The document describes a Java program that uses a JPanel and event handling to merge two strings. When the user enters text into two text fields and clicks a button, the program concatenates the strings and displays the result in a third text field. The program creates a JPanel with labels and text fields, adds an action listener to the merge button, and defines a method to concatenate the strings from the first two fields and display it in the third field when the button is clicked.

2. Showing the use of Panel and Event handling in Java
The class Assign1 is accessing Jpanel class and using ActionListener
interface to handle the events.
/*
* Name:
*/
importjavax.swing.*;
importjava.awt.event.*;
importjava.awt.*;
public class Assign1 extends JPanel implements ActionListener {
privateJTextField field1;
privateJTextField field2;
privateJTextField field3;
privateJButtonmergeButton;
public Assign1() {
JPaneltopPanel = new JPanel();
// create the panel to have two text fields
// as the input and one text field as the output
// when the button is clicked, the two input texts
// are merged together and displayed in the output field
JLabel label1 = new JLabel("String 1: ");
JLabel label2 = new JLabel("String 2: ");
JLabel label3 = new JLabel("Result: ");
this.field1 = new JTextField();
this.field2 = new JTextField();
this.field3 = new JTextField();
this.mergeButton = new JButton("Merge Strings");
this.field3.setEditable(false);
topPanel.setLayout(new GridLayout(3, 2));
topPanel.add(label1);
topPanel.add(field1);
topPanel.add(label2);
topPanel.add(field2);
topPanel.add(label3);
topPanel.add(field3);
topPanel.setPreferredSize(new Dimension(400, 90));
this.setLayout(new BorderLayout());
this.add(topPanel, BorderLayout.CENTER);
this.add(mergeButton, BorderLayout.SOUTH);
// add button event listener
this.mergeButton.addActionListener(this);

3. }
@Override
public void actionPerformed(ActionEventae) {
// merge two strings in the input fields
String text1 = this.field1.getText().trim();
String text2 = this.field2.getText().trim();
StringBuilder result = new StringBuilder();
int i = 0;
while (i < text1.length() && i < text2.length()) {
// add one from each string
result.append(text1.charAt(i));
result.append(text2.charAt(i));
i ++;
}
// add the remaining part
if (i < text1.length()) {
result.append(text1.substring(i));
}
if (i < text2.length()) {
result.append(text2.substring(i));
}
// display the result
this.field3.setText(result.toString());
}
public static void main(String[] args) {
// create a JFrame to display the panel
JFrame frame = new JFrame();
frame.setContentPane(new Assign1());
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.pack();
frame.setVisible(true);
}
}