How to use Spinners in Java?

[Damien25]

Hi friends,
I am new to the Java programming language. Before I have used the combo boxes but I want something that can scroll up also. This can be done by using the Spinners. But I don't know the coding for that and also I don't know anything about the Spinners.!! So please tell me how to use Spinners in Java.?? please help me as soon as possible.!!

[Allan.d]

If you have observed carefully then you should know that spinners are similar to combo boxes and lists. the similar things are that in both user can choose option from a range of values. Spinners allow the user to type in a value, just like you did in editable combo boxes.!! The difference between the two is that the spinners do not have a drop-down list that can cover up other components like the combo boxes. Only the current value is visible in spinner since they do not display possible values. When the set of possible values is extremely large, spinners are oftenly used instead of combo boxes or lists.

[Warner]

The following code would help you for creating the spinner :

import javax.swing.*;
import java.awt.Color;
import java.awt.Container;
import java.util.Calendar;
import java.util.Date;

public class SpinnerDemo extends JPanel {
    public SpinnerDemo(boolean cycleMonths) {
        super(new SpringLayout());

        String[] labels = {"Month: ", "Year: ", "Another Date: "};
        int numPairs = labels.length;
        Calendar calendar = Calendar.getInstance();
        JFormattedTextField ftf = null;

        String[] monthStrings = getMonthStrings(); //get month names
        SpinnerListModel monthModel = null;
        if (cycleMonths) { //use custom model
            monthModel = new CyclingSpinnerListModel(monthStrings);
        } else { //use standard model
            monthModel = new SpinnerListModel(monthStrings);
        }
        JSpinner spinner = addLabeledSpinner(this,
                                             labels[0],
                                             monthModel);
        ftf = getTextField(spinner);
        if (ftf != null ) {
            ftf.setColumns(8); //specify more width than we need
            ftf.setHorizontalAlignment(JTextField.RIGHT);
        }

        int currentYear = calendar.get(Calendar.YEAR);
        SpinnerModel yearModel = new SpinnerNumberModel(currentYear, 
                                       currentYear - 100, 
                                       currentYear + 100, 
                                       1);                

        if (monthModel instanceof CyclingSpinnerListModel) {
            ((CyclingSpinnerListModel)monthModel).setLinkedModel(yearModel);
        }
        spinner = addLabeledSpinner(this, labels[1], yearModel);
        spinner.setEditor(new JSpinner.NumberEditor(spinner, "#"));

        Date initDate = calendar.getTime();
        calendar.add(Calendar.YEAR, -100);
        Date earliestDate = calendar.getTime();
        calendar.add(Calendar.YEAR, 200);
        Date latestDate = calendar.getTime();
        SpinnerModel dateModel = new SpinnerDateModel(initDate,
                                     earliestDate,
                                     latestDate,
                                     Calendar.YEAR);//ignored for user input
        spinner = addLabeledSpinner(this, labels[2], dateModel);
        spinner.setEditor(new JSpinner.DateEditor(spinner, "MM/yyyy"));

        SpringUtilities.makeCompactGrid(this,
                                        numPairs, 2, 
                                        10, 10,        
                                        6, 10);
    }

[Viensterrr]

You will have to return the formatted text field used by the editor then only the code of spinner will work properly. If the editor doesn't descend from JSpinner.DefaultEditor, then you will have to return Null. The following is the code for the same :

    public JFormattedTextField getTextField(JSpinner spinner) {
        JComponent editor = spinner.getEditor();
        if (editor instanceof JSpinner.DefaultEditor) {
            return ((JSpinner.DefaultEditor)editor).getTextField();
        } else {
            System.err.println("Unexpected editor type: "
                               + spinner.getEditor().getClass()
                               + " isn't a descendant of DefaultEditor");
            return null;
        }
    }

[kyosang]

I think that you should be pretty clear with using the Spinners in Java.
Many times you need to create the GUI and show it. If you invoke this method from the event dispatch thread then your thread would be more safe. The following coding explains the same :

private static void createAndShowGUI() {
        JFrame frame = new JFrame("SpinnerDemo");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        frame.add(new SpinnerDemo(false));

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

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            public void run() {
	        UIManager.put("swing.boldMetal", Boolean.FALSE);
		createAndShowGUI();
            }
        });
    }
}