Convert ArrayList to Array in Java

An ArrayList provides two methods to convert it into Array.

Way #1

Object[] toArray()

Returns an array containing all of the elements in this list in proper sequence (from first to last element).

Way #2

<T> T[] toArray(T[] a)

Returns an array containing all of the elements in this list in proper sequence (from first to last element); the runtime type of the returned array is that of the specified array. If the list fits in the specified array, it is returned therein. Otherwise, a new array is allocated with the runtime type of the specified array and the size of this list.

Type Parameter

• T − The runtime type of the array to contain the collection.

Parameters

• a − The array into which the elements of this list are to be stored, if it is big enough; otherwise, a new array of the same runtime type is allocated for this purpose.

Returns

An array containing the elements of this list.

Throws

• ArrayStoreException − If the runtime type of the specified array is not a supertype of the runtime type of every element in this list.

• NullPointerException − If the specified array is null.

Example

Following is the example showing the usage of toArray() methods −

package com.tutorialspoint;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

public class CollectionsDemo {
   public static void main(String[] args) {
      List<String> list = new ArrayList<>(Arrays.asList("A","B","C", "D"));
      System.out.println("List: " + list);
      Object[] items = list.toArray();
      for (Object object : items) {
         System.out.print(object + " ");
      }
      System.out.println();
      String[] characters = list.toArray(new String[list.size()]);
      for (String string : characters) {
         System.out.print(string + " ");
      }
   }
}

Output

This will produce the following result −

List: [A, B, C, D]
A B C D
A B C D