 # Java Program to Calculate union of two sets

In this example, we will learn to calculate the union of two sets in Java.

To understand this example, you should have the knowledge of the following Java programming topics:

## Example 1: Calculate the union of two sets using addAll()

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

class Main {
public static void main(String[] args) {

// create the first set
Set<Integer> evenNumbers = new HashSet<>();
System.out.println("Set1: " + evenNumbers);

// create second set
Set<Integer> numbers = new HashSet<>();
System.out.println("Set2: " + numbers);

// Union of two sets
System.out.println("Union is: " + numbers);
}
}``````

Output

```Set1: [2, 4]
Set2: [1, 3]
Union is: [1, 2, 3, 4]```

In the above example, we have created two sets named evenNumbers and numbers. We have implemented the set using the `HashSet` class. Notice the line,

``numbers.addAll(evenNumbers);``

Here, we have used the `addAll()` method to get the union of two sets.

## Example 2: Get union of two sets using Guava Library

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

class Main {
public static void main(String[] args) {

// create the first set
Set<String> languages1 = new HashSet<>();
System.out.println("Programming Languages: " + languages1);

// create second set
Set<String> languages2 = new HashSet<>();
System.out.println("Human Language: " + languages2);

Set<String> unionSet = Sets.union(languages1, languages2);
System.out.println("Union is: " + unionSet);
}
}``````

Output

```Programming Languages: [Java, Python]
Human Languages: [English, Spanish]
Languages: [Java, Python, English, Spanish]```

In the above example, we have used the Guava library to get the union of two sets. In order to run this program, you need to implement Guava Library by adding it in your dependency.

Here, we have used the `union()` method of the Sets class present in the Guava library.