Why is my cast List not matching?

Question

Simplified Question:

Starting with dynamic x = [a, b] where a and b are String.

The following cast fails, i.e. the print out is 'fail':

if(x is List<String>){
  print('pass');
} else{
  print('fail');
}

I think the above is the simplified version of my question, but in case you need more info, see below for more detailed version.

More Detailed Question (if needed)

I have a dynamic List that can be any number of levels deep. For example, it may start like this:

x = [a, [b, c, d], [e, [f, g, h], i]]

Where each letter above is a String. I'm looping through to unwrap it and can catch it when it gets to the final String by doing:

if(x is String) { ... } // Works!

But, when I try to catch it one level before becoming a String, List<String> it will never match. For example, the following doesn't work EVEN when the dynamic it is given is a List<String>:

if(x is List<String>) {...} // Doesn't work

Why isn't List<String> ever true?

More complete example:

x = [a, [b, c, d], [e, [f, g, h], i]]
for (var i = 0; i < x.length; i++) {
    if(x is List<String>){ ... } // Never works even if print(x) prints [b, c, d]
    else if(x is String){ ... } //Works!
    else { ... } // Works obviously
}

Answer 1

As you might declare b, c, and d as dynamic, Flutter considers as List<dynamic>, so you have to give typed List as following..

x = [a, <String>[b, c, d], [e, <String>[f, g, h], i]]

Or

You have to check with dynamic List

if (x is List) { ... }