HashSet containsAll() method in Java with Example
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( "Beginner" ); set.add( "for" ); set.add( "Beginner" ); 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( "Beginner" ); set2.add( "for" ); set2.add( "Beginner" ); 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: [Beginner, for, 20, 10] HashSet 2: [Beginner, 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( "Beginner" ); set.add( "for" ); set.add( "Beginner" ); // 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: [Beginner, for] HashSet 2: [20, 10] Does set 1 contains set 2: false
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