package java.util; public class Observable{ public Observable() { throw new RuntimeException("skeleton method"); } public synchronized void addObserver(Observer a1) { throw new RuntimeException("skeleton method"); } public synchronized void deleteObserver(Observer a1) { throw new RuntimeException("skeleton method"); } public void notifyObservers() { throw new RuntimeException("skeleton method"); } public void notifyObservers(Object a1) { throw new RuntimeException("skeleton method"); } public synchronized void deleteObservers() { throw new RuntimeException("skeleton method"); } public synchronized boolean hasChanged() { throw new RuntimeException("skeleton method"); } public synchronized int countObservers() { throw new RuntimeException("skeleton method"); } }