Java Reference
In-Depth Information
Listing 16-3.
Testing the Manager Class
// SimplestInheritanceTest.java
package com.jdojo.inheritance;
public class SimplestInheritanceTest {
public static void main(String[] args) {
// Create an object of the Manager class
Manager mgr = new Manager();
// Set the name of the manager
mgr.setName("Leslie Zanders");
// Get the name of the manager
String mgrName = mgr.getName();
// Display the manager name
System.out.println("Manager Name: " + mgrName);
}
}
Manager Name: Leslie Zanders
Even if you did not write any code for the
Manager
class, it works the same as the
Employee
class, because it
inherits from the
Employee
class. You create a manager object by using the
Manager
class's constructor.
Manager mgr = new Manager();
After the manager object is created, the code looks similar to the one you used for dealing with an
Employee
object. You used the
setName()
and
getName()
methods with the manager object.
mgr.setName("Leslie Zanders");
String mgrName = mgr.getName();
Note that the
Manager
class does not declare the
setName()
and
getName()
methods. Neither does it declare the
name
instance variable. However, it appears that all of them have been declared inside the
Manager
class, because
it uses the “
extends Employee
” clause in its declaration. When a class inherits from another class, it inherits its
superclass members (instance variables, methods, etc.). There are many rules that govern inheritance. I will discuss
those rules in details one-by-one later in this chapter.
Object Class is the Default Superclass
If a class does not specify a superclass using the keyword
extends
in its class declaration, it inherits from the
java.lang.Object
class. For example, the following two class declarations for class
P
are the same:
// #1 - "extends Object" is implicitly added for class P
public class P {
// Code for class P goes here
}
