How to find Union of Two Sets in Java - Step by Step Examples

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How to find Union of Two Sets in Java ?

Answer

In Java, you can find the union of two sets using the addAll() method or the Stream API.

✐ Examples

1 Find Union of Two Sets using addAll() Method

In this example,

We create two sets named set1 and set2.
We use the addAll() method of set1 to add all elements of set2 to it.

Java Program

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

public class Main {
    public static void main(String[] args) {
        Set<Integer> set1 = new HashSet<>(Set.of(1, 2, 3));
        Set<Integer> set2 = new HashSet<>(Set.of(3, 4, 5));
        set1.addAll(set2);
        System.out.println("Union of set1 and set2: " + set1);
    }
}

Output

Union of set1 and set2: [1, 2, 3, 4, 5]

2 Find Union of Two Sets using Stream API

In this example,

We create two sets named set1 and set2.
We use the Stream API to create a stream from set2, filter elements not present in set1, and collect them into a new set.

Java Program

import java.util.HashSet;
import java.util.Set;
import java.util.stream.Collectors;

public class Main {
    public static void main(String[] args) {
        Set<Integer> set1 = new HashSet<>(Set.of(1, 2, 3));
        Set<Integer> set2 = new HashSet<>(Set.of(3, 4, 5));
        Set<Integer> unionSet = set2.stream()
                                  .filter(element -> !set1.contains(element))
                                  .collect(Collectors.toSet());
        set1.addAll(unionSet);
        System.out.println("Union of set1 and set2: " + set1);
    }
}

Output

Union of set1 and set2: [1, 2, 3, 4, 5]

Summary

In this tutorial, we learned How to find Union of Two Sets in Java language with well detailed examples.

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How to find Union of Two Sets in Java - Step by Step Examples

How to find Union of Two Sets in Java ?

Answer

✐ Examples

1 Find Union of Two Sets using addAll() Method

Java Program

Output

2 Find Union of Two Sets using Stream API

Java Program

Output

Summary

More Java Sets Tutorials