The JSpinner is a user interface widget in Swing which allows the user to select a value from a list of predetermined values. It is similar to a combo box, but allows the user to increment or decrement the selected value using up/down arrows or the mouse scroll wheel. The JSpinner can be used to select a range of values, such as dates or numbers.

Here is an example of how to create and use a JSpinner in Java:

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

public class JSpinnerExample {
    public static void main(String[] args) {
        JFrame frame = new JFrame("JSpinner Example");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        // create a spinner with a list of values
        String[] values = { "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday", "Sunday" };
        JSpinner spinner = new JSpinner(new SpinnerListModel(values));

        // create a spinner with a range of values
        SpinnerNumberModel model = new SpinnerNumberModel(0, 0, 100, 1);
        JSpinner rangeSpinner = new JSpinner(model);

        // add the spinners to the frame
        JPanel panel = new JPanel(new GridLayout(2, 2));
        panel.add(new JLabel("Select a day of the week: "));
        panel.add(spinner);
        panel.add(new JLabel("Select a number between 0 and 100: "));
        panel.add(rangeSpinner);
        frame.getContentPane().add(panel);

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

This code creates a frame with two spinners: one with a list of days of the week, and one with a range of numbers from 0 to 100. The JSpinner class has several constructors which take different types of SpinnerModel objects to define the values and behavior of the spinner.