This method appends all of the elements in the specified collection to the end of this list, in the order that they are returned by the specified collection’s iterator.
Syntax:
boolean addAll(Collection c)
Parameters: This function has a single parameter, i.e, Collection c, whose elements are to be appended to the list.
Returns: It returns true if the elements of specified list is appended and list changes.
Below programs show the implementation of this method.
Program 1:
// Java code to show the implementation of// addAll method in list interfaceimport java.util.*;public class GfG {      // Driver code    public static void main(String[] args)    {          // Initializing a list of type arraylist        List<Integer> l = new ArrayList<>();        l.add(10);        l.add(15);        l.add(20);        System.out.println(l);          // Initializing a collection to be appended to list        ArrayList<Integer> arr = new ArrayList<Integer>();        arr.add(100);        arr.add(200);        arr.add(300);        System.out.println(arr);          l.addAll(arr);          System.out.println(l);    }} |
Output:
[10, 15, 20] [100, 200, 300] [10, 15, 20, 100, 200, 300]
Program 2: Below is the code to show implementation of list.addAll() using Linkedlist.
// Java code to show the implementation of// addAll method in list interfaceimport java.util.*;public class GfG {      // Driver code    public static void main(String[] args)    {          // Initializing a list of type Linkedlist        List<Integer> l = new LinkedList<>();        l.add(10);        l.add(15);        l.add(20);        System.out.println(l);          // Initializing a collection to be appended to list        ArrayList<Integer> arr = new ArrayList<Integer>();        arr.add(100);        arr.add(200);        arr.add(300);        System.out.println(arr);          l.addAll(arr);          System.out.println(l);    }} |
Output:
[10, 15, 20] [100, 200, 300] [10, 15, 20, 100, 200, 300]
Reference:
Oracle Docs
