darttype-conversionnullablenon-nullable

Why does `toString()` method on a null object in Dart not throw an exception?

I have the following code snippet in Dart:

void main(List<String> args){
 String? test1 = null;
 String test2 = test1.toString();
 print(test1);
 print(test2);
}

I expected the second print() statement to output an empty string because test2 is declared as a non-nullable String. However, it outputs “null” instead. Can someone explain why this is happening?

Thank you.

Solution

  • Because null is still an instance. Sole instance of class Null and it has toString() method implemented. See here for details: Null class