1. What is TreeSet colletion in java ?
- Elements in TreeSet are ordered using natural order or Comparator provided.
- e.g. TreeSet containing integers will be sorted in natural order
- e.g TreeSet containing user defined objects will be sorted using comparator supplied.
- TreeSet is a NavigableSet implementation based on a TreeMap.
- TreeSet is red black tree based implementation.
- TreeSet is Red black tree implementation.
- TreeSet provides guaranteed log(n) cost for the basic operations (add, remove & contains).
- TreeSet contains unique element like HashSet.
- null elements are not allowed in TreeSet.
- TreeSet is not thread safe like HashSet, LinkedHashSet, EnumSet etc.
- Iterator of TreeSet is fail-fast.
- Iterator will throw ConcurrentModificationException, if TreeSet modified at any time after the iterator is created, in any way except through the iterator’s own remove method.
2. TreeSet collection class hierarchy:
3. Program – TreeSet collection of integers & characters in java (example)
package org.learn.collection.set.tset;import java.util.Set;import java.util.TreeSet;public class DemoTreeSet { public static void main(String[] args) { Set<Integer> natualOrderNumber = new TreeSet<>(); natualOrderNumber.add(100); natualOrderNumber.add(50); natualOrderNumber.add(40); natualOrderNumber.add(200); natualOrderNumber.add(10); System.out.println("1. Natual order integers in TreeSet: \n"+ natualOrderNumber); Set<Character> natualOrderCharacter = new TreeSet<>(); natualOrderCharacter.add('J'); natualOrderCharacter.add('A'); natualOrderCharacter.add('V'); natualOrderCharacter.add('A'); System.out.println("2. Natual order characters in TreeSet: \n"+ natualOrderCharacter); } } |
4. Output – TreeSet collection of integers & characters in java (example)
1. Natual order integers in TreeSet: [10, 40, 50, 100, 200]2. Natual order characters in TreeSet: [A, J, V] |