16.1: no project

Look at the code below. You have four classes (O, X, T and M) and a variable containing each of these.

   O o;
   X x;
   T t;
   M m;

The following assignments are all legal (assume they all compile):

   m = t;
   m = x;
   o = t;

The following assignments are all illegal (they cause comiler errors):

   o = m;
   o = x;
   x = o;

What can you say about the relationships of these classes? Draw a class digram showing the inheritance hierarchy. (Based on Barnes & Kolling ex 8.17)

16.2: DoME-v2 project

Create an object of class DVD in your project, and then invoke the toString method from the Object sub-menu in the object's popup menu. (Based on Barnes & Kolling ex 9.6)

16.3: DoME-v3 project

Include code 9.2 (page 267) in both classes CD and DVD. When run with appropriate data, the results printed should match fig 9.9 (page 272). (Based on Barnes & Kolling text)

16.4: DoME-v3 project

Re-order the statements in the CD and DVD print methods so that it prints details as shown in fig 9.10 (page 273). (Based on Barnes & Kolling ex 9.7)

16.5: no project

Assume you see the following lines of code:

   Device dev = new Printer();
   dev.getName();

16.6: no project

In the same situation as in the previous exercise, if both classes have an implementation of getName, which one will be executed? (Barnes & Kolling ex 9.13)

16.7: no project

Assume you write a class Student, which does not have a declared superclass. You do not write a toString method. Will the following lines of code compile? Why?

   Student st = new Student();
   System.out.println(st);