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 classesimport java.io.*;import java.util.*;import java.util.stream.*;// Main classclass 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]