More about inheritance - Objects First with Java: A Practical Introduction Using BlueJ - page 325

Exercise 9.14 In the same situation as before (class Student , no toString method), will
the following lines compile? Why?
Student st = new Student();
System.out.println(st);
Exercise 9.15 Assume that your class Student overrides toString so that it returns the
student's name. You now have a list of students. Will the following code compile? If not, why
not? If yes, what will it print? Explain in detail what happens.
for(Object st : myList) {
System.out.println(st);
}
Exercise 9.16 Write a few lines of code that result in a situation where a variable x has the
static type T and the dynamic type D .