java
import javax.swing.*;

public class RectangleCalculator {
    public static void main(String[] args) {
        // Create a JFrame
        JFrame frame = new JFrame("Rectangle Calculator");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        
        // Create a JPanel for the content
        JPanel panel = new JPanel();
        
        // Create JLabels and JTextFields
        JLabel lengthLabel = new JLabel("Enter the length:");
        JTextField lengthTextField = new JTextField(10);
        
        JLabel widthLabel = new JLabel("Enter the width:");
        JTextField widthTextField = new JTextField(10);
        
        JLabel areaLabel = new JLabel("Area: ");
        JLabel perimeterLabel = new JLabel("Perimeter: ");
        
        JButton calculateButton = new JButton("Calculate");
        
        // Add action listener to the calculate button
        calculateButton.addActionListener(e -> {
            // Get the values entered by the user
            double length = Double.parseDouble(lengthTextField.getText());
            double width = Double.parseDouble(widthTextField.getText());
            
            // Calculate the area and perimeter
            double area = length * width;
            double perimeter = 2 * (length + width);
            
            // Update the labels with the calculated values
            areaLabel.setText("Area: " + area);
            perimeterLabel.setText("Perimeter: " + perimeter);
        });
        
        // Create an Exit button
        JButton exitButton = new JButton("Exit");
        
        // Add action listener to the exit button
        exitButton.addActionListener(e -> System.exit(0));

        // Add components to the panel
        panel.add(lengthLabel);
        panel.add(lengthTextField);
        
        panel.add(widthLabel);
        panel.add(widthTextField);
        
        panel.add(calculateButton);
        panel.add(areaLabel);
        panel.add(perimeterLabel);
        
        panel.add(exitButton);
        
        // Add panel to the frame
        frame.getContentPane().add(panel);
        
        // Set the frame size and make it visible
        frame.setSize(300, 200);
        frame.setVisible(true);
    }
}