How to convert List to Array in Java

Last updated on July 9, 2020 by Dan Nanni

Suppose you are maintaining a list of objects using List (i.e., List<Object>), and want to convert it into an array of objects (i.e., Object[]). How would you convert List to Array in Java?

To do that, you can in general take advantage of List.toArray(), which returns Object[], an array of all the elements in the list.

Here is a code example of converting List to Array with List.toArray().

List<String> strList = new ArrayList<String> ();
strList.add("apple");
strList.add("orange");
strList.add("mango");

String[] strArray = strList.toArray(new String[strList.size()]);

However, one caveat of this approach is that List.toArray() does not work with primitive object types such as int, float, etc.

In order to convert List of primitive types to a corresponding array, you can leverage ArrayUtils.toPrimitive(Object[] array), which converts an array of non-primitive Objects to primitives. ArrayUtils is available in Apache Commons Lang library.

Here is a code example of converting List<Integer> to int[] with ArrayUtils.toPrimitive().

import org.apache.commons.lang.ArrayUtils;

List<Integer> intList;
intList.add(1);
intList.add(5);
intList.add(7);

int[] intArray = ArrayUtils.toPrimitive(intList.toArray(new Integer[intList.size()]));

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