TreeSet in JAVA

TreeSet implements NavigableSet interface which extends SortedSet interface.
Treeset does not supports duplicates. So it contains unique elements only.

Following is the hierarchy of HashSet:

Iterable

  | extends
  |

Collection
  
  | extends
  |

 Set

  | implements
  |

SortedSet

  | extends
  |

NavigableSet

  | implements
  |

TreeSet

Example:

/**
 * Tree set supports same types of objects. If we add String it will
 * throw exception java.lang.Integer cannot be cast to java.lang.String
 * Set support duplicate values while adding but it does not iterate
 * through duplicates.
 */

TreeSet set111 = new TreeSet();
set111.add(new Integer(1111));
set111.add(new Integer(155551));
set111.add(new Integer(111));
set111.add(new Integer(1111));// Duplicate value
// set111.add("krishna");
Iterator iterator22 = set111.iterator();
while (iterator22.hasNext()) {
System.out.println("%%%%%%%@@@@@@"+ iterator22.next());

}

/**
 * Tree set will iterate the values in ascending order. Tree set does
 * not supports different types of objects.
 */
Set set22 = new TreeSet();
set22.add("munna");
set22.add("krishna");
set22.add("anusha");
set22.add("kusuma");
Iterator iterator21 = set22.iterator();
while (iterator21.hasNext()) {
System.out.println(iterator21.next());
}