Inheritance - Java - page 457

Self-Test Exercises (continued)
20. Redefine the equals method of the class SalariedEmployee (Display 7.5) so that
it has a parameter of type Object and follows the other guidelines we gave for
an equals method. Assume the definition of the method equals for the class
Employee has been changed to be as in Display 7.10. (Remember, you should use
getClass() , not instanceof .)
21. Redefine the equals method of the class Date (Display 4.13) so that it has a
parameter of type Object and follows the other guidelines we gave for an equals
method. (Remember, you should use getClass() , not instanceof .)
22. What is the output produced by the following program? (The classes Employee
and HourlyEmployee were defined in this chapter.)
public class Test
{
public static void main(String[] args)
{
Employee object1 = new Employee();
Employee object2 = new HourlyEmployee();
if (object1.getClass( ) == object2.getClass( ))
System.out.println("Same class.");
else
System.out.println("Not the same class.");
}
}
23. (This exercise requires that you have covered the starred subsection “An
Enhanced StringTokenizer Class *.”)
Although we did not cover it when we covered the class StringTokenizer , the
class StringTokenizer has a method with the following heading:
public Object nextElement()
The method nextElement() returns the same string as the method nextToken() ,
but nextElement() returns it as something of type Object , as opposed to type
String . Give a suitable definition of nextElement to add to the definition of
EnhancedStringTokenizer . This definition will override the definition of
nextElement in the class StringTokenizer . ( Hint : the definition is just like the
definition of nextToken except for fixing the type of the string returned.)