Given a Collection with some values, the task is to add all the items of this Collection to an ArrayList in Java.
Illustrations:
Input: Collection = [1, 2, 3] Output: ArrayList = [1, 2, 3]
Input: Collection = [GFG, Geek, GeeksForGeeks] Output: ArrayList = [GFG, Geek, GeeksForGeeks]
Approach:
- Get the Collection whose items are to be added into the ArrayList
- Create an ArrayList
- Add all the items of Collection into this ArrayList using ArrayList.addAll() method
- ArrayList with all the items of Collections have been created.
Example
Java
// Java Program to Add All Items from a collection // to an ArrayList // Importing required classes import java.io.*;
import java.util.*;
import java.util.stream.*;
// Main class class GFG {
// Method 1
// To add all items from a collection
// to an ArrayList
public static <T> ArrayList<T>
createArrayList(List<T> collection)
{
// Creating an ArrayList
ArrayList<T> list = new ArrayList<T>();
// Adding all the items of Collection
// into this ArrayList
list.addAll(collection);
return list;
}
// Method 2
// Main driver method
public static void main(String[] args)
{
// Getting array elements as list
// and storing in a List object
List<Integer> collection1 = Arrays.asList( 1 , 2 , 3 );
// Printing elements in above List object
System.out.println( "ArrayList with all "
+ "elements of collection "
+ collection1 + ": "
+ createArrayList(collection1));
// Again creating another List class object
List<String> collection2 = Arrays.asList(
"GFG" , "Geeks" , "GeeksForGeeks" );
// Printing elements in above List object
System.out.println( "ArrayList with all"
+ " elements of collection "
+ collection2 + ": "
+ createArrayList(collection2));
}
} |
Output
ArrayList with all elements of collection [1, 2, 3]: [1, 2, 3] ArrayList with all elements of collection [GFG, Geeks, GeeksForGeeks]: [GFG, Geeks, GeeksForGeeks]