Java ArrayList addAll(Collection c) Method example

In this tutorial we will see the usage of addAll() method of java.util.ArrayList class. This method is used for adding all the elements of a list to the another list.

public boolean addAll(Collection c)

It adds all the elements of specified Collection c to the current list.

Example

In this example we are adding all the elements of an arraylist to another arraylist by using addAll() method.

package beginnersbook.com;
import java.util.ArrayList;
public class ExampleOfaddAll {
   public static void main(String[] args) { 
        // ArrayList1 of String type
        ArrayList<String> al = new ArrayList<String>();
        al.add("Hi");
        al.add("hello");
        al.add("String");
        al.add("Test");
        System.out.println("ArrayList1 before addAll:"+al);

        //ArrayList2 of String Type
        ArrayList<String> al2 = new ArrayList<String>();
        al2.add("Text1");
        al2.add("Text2");
        al2.add("Text3");
        al2.add("Text4");

        //Adding ArrayList2 into ArrayList1
        al.addAll(al2);
        System.out.println("ArrayList1 after addAll:"+al);
   }
}

Output:

ArrayList1 before addAll:[Hi, hello, String, Test]
ArrayList1 after addAll:[Hi, hello, String, Test, Text1, Text2, Text3, Text4]

Reference:

http://docs.oracle.com/javase/6/docs/api/java/util/ArrayList.html#addAll(java.util.Collection)