How to convert List to int[] in Java? [duplicate]

Answer 1

The easiest way to do this is to make use of Apache Commons Lang. It has a handy ArrayUtils class that can do what you want. Use the toPrimitive method with the overload for an array of Integers.

List myList;
 ... assign and fill the list
int[] intArray = ArrayUtils.toPrimitive(myList.toArray(new Integer[myList.size()]));

This way you don't reinvent the wheel. Commons Lang has a great many useful things that Java left out. Above, I chose to create an Integer list of the right size. You can also use a 0-length static Integer array and let Java allocate an array of the right size:

static final Integer[] NO_INTS = new Integer[0];
   ....
int[] intArray2 = ArrayUtils.toPrimitive(myList.toArray(NO_INTS));