Collection interface

Collection interface

• If we want to represent a group of individual objects as a single entity then we should go for Collection interface.
• Collection interface defines the most common general methods which can be applicable for any Collection object.
• The following is the list of methods present in Collection interface.

1. boolean add(Object o);
2. boolean addAll(Collection c);
3. boolean remove(Object o);
4. boolean removeAll(Object o);
5. boolean retainAll(Collection c); // To remove all objects except those present in c.
6. void clear();
7. boolean contains(Object o);
8. boolean containsAll(Collection c);
9. boolean isEmpty();
10. int size();
11. Object[] toArray();
12. Iterator iterator();

  There is no concrete class which implements Collection interface directly.