In Java Swing, JTextField is a GUI component that allows users to input a single line of text. It is a part of the javax.swing package and extends JTextComponent.

Here's a basic example of how to create a JTextField:

import javax.swing.*;

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

        // create a JTextField with default text and size
        JTextField textField = new JTextField("Enter text here", 20);

        // add the JTextField to the frame
        frame.getContentPane().add(textField);

        // set the size and make the frame visible
        frame.setSize(300, 200);
        frame.setVisible(true);
    }
}

In this example, we create a new JFrame and a new JTextField with the default text "Enter text here" and a size of 20 characters. We add the JTextField to the JFrame and set the size of the JFrame before making it visible.

You can also add an ActionListener to the JTextField to perform an action when the user presses the "Enter" key. Here's an example:

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

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

        // create a JTextField with default text and size
        JTextField textField = new JTextField("Enter text here", 20);

        // add an ActionListener to the JTextField
        textField.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                System.out.println(textField.getText());
            }
        });

        // add the JTextField to the frame
        frame.getContentPane().add(textField);

        // set the size and make the frame visible
        frame.setSize(300, 200);
        frame.setVisible(true);
    }
}

In this example, we add an ActionListener to the JTextField that prints the text in the JTextField when the user presses the "Enter" key.