Using spinners in Matlab GUI

One of the few standard Java Swing controls that does not have any Matlab uicontrol counterpart is JSpinner. JSpinner is basically an editbox with two tiny adjacent up/down buttons. Spinners are similar in functionality to a combo-box (a.k.a. drop-down or pop-up menu), where a user can switch between several pre-selected values. They are often used when the list of possible values is too large to display in a combo-box menu. Like combo-boxes, spinners too can be editable (meaning that the user can type a value in the editbox) or not (the user can only “spin” the value using the up/down buttons).

JSpinner uses an internal data model, similarly to JTree, JTable and other complex controls. The default model is SpinnerNumberModel, which defines a min/max value (unlimited=[] by default) and step-size (1 by default). Additional predefined models are SpinnerListModel (which accepts a cell array of possible string values) and SpinnerDateModel (which defines a date range and step unit).

Here’s a basic code snippet showing how to display a simple numeric spinner for numbers between 20 and 35, with an initial value of 24 and increments of 1:

jModel = javax.swing.SpinnerNumberModel(24,20,35,1);
jSpinner = javax.swing.JSpinner(jModel);
jhSpinner = javacomponent(jSpinner, [10,10,60,20], gcf);

The spinner value can be set using the edit-box or by clicking on one of the tiny arrow buttons, or programmatically by setting the Value property. The spinner object also has related read-only properties NextValue and PreviousValue. The spinner’s model object has the corresponding Value (settable), NextValue (read-only) and PreviousValue (read-only) properties. In addition, the model also has the settable Maximum, Minimum and StepSize properties.

To attach a data-change callback, set the spinner’s StateChangedCallback property.

I have created a small Matlab demo, SpinnerDemo, which demonstrates usage of JSpinner in Matlab figures. Each of the three predefined models (number, list, and date) is presented, and the spinner values are inter-connected via their callbacks. The Matlab code is modeled after the Java code that is used to document JSpinner in the official documentation. Readers are welcome to download this demo from the Matlab File Exchange and reuse its source code.

Java's SpinnerDemo

  

My Matlab SpinnerDemo

As can be seen from the screenshot, SpinnerDemo also demonstrates how to attach a label to a GUI control with an associated accelerator key (Alt-D in the screenshot example, which sets the focus to the Date control).

An internal component in Matlab, namely com.mathworks.mwswing.MJSpinner, extends javax.swing.JSpinner, but in this particular case I cannot see any big advantage of using the internal MJSpinner rather than the standard JSpinner. On the contrary, using JSpinner will likely improve forward compatibility – MathWorks may well change MJSpinner in the future, but it cannot do anything to the standard Swing JSpinner. In other cases, internal Matlab controls do offer significant advantages over the standard Swing controls, but not here it would seem. In any case, the SpinnerDemo utility uses MJSpinner, but you can safely use JSpinner instead (line #86).

The internal Matlab controls are discussed in detail in Chapter 5 of my Matlab-Java book, and MJSpinner is specifically discussed in section 5.2.1.

Another JSpinner derivative is JIDE’s com.jidesoft.grid.SpinnerCellEditor, which can be used as the cell-editor component in tables. An example of this was shown in the article about Advanced JIDE Property Grids (and section 5.7.5 in the book). You may also be interested in the com.jidesoft.combobox.DateSpinnerComboBox, which presents a control that includes both a date-selection combo-box and a spinner (section 5.7.2):

A property grid with spinner control

  

JIDE's DateSpinnerComboBox

Related posts:

1. Customizing Matlab labels Matlab's text uicontrol is not very customizable, and does not support HTML or Tex formatting. This article shows how to display HTML labels in Matlab and some undocumented customizations...
2. Matlab-Java interface using a static control The switchyard function design pattern can be very useful when setting Matlab callbacks to Java GUI controls. This article explains why and how....
3. Advanced JIDE Property Grids JIDE property grids can use complex cell renderer and editor components and can signal property change events asynchronously to Matlab callbacks...
4. Blurred Matlab figure window Matlab figure windows can be blurred using a semi-transparent overlaid window - this article explains how...
5. Rich Matlab editbox contents The Matlab editbox uicontrol does not handle HTML contents as do other uicontrols. In this article I show how this limitation can be removed....
6. FindJObj – find a Matlab component’s underlying Java object The FindJObj utility can be used to access and display the internal components of Matlab controls and containers. This article explains its uses and inner mechanism....