[java] make arrayList.toArray() return more specific types

So, normally ArrayList.toArray() would return a type of Object[]....but supposed it's an Arraylist of object Custom, how do I make toArray() to return a type of Custom[] rather than Object[]?

This question is related to java arrays object types arraylist

The answer is

Like this:

List<String> list = new ArrayList<String>();

String[] a = list.toArray(new String[0]);

Before Java6 it was recommended to write:

String[] a = list.toArray(new String[list.size()]);

because the internal implementation would realloc a properly sized array anyway so you were better doing it upfront. Since Java6 the empty array is preferred, see .toArray(new MyClass[0]) or .toArray(new MyClass[myList.size()])?

If your list is not properly typed you need to do a cast before calling toArray. Like this:

    List l = new ArrayList<String>();

    String[] a = ((List<String>)l).toArray(new String[l.size()]);

It doesn't really need to return Object[], for example:-

    List<Custom> list = new ArrayList<Custom>();
    list.add(new Custom(1));
    list.add(new Custom(2));

    Custom[] customs = new Custom[list.size()];

    for (Custom custom : customs) {

Here's my Custom class:-

public class Custom {
    private int i;

    public Custom(int i) {
        this.i = i;

    public String toString() {
        return String.valueOf(i);

A shorter version of converting List to Array of specific type (for example Long):

Long[] myArray = myList.toArray(Long[]::new);

I got the answer...this seems to be working perfectly fine

public int[] test ( int[]b )
    ArrayList<Integer> l = new ArrayList<Integer>();
    Object[] returnArrayObject = l.toArray();
    int returnArray[] = new int[returnArrayObject.length];
    for (int i = 0; i < returnArrayObject.length; i++){
         returnArray[i] = (Integer)  returnArrayObject[i];

    return returnArray;

 public static <E> E[] arrayListToTypedArray(List<E> list) {

    if (list == null) {
      return null;
    int noItems = list.size();
    if (noItems == 0) {
      return null;

    E[] listAsTypedArray;
    E typeHelper = list.get(0);

    try {
      Object o = Array.newInstance(typeHelper.getClass(), noItems);
      listAsTypedArray = (E[]) o;
      for (int i = 0; i < noItems; i++) {
        Array.set(listAsTypedArray, i, list.get(i));
    } catch (Exception e) {
      return null;

    return listAsTypedArray;

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