Inheritance and Interfaces - Building Java Programs: A Back to Basics Approach - page 581

A

method1
method2
toString

B C

method2 method1

toString

D

method2

Figure 9.2 Hierarchy of classes A, B, C, and D

When someone calls method1 on an A object, the resulting output is " A 1 " . When
someone calls method2 on an A object, the resulting output is " A 2 " . When someone
prints an A object with toString , the resulting output is " A " . We can fill in the first
column of our table as shown in Table 9.3.

Table 9.3 Method Output for Class A

A

toString A

method1 A 1

method2 A 2

The next layer in the hierarchy is the B class, which inherits all the behavior from
A , except that it overrides the method2 output to be " B 2 " . That means you can fill in
the B output on your table identically to the A output, except that you replace " A 2 "
with " B 2 " . Table 9.4 shows the table so far.

Table 9.4 Method Output for Classes A and B

A B

toString A A

method1 A 1 A 1

method2 A 2 B 2

The C class also inherits all the behavior from A , but it overrides the method1 out-
put to be " C 1 " and it overrides the toString method to return " C " . Thus, the C out-