This change “enforces” using callbacks in a way which prevents memory leaks. But since this was essentially undocumented all along this change opens up a more interesting question. Is this change part of under the hood reorganizations in preparation for HG2? Or possibly a movement towards aligning java support with MCOS and away from UDD?

Maybe both, I don’t know…

For the record, I miss UDD’s ability to dynamically control/add class properties (schema.prop et al) in run time. It’s causing me a lot of headaches migrating some of my code to HG2.

I’ve just run the above example and it works without the update; Have MATLAB patched R2014a. my version reports 8.3.0.532 (R2014a)?

Also the EventTest example does not work/without the update:

>> evt = javaObjectEDT(nujira.EventTest)
evt =
nujira.EventTest@64902cf8
 
>> evt = handle(evt, 'CallbackProperties')
evt =
	javahandle_withcallbacks.nujira.EventTest

>> get(evt)
                    Class: [1x1 java.lang.Class]
        TestEventCallback: []
    TestEventCallbackData: []

>> set(evt,'TestEventCallback',@(h,e)disp(h))
java.lang.NullPointerException
	at com.mathworks.jmi.bean.MatlabBeanInterface.addCallback(MatlabBeanInterface.java:484)
	at com.mathworks.jmi.bean.MatlabCallbackInterface.addCallback(MatlabCallbackInterface.java:130)

Any pointers?

@Sean – as I explained ^[13], you need to place the relevant class folder/JAR in Matlab’s static Java classpath.

Thank you, using the static path worked (but I had to use “javaclasspath.txt” in the prefdir() instead). The callback now sets, but the value looks wrong:

>> set(evt,'TestEventCallback',@(h,e)disp(h))
>> get(evt)
                    Class: [1x1 java.lang.Class]
        TestEventCallback: @(h,e)disp(h)
    TestEventCallbackData: []

>> evt.notifyMyTest
	javahandle_withcallbacks.nujira.EventTest

Your example showed:

>> set(evt,'TestEventCallback',@(h,e)disp(h))
>> get(evt)
	Class = [ (1 by 1) java.lang.Class array]
	TestEventCallback = [ (1 by 1) function_handle array]
	TestEventCallbackData = []

>> evt.notifyMyTest   % invoke Java event
              0.0009765625   % Matlab callback

We are nearly there.
PS: I do have a copy of your book which has been very helpful.

This is due to the difference between running platforms and/or Matlab releases. If you’d like my assistance in helping you on your specific platform, contact me offline for a consulting proposal.

Running Matlab 2014b, I had the same problem the Sean Lynch posted:

>> h_evt = handle(evt, 'CallbackProperties');
>> set(h_evt,'TestEventCallback',@(h,e)disp(h))
>> get(h_evt)
                    Class: [1x1 java.lang.Class]
        TestEventCallback: @(h,e)disp(h)
    TestEventCallbackData: []

>> evt.notifyMyTest
	javahandle_withcallbacks.EventTest

But trying something like

>> set(h_evt,'TestEventCallback',@(h,e)disp('test'))
>> h_evt.notifyMyTest
test

demonstrates that it is working. One step at a time.

Thank you! This article helped a lot as well as the previous article: ^[14].

I ran into a problem from using java 7 that took a while to discover so I thought I’d share it. Hopefully it helps those with the same problem in the future.

>> jScrollbar = javaObjectEDT('javax.swing.JScrollBar');
>> hjScrollbar = handle(jScrollbar,'CallbackProperties');
>> set(hjScrollbar, 'StateChangedCallback', callback);
Error using javahandle_withcallbacks.javax.swing.JScrollBar/set
The name 'StateChangedCallback' is not an accessible property for an instance of class 'javax.swing.JScrollBar'. 
 
>> ver
...
Java Version: Java 1.7.0_11-b21 with Oracle Corporation Java HotSpot(TM) 64-Bit Server VM mixed mode
...

The problem is java 7 has changed the interface to the component and it is no longer a state change event but an adjustment event.
(see ^[15]). It is corrected by using hjScroll.AdjustmentValueChangedCallback in this example. Be on the lookout for these types of changes in the java interface.

Does anyone know how to get the window events like window closing using this method?

jFigPeer = get(handle(gcf),'JavaFrame');
jFrame = handle(jFigPeer.fHG2Client.getWindow, 'CallbackProperties');
jFrame.WindowClosingCallback = @myCallback;

Is there a clean way to do it from when your loading a .jar file?

For example I have a .jar file called test.jar
I call it like jFrame=test(); after adding it to the dynamic Java classpath
but that jFrame doesnt have properties to getWindow or JavaFrame?

JAR files contain Java classes, not Matlab figures. The entire blog here discusses Matlab.

How do I get delimiter of the date format ?

example :
system foramt – 1/23/2017
Get Output from your script – mm dd,yyyy

I need output like – dd/mm/yyyy

Thanks in Advance

You can either use the Java ^[16] class to convert the date format into your desired output format (read the Java docs online to see how to do this), or use Matlab’s datenum and datestr functions with the appropriate format specifiers (read the corresponding Matlab docs to see how to do this).

This looks elegant. Thank you. One issue I am not able to sort out – on maximizing the figure window the location of “javax.swing.JSlider” object does not scale properly?Is there a way to specify the ‘Units’,’normalize’ property like we do in uicontrol() to maintain the scaling and location.

The ^[17] returns 2 objects: a Java reference and a Matlab container. Simply set the value of the Units property of the Matlab container to ‘normalized’:

[hjSlider, hContainer] = javacomponent(javax.swing.JSlider, pixelPosition, gcf);
hContainer.Units = 'normalized';