Inheritance - Absolute Java - page 471

Self-Test Exercises (continued)
20. Redefi ne 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 defi nition 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. Redefi ne 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 defi ned 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 *,” earlier in this chapter.)
Although we did not discuss 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 defi nition of nextElement to add to the defi nition of
EnhancedStringTokenizer . This defi nition will override the defi nition of
nextElement in the class StringTokenizer . ( Hint : the defi nition is just like the
defi nition of nextToken except for fi xing the type of the string returned.)