calculator

package javalab;

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

public class Sample {
    public static void main(String[] args) {
        // Create a new JFrame with a title
        JFrame f = new JFrame("Calculator");
        f.setSize(500, 400);
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.setLayout(null);

        // Label for instruction
        JLabel l = new JLabel("Enter the string:");
        l.setBounds(100, 100, 150, 25);
        f.add(l);

        // Text field to input the string
        JTextField t = new JTextField(20);
        t.setBounds(250, 100, 150, 25);
        f.add(t);

        // Label to display the reversed string
        JLabel l2 = new JLabel("");
        l2.setBounds(150, 200, 300, 25);
        f.add(l2);

        // Button to trigger the reversal
        JButton b = new JButton("Reverse");
        b.setBounds(200, 150, 100, 25);
        f.add(b);

        // Action listener for the button
        b.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                // Get text from the text field
                String s = t.getText();
                
                // Reverse the string without using inbuilt functions
                String s1 = "";
                for (int i = s.length() - 1; i >= 0; i--) {
                    s1 += s.charAt(i);
                }
                
                // Set the reversed string in the label
                l2.setText("Reversed string: " + s1);
            }
        });

        // Make the frame visible
        f.setVisible(true);
    }
}