Java: Declaring a multidimensional array without specifying the size of the array ( eg. new int[10][] )

Question

I\'ve been trying to figure out what exactly is happening here. I\'m just trying to figure out what the 2 lines are doing that I\'ve commented on below. I found this program

Answer 1

The first line makes an array of int arrays. There are 10 slots for int arrays created.

The third line creates a new int array and puts it in one of the slots you made at first. The new int array has r+1 spaces for ints in it.

So, the int array in position 0 will have 1 slot for an int. The int array in position 1 will have 2 slots for an int. The overall shape will be:

[
    [0],
    [0,0],
    [0,0,0],
    ...,
    [0,0,0,0,0,0,0,0,0,0]
]

which is hinted at with the variable name tri (it looks like a triangle)