Convert List of Array into single Array

Question

How to convert List of arrays into a single array in Java. Is there any predefined function to use?

Below is the list of arrays, I want to iterate and keep all values in a single array.

List<Integer[]> integerArrayList = new ArrayList<Integer[]>();

Integer[] resultArray = {};

Is there efficient way to implement?

Answer 1

Java 8's stream make this pretty easy:

Integer[] resultArray = 
    integerArrayList.stream().flatMap(Arrays::stream).toArray(Integer[]::new);