CollectionUtils union() Example in Java

By
Rakesh
-

The CollectonsUtils.union() method is used to get the union of two lists. Consider we have two lists list1 and list2, which have different elements.

package com.javatute;

import java.util.ArrayList;
import java.util.List;

import org.apache.commons.collections4.CollectionUtils;

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

		// Create first list
		List<String> list1 = new ArrayList<>();
		// add some element
		list1.add("John");
		list1.add("Mark");
		list1.add("Smith");
		list1.add("Twin");

		// create second list
		List<String> list2 = new ArrayList<>();
		// add some element
		list2.add("John");
		list2.add("Mark");
		list2.add("Smith");
		list2.add("Twin");
		list2.add("James");

		System.out.println(CollectionUtils.union(list1, list2));
	}
}

Output – [James, Smith, John, Mark, Twin]

Note – We need to add maven dependency in order to use CollectionUtils class.

<dependency>
    <groupId>org.apache.commons</groupId>
    <artifactId>commons-collections4</artifactId>
    <version>4.4</version>
</dependency>

That’s all about CollectionUtils union() Example in Java.

See CollectionUtils union() method docs.

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