observer-snippet

observer-snippet.java

public class ObserverActivity extends Activity implements Observer{
    ...
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        ...
        MyObservable myObservable = new MyObservable();
        // Registering of the observer (here the activity)
        myObservable.addObserver(this);
        // Changing the state of the observable
        myObservable.setValue("Hello ! ");
    }

    // Update of the observer on a state change notification
    @Override
    public void update(Observable observable, Object data) {
        textView.setText(((MyObservable)observable).getValue());
    }

    class MyObservable extends Observable {

        private String mValue;

        public String getValue() {
            return mValue;
        }

        public void setValue(String mValue) {
            this.mValue = mValue;
            // Mark the change of state
            setChanged();
            // Notification of the change for update
            notifyObservers();
        }
    }
}