Why can't I do assignment outside a method?

Question

If I try to assign a value to a variable in a class, but outside a method I get an error.

class one{
 Integer b;
 b=Integer.valueOf(2);
}

b

Answer 1

Because the assignments are statements and statements are allowed only inside blocks of code(methods, constructors, static initializers, etc.)

Outside of these only declarations are allowed.

This :

  class one{
        Integer b=Integer.valueOf(2);
  }

is a declaration with an initializer. That's why is accepted