Homework 8

1. Ch 9 Exercise 1

a) mySphere.displayStatistics() calls area() in Sphere and myBall.displayStatistics() calls area in Ball. Whenever a method is overridden in a derived class, objects of the derived class used the overridden method.

b) Sphere s1 = new Sphere();
Ball b1 = new Ball();

s1.displayStatistics(); //calls area() in Sphere because s1 refers to a Sphere object
s1 = b1;
s1.displayStatistics(); // calls area() in Ball because s1 refers to a Ball object
b1.displayStatistics(); // calls area() in Ball because b1 refers to a Ball object

2. Ch 9 Exercise 10 (Solution is for Person, Student and GraduateStudent instead of Employee, HourlyEmployee, and NonHourlyEmployee.
   
   

abstract class Person

{

private String _name;

abstract public int yearsExperience();

public Person(String name) {

_name = name;

}

public String getName() {

return _name;

}

public void setName(String name) {

_name= name;

}

}

class Student extends Person

{

private int _year;

public Student(String name, int year) {

super(name);

_year = year;

}

public int yearsExperience() {

return _year;

}

public void setYear(int year) {

_year = year;

}

}

class GraduateStudent extends Student

{

private String _thesisTitle;

public GraduateStudent(String name, int year, String thesisTitle) {

super(name, year);

_thesisTitle = thesisTitle;

}

public void setThesisTitle(String title) {

_thesisTitle = title;

}

public String getThesisTitle()

{

return _thesisTitle;

}

}

3. Ch 9 Programming Problem 1
   
   
   

// Note, jdk Interface List and class LinkedList are used instead of the

// book's ListInterface and ListReferenceBased.

import java.util.LinkedList;

import java.util.List;

public class SortedList implements SortedListInterface {

private List<Comparable> aList;

public SortedList() {

aList = new LinkedList();

}

public int size() {

return aList.size();

}

public boolean isEmpty() {

return aList.isEmpty();

}

public void removeAll() {

aList.clear();

}

public void sortedAdd(Comparable newItem) throws ListException {

for (int i = 0; i < aList.size(); i++) {

if (newItem.compareTo(aList.get(i)) <= 0) {

aList.add(i, newItem);

return;

}

}

aList.add(newItem);

}

public Comparable get (int index) throws IndexOutOfBoundsException {

return aList.get(index);

}

public int locateIndex(Comparable anItem) {

return aList.indexOf(anItem);

}

public void sortedRemove(Comparable anItem) throws ListException {

// Note, this is not the most efficient implementation because

// it iterates all the way through the list for an item that

// is not found

aList.remove(anItem);

}

public static void main(String[] args) {

SortedList list = new SortedList();

list.sortedAdd("Smith");

list.sortedAdd("Zacheral");

list.sortedAdd("Jones");

list.sortedAdd("Anthony");

list.sortedAdd("Baker");

list.sortedAdd("Osterman");

for (int i = 0; i < list.size(); i++) {

System.out.println(list.get(i));

}

}

}