Variable-sized Array Initialization in Java

Question

I have an array of integers in Java that is initialized as follows:

public int MyNumbers[] = {0,0,0,0};

I would like to, however, initialize the array to a variable-length number of zeroes.

private int number_of_elements = 4;
public int MyNumbers[] = {0} * number_of_elements; // ????

I am clueless how to do this being new to Java coming from C. Any suggestions?

EDIT

I know I could use a for loop, but I hoping there was a simple way to do it.

Answer 1

int[] MyNumbers = new int[number_of_elements];

Answer 2

int[] myNumbers = new int[size];
Arrays.fill(myNumbers, 0);

see http://java.sun.com/j2se/1.5.0/docs/api/java/util/Arrays.html

Answer 3

Alternatively you could use ArrayList so that you don't need to worry about the size beforehand. It will dynamically expand the internal array whenever needed.

List<Integer> numbers = new ArrayList<Integer>();
numbers.add(0);
numbers.add(2);
// ...

Here's a tutorial to learn more about the Collections API, which ArrayList is part of.

Answer 4

int[] MyNumbers = new int[number_of_elements];

Since this is an array of int the array elements will get the default value for int's in Java of 0 automatically.

If this were an array of Integer objects then you would have to fill array after creating it as the default value for an object reference is null. To set default values in an Object array you can do the following:

Integer[] MyNumbers = new Integer[number_of_elements];
java.util.Arrays.fill(MyNumbers, new Integer(0));

The same technique could of course be used to initialize the int array to values other than zero like so:

int[] MyNumbers = new int[number_of_elements];
java.util.Arrays.fill(MyNumbers, 1);