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Thread: share data from methods

  1. #1
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    Default 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!


  2. #2
    Super Moderator curmudgeon's Avatar
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    Default Re: share data from methods

    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.

  3. #3
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    Default Re: share data from methods

    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.

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    Default Re: share data from methods

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

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    Default Re: share data from methods

    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!

  6. #6
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    Default Re: share data from methods

    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.

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    Default Re: share data from methods

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

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