Call a method on all classes that implements that method

Question

I have an Activity and 10 fragments. I've created an interface and implement it on all Fragments. How can I call that method on all Fragments from the Activity?

  public interface OnConnectListener {
      void isDeviceConnected(boolean b);
  }

UPDATE:

Using your suggestions I did this:

public void isDeviceConnected(boolean b, List fragmentList) {
    for (OnConnectListener listener : getOnConnectListeners(fragmentList)) {
        listener.isDeviceConnected(b);
    }
}

public List<OnConnectListener> getOnConnectListeners(List fragmentList) {
    List<OnConnectListener> listeners = new ArrayList<>();
    for (Object o : fragmentList) {
        if (o instanceof OnConnectListener) {
            listeners.add((OnConnectListener) o);
        }
    }
    return listeners;
}

Now I just use:

isDeviceConnected(true, fragmentList);

Thank you so much.

Answer 1

Assuming your "Activity" class holds a reference of 10 "onConnectListener" instances, you can loop thru each and call isDeviceConnected like so:

private List<onConnectListener> onConnectListeners;
....
for(onConnectListener onConnectListener: onConnectListeners) {
    onConnectListener.isDeviceConnected(true); // or false
}

By the way: Java naming conventions state that class names start with capital letters, and iterfaces usually start with the letter "I" So its best if you name your interface IOnConnectListener

Answer 2

This is perfect case for Observer pattern

http://www.oodesign.com/observer-pattern.html