How to add all elements to the given collection object?

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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]