How to create a Set of Sets in Java - Step by Step Examples

How to create a Set of Sets in Java ?

Answer

To create a Set of Sets in Java, you can use the HashSet class to create individual sets and then nest them within another set using the same class.

✐ Examples

1 Creating a Set of Sets of Integers

In this example,

First, we create three individual sets of integers named set1, set2, and set3 using the HashSet class. We add the elements 1, 2, 3 to set1, 4, 5, 6 to set2, and 7, 8, 9 to set3.
Next, we create a set of sets named setOfSets using the HashSet class, and we add set1, set2, and set3 to this set. This nests the three sets within a single set.
We then use an enhanced for loop to iterate over each set within setOfSets. Within the loop, we print each individual set to the standard output.

Java Program

import java.util.HashSet;
import java.util.Set;

public class Main {
    public static void main(String[] args) {
        Set<Integer> set1 = new HashSet<>();
        set1.add(1);
        set1.add(2);
        set1.add(3);

        Set<Integer> set2 = new HashSet<>();
        set2.add(4);
        set2.add(5);
        set2.add(6);

        Set<Integer> set3 = new HashSet<>();
        set3.add(7);
        set3.add(8);
        set3.add(9);

        Set<Set<Integer>> setOfSets = new HashSet<>();
        setOfSets.add(set1);
        setOfSets.add(set2);
        setOfSets.add(set3);

        for (Set<Integer> set : setOfSets) {
            System.out.println(set);
        }
    }
}

Output

Output:
[1, 2, 3]
[4, 5, 6]
[7, 8, 9]

2 Creating a Set of Sets of Strings

In this example,

First, we create three individual sets of strings named setA, setB, and setC using the HashSet class. We add the elements "apple", "banana", "cherry" to setA, "dog", "elephant", "fox" to setB, and "grape", "honeydew", "kiwi" to setC.
Next, we create a set of sets named setOfStringSets using the HashSet class, and we add setA, setB, and setC to this set. This nests the three sets within a single set.
We then use an enhanced for loop to iterate over each set within setOfStringSets. Within the loop, we print each individual set to the standard output.

Java Program

import java.util.HashSet;
import java.util.Set;

public class Main {
    public static void main(String[] args) {
        Set<String> setA = new HashSet<>();
        setA.add("apple");
        setA.add("banana");
        setA.add("cherry");

        Set<String> setB = new HashSet<>();
        setB.add("dog");
        setB.add("elephant");
        setB.add("fox");

        Set<String> setC = new HashSet<>();
        setC.add("grape");
        setC.add("honeydew");
        setC.add("kiwi");

        Set<Set<String>> setOfStringSets = new HashSet<>();
        setOfStringSets.add(setA);
        setOfStringSets.add(setB);
        setOfStringSets.add(setC);

        for (Set<String> set : setOfStringSets) {
            System.out.println(set);
        }
    }
}

Output

Output:
[apple, banana, cherry]
[dog, elephant, fox]
[grape, honeydew, kiwi]

Summary

In this tutorial, we learned How to create a Set of Sets in Java language with well detailed examples.

◀ Previous Next ▶

Java Tutorials

Java How-Tos

How to create a Set of Sets in Java - Step by Step Examples

How to create a Set of Sets in Java ?

Answer

✐ Examples

1 Creating a Set of Sets of Integers

Java Program

Output

2 Creating a Set of Sets of Strings

Java Program

Output

Summary

More Java Sets Tutorials