AbstractCollection Class in Java

AbstractCollection Class in Java

AbstractCollection is part of the Java Collection Framework and implements the Collection interface. It offers a skeletal implementation of that interface, providing ready-made versions of several methods so you don't need to code each one yourself. Put simply, it cuts down the work involved in creating your own collection.

The class is declared as public abstract class AbstractCollection<E> implements Collection<E>, where E represents the type of elements the collection stores.

Benefits of Using AbstractCollection

• Unmodifiable collections: To build a collection that cannot be changed (like an immutable list), extend AbstractCollection and implement just the iterator() and size() methods.
• Modifiable collections: For a collection that can be changed (such as an ArrayList), you need those same two methods plus an override of add(). Without that override, calling add() throws an UnsupportedOperationException.

Constructor

A default constructor is available, but because it is protected you cannot create an AbstractCollection instance directly.

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