = 0;
+                    userIsTypingSecondNumber = false;
+                }
+            }
+        }
+
+        public static void main(String[] args) {
+            SwingUtilities.invokeLater(() -> {
+                SimpleCalculator calculator = new SimpleCalculator();
+                calculator.setVisible(true);
+            });
+        }
     }