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HashSet containsAll() method in Java with Example

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The containsAll() method of Java HashSet is used to check whether two sets contain the same elements or not. It takes one set as a parameter and returns True if all of the elements of this set is present in the other set.

Syntax:

public boolean containsAll(Collection C)

Parameters: The parameter C is a Collection. This parameter refers to the set whose elements occurrence is needed to be checked in this set.

Return Value: The method returns True if this set contains all the elements of other set otherwise it returns False.

Below programs illustrate the HashSet.containsAll() method:

Program 1:




// Java code to illustrate
// HashSet containsAll()
  
import java.util.*;
  
class HashSetDemo {
    public static void main(String args[])
    {
  
        // Creating an empty set
        HashSet<String>
            set = new HashSet<String>();
  
        // Use add() method to
        // add elements in the set
        set.add("Geeks");
        set.add("for");
        set.add("Geeks");
        set.add("10");
        set.add("20");
  
        // prints the set
        System.out.println("HashSet 1: "
                           + set);
  
        // Creating another empty set
        HashSet<String>
            set2 = new HashSet<String>();
  
        // Use add() method to
        // add elements in the set
        set2.add("Geeks");
        set2.add("for");
        set2.add("Geeks");
        set2.add("10");
        set2.add("20");
  
        // prints the set
        System.out.println("HashSet 2: "
                           + set2);
  
        // Check if the set
        // contains same elements
        System.out.println("\nDoes set 1 contains set 2: "
                           + set.containsAll(set2));
    }
}


Output:

HashSet 1: [Geeks, for, 20, 10]
HashSet 2: [Geeks, for, 20, 10]

Does set 1 contains set 2: true

Program 2:




// Java code to illustrate boolean containsAll()
  
import java.util.*;
  
class HashSetDemo {
    public static void main(String args[])
    {
  
        // Creating an empty set
        HashSet<String>
            set = new HashSet<String>();
  
        // Use add() method to
        // add elements in the set
        set.add("Geeks");
        set.add("for");
        set.add("Geeks");
  
        // prints the set
        System.out.println("HashSet 1: "
                           + set);
  
        // Creating another empty set
        HashSet<String>
            set2 = new HashSet<String>();
  
        // Use add() method to
        // add elements in the set
        set2.add("10");
        set2.add("20");
  
        // prints the set
        System.out.println("HashSet 2: "
                           + set2);
  
        // Check if the set
        // contains same elements
        System.out.println("\nDoes set 1 contains set 2: "
                           + set.containsAll(set2));
    }
}


Output:

HashSet 1: [Geeks, for]
HashSet 2: [20, 10]

Does set 1 contains set 2: false


Last Updated : 24 Dec, 2018
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