Is the Braces in the following statement means an open array?

Integer[] ints = list.toArray(new Integer[]{});

If I remove "{}" the compiler asks to fill in a dimension for the array. What do the two braces mean as a command?

It means you initialize the array with what is in between the braces. Ex:

new Integer[] { 1, 2, 3}

Makes an array with 1, 2 and 3. On the other hand:

new Integer[] {}

Just mean that you initialize an array without any values. So it is the same as new Integer[0].

This actually means empty array. The {} allow you to supply the elements of the array:

Integer[] ints = list.toArray(new Integer[]{1, 2, 3});

is equivalent to:

Integer[] ints = new Integer[3];
ints[0] = 1;
ints[1] = 2;
ints[2] = 3;

Check this link:

• http://download.oracle.com/javase/tutorial/java/nutsandbolts/arrays.html

for more information - go to Creating, Initializing, and Accessing an Array section.

Yes, an empty array. Just like Integer[0].