Java Set addAll() Method With Examples

Syntax :

boolean addAll(Collection C)

Parameters: Given parameter C is a collection of any type in java that is to be added to the Set.

Return Value: Its returns true if it successfully added the elements of the collection C to this Set otherwise it returns False.

Now we will discuss java.util.Set.addAll() method with examples below .

Example 1 : Java Set addall() Method Example – Append TreeSet

In this example , Set.addAll() method added element of TreeSet to Set . We will we append element of TreeSet to Set Using addAll() method of Set.

import java.util.Set;
import java.util.TreeSet;

public class SetAddall {

	public static void main(String[] args) {

		Set<String> Set = new TreeSet<String>();
		Set.add("Java");
		Set.add("Vogue");
		Set.add("Welcomes");

		// print Set Elements 
		System.out.println("Set Elements : " + Set);

		TreeSet<String> treeSet = new TreeSet<String>();

		treeSet.add("You");
		treeSet.add("Thanks");

		// print treeSet
		System.out.println("TreeSet elements : " + treeSet);

		/*
		 * Adds all of the elements in the specified collection to Set
		 * collection
		 */

		Set.addAll(treeSet);

		System.out.println("After addAll() Set elements : " + Set);

	}

}

Output:

Set Elements : [Java, Vogue, Welcomes]
TreeSet elements : [Thanks, You]
After addAll() Set elements : [Java, Thanks, Vogue, Welcomes, You]

Example 2 : Java Set addall() Method Example – Add List to Set

import java.util.ArrayList;
import java.util.List;
import java.util.Set;
import java.util.TreeSet;

public class SetAddall1 {

	public static void main(String[] args) {
		Set<String> Set = new TreeSet<String>();
		Set.add("Java");
		Set.add("Vogue");
		Set.add("Welcomes");

		// print Set Elements
		System.out.println("Set elements : " + Set);

		List<String> list = new ArrayList<String>();

		list.add("You");
		list.add("Thanks");

		// print list element
		System.out.println("List elements : " + list);

		/*
		 * Adds all of the elements in the specified collection to Set
		 * collection
		 */

		Set.addAll(list);

		System.out.println("After addAll() Set elements : " + Set);

	}

}

Set elements : [Java, Vogue, Welcomes]
List elements : [You, Thanks]
After addAll() Set elements : [Java, Thanks, Vogue, Welcomes, You]