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Set containsAll() method in Java with Examples
  • Last Updated : 31 Dec, 2018

The containsAll() method of Java Set 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 Set.containsAll() method:



Program 1:




// Java code to illustrate
// Set containsAll()
  
import java.util.*;
  
class SetDemo {
    public static void main(String args[])
    {
  
        // Creating an empty set
        Set<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("Set 1: "
                           + set);
  
        // Creating another empty set
        Set<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("Set 2: "
                           + set2);
  
        // Check if the set
        // contains same elements
        System.out.println("\nDoes set 1 contains set 2?: "
                           + set.containsAll(set2));
    }
}


Output:

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

Does set 1 contains set 2?: true

Program 2:




// Java code to illustrate boolean containsAll()
  
import java.util.*;
  
class SetDemo {
    public static void main(String args[])
    {
  
        // Creating an empty set
        Set<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("Set 1: "
                           + set);
  
        // Creating another empty set
        Set<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("Set 2: "
                           + set2);
  
        // Check if the set
        // contains same elements
        System.out.println("\nDoes set 1 contains set 2: "
                           + set.containsAll(set2));
    }
}


Output:

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

Does set 1 contains set 2: false

Reference: https://docs.oracle.com/javase/7/docs/api/java/util/Set.html#containsAll(java.util.Collection)

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