share data from methods

Hi all and sorry for my question :-(

I've this sample code:

public class ShareVar {
public static void main(String[] args) {

System.out.println("Number is: "+c);

}

private static int Calc(){
int a=10; int b=3; int c;
c=a+b;
return c;
}
}

variable c is not shared to main class

How allow c be share in whole code?

thanks!

If this were my assignment, I'd call the calc() method (note that since it's a method, its first letter should be lower-case not upper-case) inside of the main method, and then I'd display the value that it returns.

thank you :-) I need use the variable c by main code and not print it. (This code in only sample) - So I need use that variable in the main code.

Please print your actual assignment, word for word. Let's see exactly what you have to do before giving incorrect advice.

Ok (and sorry for my english) I build an android app and I've an auto-refresh textview (its get external ip address every 5 seconds).

The method that check external ip is same of calc() method. In the main code I need handle that variable (like c) in other way but c in not available.

Thanks!

I would suggest that you use an observer pattern to achieve this, and something like this can be done easily using PropertyChangeSupport and PropertyChangeListeners:

• Make the field listened, the one that holds the external ip value, to a "bound property", say called externalIp.
• That is, make it a private field of the class: private String externalIp = "";
• Give this class a public String getExternalIp() method that returns the current value of externalIp.
• Give the class a PropertyChangeSupport instance
• Give the class both an addPropertyChangeListener(PropertyChangeListener listener) and a removePropertyChangeListener(PropertyChangeListene r listener), and add or remove the listener from the PropertyChangeSupport instance in these methods.
• Give your class a public setExternalIp(String newValue) method.
• Inside of this method, call firePropertyChange(propertyName, oldValue, newValue) after setting the newValue to notify the listeners.
• Then any object that wants to listen to and respond changes in the externalIp value can add a PropertyChangeListener to the object of this class, and then get the newest externalIp String whenever it has been notified of change.

wow! I'm going to study... very thanks!