GroupLayout is a layout manager in Java that allows you to create complex layouts by grouping components together and specifying how they should be aligned and sized relative to each other. GroupLayout was introduced in Java 6 and is typically used in Swing applications.

Here's an example of how to use GroupLayout to create a simple login form with two text fields and a login button:

import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JTextField;
import javax.swing.JButton;
import javax.swing.GroupLayout;

public class GroupLayoutExample {
    public static void main(String[] args) {
        JFrame frame = new JFrame("GroupLayout Example");

        JLabel usernameLabel = new JLabel("Username:");
        JTextField usernameField = new JTextField();
        JLabel passwordLabel = new JLabel("Password:");
        JTextField passwordField = new JTextField();
        JButton loginButton = new JButton("Login");

        GroupLayout layout = new GroupLayout(frame.getContentPane());
        frame.getContentPane().setLayout(layout);
        layout.setAutoCreateGaps(true);
        layout.setAutoCreateContainerGaps(true);

        layout.setHorizontalGroup(layout.createSequentialGroup()
                .addGroup(layout.createParallelGroup(GroupLayout.Alignment.LEADING)
                        .addComponent(usernameLabel)
                        .addComponent(passwordLabel))
                .addGroup(layout.createParallelGroup(GroupLayout.Alignment.LEADING)
                        .addComponent(usernameField)
                        .addComponent(passwordField)
                        .addComponent(loginButton)));

        layout.setVerticalGroup(layout.createSequentialGroup()
                .addGroup(layout.createParallelGroup(GroupLayout.Alignment.BASELINE)
                        .addComponent(usernameLabel)
                        .addComponent(usernameField))
                .addGroup(layout.createParallelGroup(GroupLayout.Alignment.BASELINE)
                        .addComponent(passwordLabel)
                        .addComponent(passwordField))
                .addComponent(loginButton));

        frame.pack();
        frame.setVisible(true);
    }
}

In this example, we create a new JFrame and add a JLabel for the username, a JTextField for the username input, a JLabel for the password, a JTextField for the password input, and a JButton for the login action.

We then create a new GroupLayout and set it as the layout manager for the JFrame's content pane. We set the autoCreateGaps and autoCreateContainerGaps properties to true to add gaps between the components and between the components and the edges of the container.

Next, we use the createSequentialGroup method to create a horizontal group that specifies how the components should be arranged horizontally. We group the username label and password label together and group the username field, password field, and login button together.

We use the createSequentialGroup method again to create a vertical group that specifies how the components should be arranged vertically. We group the username label and username field together, the password label and password field together, and the login button by itself.

Finally, we call pack() to resize the frame to fit its components, and setVisible(true) to make it visible. When we run this example, we'll see a login form with the components arranged using the GroupLayout manager.