Learning Java - What is "new String[0]"?

I came across some code as:

row.add( row.toArray( new String[0] ) );

But, what does "new String[0]" mean?

I found some good answers at the following (StackOverflow site):

• http://stackoverflow.com/questions/18136437/whats-the-use-of-new-string0-in-toarraynew-string0
• http://stackoverflow.com/questions/16459590/need-for-new-string0-in-the-set-toarray-method
• http://stackoverflow.com/questions/9753576/whats-the-meaning-of-char-zero-0-in-java

According to my code, since my "row" object is not a granddaddy Java type Object but a String type, I want to add a row of String type to the existing row(s). By telling the method .toArray() to return reference type of String and not Object, my row will add a new array of Strings. By passing '0' into the String array, we are declaring to return the type only.

Here's a combined answer taken from folk at StackOverflow:

It is the array into which the elements of the Set are to be stored, if it is big enough; otherwise, a new array of the same runtime type is allocated for this purpose.

So that, in this example, you get back a String[]. The one without any argument gives back to you an Object[].

See you have 2 versions of this method:

• Object[] toArray()
• <T> T[] toArray(T[] a)

By passing String[] array, you are using the generic version.

Object[] toArray(), returns an Object[] which cannot be cast to String[] or any other type array.

T[] toArray(T[] a) , returns an array containing all of the elements in this set; the runtime type of the returned array is that of the specified array. If the set fits in the specified array, it is returned therein. Otherwise, a new array is allocated with the runtime type of the specified array and the size of this set.