How to add all elements to the given collection object?

The java.util.Collections class consists exclusively of static methods that operate on or return collections. It contains polymorphic algorithms that operate on collections, “wrappers”, which return a new collection backed by a specified collection, and a few other odds and ends.

Collections.addAll() method adds all of the specified elements to the specified collection.
Syntax: public boolean addAll(Collection c)

Example

package com.w3schools;
 
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
 
public class Test {
	public static void main(String a[]) {
		List<String> list = new ArrayList<String>();
		list.add("vikas");
		list.add("ajay");
		list.add("amit");
		System.out.println("First list:" + list);
		Collections.addAll(list, "anil", "mahesh");
		System.out.println("After adding elements:" + list);
	}
}

Output

First list:[vikas, ajay, amit]
After adding elements:[vikas, ajay, amit, anil, mahesh]