2. Collections

Overview

• Collection is a set of items or objects.

Java Collections

java.util.Collection

• The Java Collections Framework, comprises a sophisticated set of interfaces and classes designed for handling collections of objects.

  

  • List extends (child of) Collection

    public interface List<E> extends Collection<E>
    

    • Allows duplicates
    • Introduces positional indexing

  • Set extends (child of) Collection

    public interface Set<E> extends Collection<E>
    

    • Does NOT allow duplicates

  • Map does NOT extend (not child of) Collection, but still considered to be part of the Java Collection framework.

    public interface Map<K, V>
    

    • Collection of key-value pairs.
    • Does NOT allow duplicate keys

• Interface Implementations

  Interface	Implementation
  List	ArrayList, LinkedList
  Set	HashSet, TreeSet
  Map	HashMap, TreeMap

Common Operations of Collections

• Insert
• Delete
• Sort
• Search
• Traverse
• Copy / Clone

Back to Home Next Lecture