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The Set interface is a part of the Java Collection Framework and is used to store a collection of unique elements. Unlike List, it does not allow duplicate values and does not maintain insertion order.


Block Diagram of Set Interface


  • <<       >>      : Denotes an Interface
  • <          >        : Denotes a Class
  • ---------->      : Represents Implementation

Implementation Classes of Set Interface

1.  HashSet

  • Uses HashTable for storage.
  • Does not maintain insertion order.
  • Provides constant-time performance for add, remove, and search operations.

2.  LinkedHashSet

  • Maintains insertion order.
  • Slower than HashSet due to ordering maintenance.

3.  TreeSet

  • Stores element in sorted order (ascending by default).
  • Imlements NavigableSet, allowing range-based operations.

Key Point

  • Set is a type of collection that stores only unique elements. It doesn't allow duplicate elements.
  • It doesn't have Index i.e. elements stored randomly.
  • The Set doesn't maintain the order of insertion.
  • The elements of the Set can be accessed either by using enhanced for loop or Iterator.