There's no such thing as multi-dimensional arrays in
Java. We have arrays of anything, including other arrays. But arrays are objects, so, in a seemingly two-dimensional situation, you actually have an array of objects (specifically, arrays). The default value of any object type variable/value is null.
Another way to put this is to point out that mArr2 is not a two-dimensional array of double, it's a single dimension array of pointers/references to arrays.
It's also worth mentioning that Arrays.toString does not behave the same as Arrays.deepToString.
Try these two changes (first just the first one, then add the second too)
1) add a second "dimension" value to your code like this:
Run it and see the output
2) Add another print statement:
Run it and see again.
Help any?