Can you listen for a string value to change?

Question

Is there any easy way to see if a string changes value? I have a public static string in one instance of a class that I wish to be notified when it changes. An object of another class will have the listener.
Edited by: sarcasteak on Dec 8, 2009 1:40 PM

Answer 1

jverd wrote:
sarcasteak wrote:
jverd wrote:
sarcasteak wrote:
In the class that has the value, I create a new ObservableValue object and in the constructor I pass it the string. Now whenever I update the value I assume I do ov.setValue(search), so then the class that wants to get this value would implement observer.. but how does it get access to the ov instance?It registers itself as an observer. Did you read up on Observer/Observable?An observer for just that one instance of the ObvservableValue?Yes.
The problem is that I am not sure how to access the value from the secondary class.Your Observer must have an update() method. You understand that you have to implement the Observer interface, right? And you understand that to do so, you have to provide that method right? Have you looked at that method's signature? It provides you a reference to the Observable. You just cast it to whatever your class is and call the get method for the property you're interested in.
I understand that I need to add the observer, but I am not sure how I can do that if the secondary class(object) isn't being instantiated in the same object that passes the value.I have no idea what you mean by the last half of that sentence.
Have you tried maybe googling for java observer observable pattern? I'm sure there are plenty of examples available.Thanks, but I just ended up taking the easy way out and using an eclipse preference to pass values back and forth, not ideal since the values change so much.