Java Treeset


  • This Java Treeset class implements the Set interface and guarantees that the sorted set will be in ascending element order, sorted according to the natural order of the elements or by the comparator provided at set creation time, depending on which constructor is used.
  • This implementation not synchronized provides guaranteed log(n) time cost for the basic operations (add, remove and contains).

public class TreeSet<E>
extends AbstractSet<E>
implements SortedSet<E>, Cloneable, Serializable

To prevent unsynchronized access to the Set.: SortedSet s = Collections.synchronizedSortedSet(new TreeSet(..));


Below is a TreeSet Example showing how collections are manipulated using a TreeSet

import java.util.Set;
import java.util.TreeSet;
import java.util.Iterator;

public class TreeSetExample {

	public static void doTreeSetExample() {
	public static void main(String[] args) {
		Set treeSet = new TreeSet();
		// the treeset stores Integer objects into the TreeSet
		for (int i = 0; i &lt; 5; i++) {
			treeSet.add(new Integer(i));
		// Since its a Integer Object Set adding any other elements in the Same
		// set will produce a
		// ClassCastException exception at runtime.
		// treeSet.add("a string");
		System.out.print("The elements of the TreeSet are : ");
		Iterator i = treeSet.iterator();
		while (i.hasNext()) {
			System.out.print( + "\t");


The elements of the TreeSet are : 0 1 2 3 4


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