Java TreeSet - contains() Method

The java.util.TreeSet.contains() method is used to check whether the set contains the specified element or not. The method returns true if the set contains the specified element, else returns false.

Syntax

public boolean contains(Object obj)

Parameters

Return Value

Returns true if this set contains the specified element.

Exception

• Throws ClassCastException, if the specified object cannot be compared with the elements currently in the set.
• Throws NullPointerException, if the specified element is null and this set uses natural ordering, or its comparator does not permit null elements.

Example:

In the example below, the java.util.TreeSet.contains() method is used to check the presence of specified element in the given set.

import java.util.*;

public class MyClass {
  public static void main(String[] args) {
    //creating treeset
    TreeSet<Integer> MySet = new TreeSet<Integer>();

    //populating the set
    MySet.add(10);
    MySet.add(20);
    MySet.add(30);
    MySet.add(40);

    //checking the presence of elements
    for(int i = 5; i <= 20; i += 5) {
      if(MySet.contains(i))
        System.out.println(i +" is present in MySet.");
      else
        System.out.println(i +" is NOT present in MySet.");
    }       
  }
}

The output of the above code will be:

5 is NOT present in MySet.
10 is present in MySet.
15 is NOT present in MySet.
20 is present in MySet.