Synchronized Methods problem!

Hi,

I have an assignment that needs to use synchronized methods, what I have to do is create a supermarket app in Java where I set a favourite item/product's ID and retrieve it however those two methods need to use synchronized methods. Also I am using a GUI, so how do I implement that into two buttons?

e.g. Set Favourte, Retrieve Favourite?

Code Java:

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   private void jButton3ActionPerformed(java.awt.event.ActionEvent evt) {                                         
 
    }                                        
 
    private void jButton6ActionPerformed(java.awt.event.ActionEvent evt) {                                         
 
    }   
 
 synchronized public void retrieveFav()throws InterruptedException {
 
    }
 
    synchronized public void setFav()throws InterruptedException {
 
    }

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See the following link: Using Synchronized Methods
I presume you need to synchronize the method because of multithreading (you don't mention threads at all)? If so, be careful making calls to a Swing GUI - all processes unless otherwise noted in the API should be placed onto the swing event dispatch thread (see Swing and Threads