Collection in Java

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 In Java, a collection is a group of objects that are stored and manipulated together as a single unit. Collections in Java are implemented through a set of interfaces and classes that provide different ways to organize and manipulate data.

The most commonly used interfaces in the Java Collections Framework are:

  1. List: An ordered collection of elements that can contain duplicates.
  2. Set: An unordered collection of elements that does not allow duplicates.
  3. Queue: A collection that orders its elements in a specific way and allows for element insertion and removal at the head or tail of the queue.
  4. Map: A collection that maps keys to values, where each key can only map to one value.

Some of the commonly used classes that implement these interfaces are:

  1. ArrayList: A resizable array that implements the List interface.
  2. LinkedList: A linked list that implements the List and Queue interfaces.
  3. HashSet: A set that uses a hash table to store its elements.
  4. HashMap: A map that uses a hash table to store its key-value pairs.

Collections in Java provide several benefits such as:

  1. Dynamic resizing: The size of a collection can be dynamically adjusted as elements are added or removed.
  2. Efficient algorithms: Java Collections Framework provides efficient algorithms for searching, sorting, and filtering elements in a collection.
  3. Type safety: Java Collections Framework provides type safety through the use of generics, which ensures that only elements of a specified type can be added to a collection.
  4. Interoperability: Collections in Java can be easily converted to and from arrays, allowing for easy integration with other parts of the Java ecosystem.

Overall, Java Collections Framework provides a powerful and flexible way to work with groups of related objects in Java.

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