Inheritance and Interfaces - Building Java Programs: A Back to Basics Approach - page 582

put in the table will have the same second line as the A output, but we replace " A 1 "
with " C 1 " and " A " with " C " . Table 9.5 shows the updated table.

Table 9.5 Method Output for Classes A , B , and C

A B C

toString A A C

method1 A 1 A 1 C 1

method2 A 2 B 2 A 2

The D class inherits all the behavior from C , except that it overrides the method2
output to say " D 2 " . The final output data are shown in Table 9.6.

Table 9.6 Method Output for Classes A , B , C , and D

A B C D

toString A A C C

method1 A 1 A 1 C 1 C 1

method2 A 2 B 2 A 2 D 2

Once you've created your table, you can find the output of the client code. The array
contains an A object, a B object, a C object, and a D object. For each of these it prints the
toString output, then calls method1 , then calls method2 , then prints a blank line.
When a method gets called on an object, you can look up the output of that method for
that type in the table. The following is the complete output for the exercise:

A
A 1
A 2

A
A 1
B 2

C
C 1
A 2

C
C 1
D 2

Interpreting Complex Calls
In a more complicated version of the previous inheritance exercise, a class's methods
might call each other or interact with the superclass. Consider the following classes.