Still celebrating National IT Professionals Day with 3 months of free Premium Membership. Use Code ITDAY17

x
?
Solved

Android component listener

Posted on 2013-05-11
2
Medium Priority
?
474 Views
Last Modified: 2013-05-15
I have a 'trick' that I do sometimes in Java/Swing in which I create a swing component that is always invisible and it may have any number of event listeners attached to it. When a variable or variables changes value, the code will cause that component to change and anything listening will know that those variable(s) have change.

I want to do this same thing in Android. What would I use instead of the swing component?
0
Comment
Question by:allelopath
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
2 Comments
 
LVL 28

Accepted Solution

by:
dpearson earned 2000 total points
ID: 39160341
I think for Android this would be a case of building your own.  It doesn't sound very complicated - I think it would be something like:

public class DataStore {
     private List<UpdateListener> m_Listeners = new ArrayList<UpdateListener>() ;

     private Object m_Value ;

     public Object getValue() { return m_Value ; }
     public void setValue(Object newValue) { m_Value = newValue ; notifyListeners() ; }

     public void addListener(UpdateListener listener) { m_Listeners.add(listener) ; }
     public void removeListener(UpdateListener listener) { m_Listeners.remove(listener) ; }

     private void notifyListeners() {
          for (UpdateListener listener : m_Listeners) {
              try {
                  listener.dataValueChanged(this) ;
             } catch (Exception ex) { // Should log this }
          }
     }
}

Then your listeners would implement the interface:

interface UpdateListener {
    public void dataValueChanged(DataStore store) ;
}

and be notified any time the value was changed.

If you want to do this but make it typesafe (instead of just storing and getting an Object), you could use generics for the type instead of "Object" but it's the same pattern either way.

Doug
0
 
LVL 1

Author Comment

by:allelopath
ID: 39169317
Thanks, you are correct, one has to 'roll his own'
0

Featured Post

Build and deliver software with DevOps

A digital transformation requires faster time to market, shorter software development lifecycles, and the ability to adapt rapidly to changing customer demands. DevOps provides the solution.

Question has a verified solution.

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

The case of the missing phone talks about the way a small electronic gadget (the mobile phone) has penetrated into our lives and has made us addicted to it.
Basic understanding on "OO- Object Orientation" is needed for designing a logical solution to solve a problem. Basic OOAD is a prerequisite for a coder to ensure that they follow the basic design of OO. This would help developers to understand the b…
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 about the regular for loop in Java and how to use it. Definition: Break the for loop down into 3 parts: Syntax when using for loops: Example using a for loop:
Suggested Courses

721 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