Question

I’m new to android (and java) and I am wondering what’s the mechanism to communicate between objects? Like if I want to monitor a private member’s value, if it changes, I want a method to be triggered.

I know for UI event there’s event listener. But what if it’s not a mouse click, but a private member’s value changing? I tried intent/broadcastreceiver, but i don’t think that’s for what I want to do..

Thank you so much!!

Answer 1

You can use publisher subscriber based approach here. Your class which contains the private (Publisher) member will have a method RegisterForChange that method you will take some interface ISomeInterface as a parameter and the Subscriber class would have implemented that interface. Once there is a change in private member you can call SomeMethod method of that interface to notify the Subscriber that my private member has been changed

 //pseudocode
    public interface ISomeInterface
    {
        SomeMethod();
    }

    class Publisher 
    {
        RegisterForChange(ISomeInterface inter)
        {
            inter.SomeMEthod();
        }

        //whenever there is change call 
        inter.SomeMethod();
    }

    class Subsscriber implements ISomeInterface
    {
        //inside this class register for change by calling
        Publisher.RegsiterForChange(this);

        // this method will be called whenever there is change in private member
        public SomeMethod()
        {
        }
    }