Testing and converting types

Everything in Dart is an object and has a type; an instance of a class descended from an object through a single inheritance chain, even null is of type Null. Type annotating a variable is not required in Dart, for example, contrary to Java. In this case, the variable is declared with var and is of type dynamic. Values sometimes have to be converted from one type to another. In order to avoid runtime type errors when the conversion fails, we can test if the value is of the type we want to cast it to before the conversion. For the code examples, refer to types.dart.

How to do it...

We can test and convert types with the help of the following steps:

1. We can test and show the type of an object, as shown in the following code:

   void main() {
     var p = new Person();
     p.name = "Joe";
   if (p is Person) {
        print('p is called ${p.name}');
        print('p is of type ${p.runtimeType}');                     } else {
      // p has value null and is of type Null
      print('p has...