Example 1: Check subset of a Set using HashSet class
import java.util.HashSet;
import java.util.Set;
class Main {
public static void main(String[] args) {
// create the first set
Set<Integer> numbers = new HashSet<>();
numbers.add(1);
numbers.add(2);
numbers.add(3);
numbers.add(4);
System.out.println("Numbers: " + numbers);
// create the second set
Set<Integer> primeNumbers = new HashSet<>();
primeNumbers.add(2);
primeNumbers.add(3);
System.out.println("Prime Numbers: " + primeNumbers);
// check if primeNumbers is a subset of numbers
boolean result = numbers.containsAll(primeNumbers);
System.out.println("Is Prime Numbers is subset of Numbers? " + result);
}
}
Output
Numbers: [1, 2, 3, 4] Prime Numbers: [2, 3] Is Prime Numbers is subset of Numbers? true
In the above example, we have created two sets named numbers and primeNumbers. We have implemented the set using the HashSet
class. Notice the line,
numbers.containsAll(primeNumbers);
Here, we have used the containsAll() method to check if primeNumbers is the subset of numbers.
Example 2: Check subset of a Set using TreeSet class
import java.util.TreeSet;
import java.util.Set;
class Main {
public static void main(String[] args) {
// create the first set
Set<String> languages = new TreeSet<>();
languages.add("Java");
languages.add("JavaScript");
languages.add("Python");
languages.add("CSS");
System.out.println("Programming Languages: " + languages);
// create the second set
Set<String> frontend = new TreeSet<>();
frontend.add("CSS");
frontend.add("JavaScript");
System.out.println("Frontend Languages: " + frontend);
// check if frontend is a subset of languages
boolean result = languages.containsAll(frontend);
System.out.println("Is frontend is subset of languages? " + result);
}
}
Output
Programming Languages: [CSS, Java, JavaScript, Python] Frontend Languages: [CSS, JavaScript] Is frontend is subset of languages? true
Here, we have implemented the set using the TreeSet
class.