Is it possible to have undefined array?

Answer 1

Yes, as ~swim~ said 😁

You can also have anonymous array (with no name)

for(var i: new int[]{2,8,6,9})
System.out.println(i);

Answer 2

Yes of course, in Javascript you can have array that contains undefined (undefined array)

ar = [, , ,];
for(let x of ar)
console.log(x);