Solved

Using JComponent.firePropertyChange() with a Swing component

Posted on 1998-07-28
6
2,345 Views
Last Modified: 2006-11-17
Can someone (in detail) how to set up objects to use the JComponent.firePropertyChange() method when and "action" is performed? Specifically, I have a object (extending from JPanel) that contains a JComboBox. I'd like to have other objects "listen" to this JComboBox to change and automatically do something with the new value.

Source code of an example would be greatly appreciated.
0
Comment
Question by:mwalker
  • 4
  • 2
6 Comments
 

Author Comment

by:mwalker
ID: 1228848
Edited text of question
0
 

Author Comment

by:mwalker
ID: 1228849
Edited text of question
0
 
LVL 5

Accepted Solution

by:
msmolyak earned 150 total points
ID: 1228850
You should define listeners (the classes interested in property change event) by implementing java.beans.PropertyChangeListener interface (which has the propertyChanged() method).

Next step is to register the listener class with the component whose property change events you want to intercept by using JComponent.addPropertyListener() method.

The last step is notifying the registered listeners about the property change. For instance, in the method setCoffeeStrength() which changes the coffeeStrength property value you call the method firePropertyChange("coffeeStrength", oldStrength, newStrength).  This in turn calls the propertyChanged() method of all the registered listeners passing the property name and the old and new values. The listeners decides what to do about this change (depending on how you implement propertyChanged() method).

firePropertyChanged() method is overloaded to cover all the possible property types.

Hope that helps.
0
Is Your Active Directory as Secure as You Think?

More than 75% of all records are compromised because of the loss or theft of a privileged credential. Experts have been exploring Active Directory infrastructure to identify key threats and establish best practices for keeping data safe. Attend this month’s webinar to learn more.

 

Author Comment

by:mwalker
ID: 1228851
This is good, but, I'm not clear on your example.  When does setCoffeeStrength() get called?  In my case, I have a ActionListener defined on the JComboBox. Would I call the method firePropertyChange("coffeeStrength", oldStrength, newStrength) here?
0
 
LVL 5

Expert Comment

by:msmolyak
ID: 1228852
In my example the property change was initiated by someone calling setCoffeeStrength().  In your case you want to link the notification to the value selected in the combo box. Rather than using property change mechanism you can use the item listeners. It is even simpler.

Your listener will implement the ItemListener interface. Then you add the listener(s) to the combo box using addItemListener() method. When the selection changes the listener is AUTOMATICALLY notified (that  the method fireItemStateChanged() method gets called for you, you do not have to call it. This method will tell the listener what the event source is as well as the old and new selection.

Is that what you want?
0
 

Author Comment

by:mwalker
ID: 1228853
Yes.  Thank you.
0

Featured Post

Is Your Active Directory as Secure as You Think?

More than 75% of all records are compromised because of the loss or theft of a privileged credential. Experts have been exploring Active Directory infrastructure to identify key threats and establish best practices for keeping data safe. Attend this month’s webinar to learn more.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

Title # Comments Views Activity
solarwind tftp server 2 45
Java Loop 6 50
fibonacci ten numbers 4 30
reverse digits of a number using for loop 5 36
Are you developing a Java application and want to create Excel Spreadsheets? You have come to the right place, this article will describe how you can create Excel Spreadsheets from a Java Application. For the purposes of this article, I will be u…
In this post we will learn how to connect and configure Android Device (Smartphone etc.) with Android Studio. After that we will run a simple Hello World Program.
Viewers learn about the “for” loop and how it works in Java. By comparing it to the while loop learned before, viewers can make the transition easily. You will learn about the formatting of the for loop as we write a program that prints even numbers…
Viewers will learn one way to get user input in Java. Introduce the Scanner object: Declare the variable that stores the user input: An example prompting the user for input: Methods you need to invoke in order to properly get  user input:

863 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question

Need Help in Real-Time?

Connect with top rated Experts

23 Experts available now in Live!

Get 1:1 Help Now