Test 3

Test 3 Name _Llave__ /100

1. (7) Rewrite the following class definition to remove duplication.

public class One
{
private String S;
private int I;

   public One (String theS, int theI)
   {
      S = theS;
      I = theI;
   }

   public void a ()
   {
      I = S.indexOf(“X”);
      S = S.subString(I, I+4);
      System.out.println( I );
   }

   public void b ()
   {
      I = S.indexOf(“X”);
      S = S.subString(I, I+4);
      System.out.println( S );
   }
}

public class One
{
private String S;
private int I;

   public One (String theS, int theI)
   {
      S = theS;
      I = theI;
   }

   public void ab ()
   {
      I = S.indexOf(“X”);
      S = S.subString(I, I+4);
   }

   public void a ()
   {
      ab();
      System.out.println( I );
   }

   public void b ()
   {
      ab();
      System.out.println( S );
   }
}

2. (8) Eliminate the explicit coupling between the A2 and B2 classes.

public class A2 {
private String A;
private B2 ab;

public A2()
{
    ab = new B2();
    ab.B = "white";
    A = ab.B;
}
}

public class A2 {
private String A;
private B2 ab;

public A2()
{
    ab = new B2();
    ab.setB ("white");
    A = ab.getB();
}
}

public class B2 {
public String B;

public B2()
{
B = "red";
}
}

public class B2 {
private String B;

public B2()
{
B = "red";
}

public void setB(String b)
{
B=b;
}

public String getB()
{

return B;

}
}

3. (5) Give the inheritance hierarchy diagram for the following:

class A extends Object { }
class B extends A { }
class C extends B { }
class D extends A { }
class E extends C { }
class F extends B { }
class G extends D { }
class H extends E { }

4. (10) Use inheritance to remove duplication. The resulting classes A and B should still behave equivalently.

public class A
{
private String S;
private int I;

  public A (String aS, int aI)
  {
    S = aS;
    I = aI;
  }

  public void ap ()
  {
    I = S.indexOf(“X”);
    S = S.subString(I, I+4);
  }

  public void print ()
  {
    System.out.println( S );
  }
}

public class B
{
private String S;
private int I;

   public B (String theS, int theI)
   {
      S = theS;
      I = theI;
   }

   public void bp ()
   {
      I = S.indexOf(“X”);
      S = S.subString(I, I+4);
   }

  public void print ()
  {
    System.out.println( I );
  }
}

public class A
{
private String S;
private int I;

  public A (String aS, int aI)
  {
    S = aS;
    I = aI;
  }

  public void ap ()
  {
    I = S.indexOf(“X”);
    S = S.subString(I, I+4);
  }

  public void print ()
  {
    System.out.println( S );
  }

public int getI()
{
return I;
}
}

public class B extends A
{
private String S;
private int I;

   public B (String theS, int theI)
   {
      super(theS, theI );
   }

   public void bp ()
   {
      ap();
   }

  public void print ()
  {
    System.out.println( getI() );
  }
}

public class C
{
private String S;
private int I;

  public C (String aS, int aI)
  {
    S = aS;
    I = aI;
  }

  public void cp ()
  {
    I = S.indexOf(“X”);
    S = S.subString(I, I+4);
  }

public int getI()
{
return I;
}

public int getS()
{
return S;
}
}

public class A extends C
{
  public A (String aS, int aI)
  {
    super( aS, aI);
  }

  public void ap ()
  {
    cp();
  }

  public void print ()
  {
    System.out.println( getS() );
  }
}

public class B extends C
{
public B (String theS, int theI)
   {
      super(theS, theI );
   }

   public void bp ()
   {
      cp();
   }

  public void print ()
  {
    System.out.println( getI() );
  }
}

5. (20) Indicate syntactically invalid statements (i.e. errors detected by the compiler). Trace the line numbers executed for valid statements.

a. TicketMachine tm = new TicketMachine( 50 ); _____6-11________

b. BusTM btm = new BusTM( 50, “A”, “X Y Z” ); ____26-28, 6-11, 29-31____

c. tm.insertMoney( 100 ); _____12-15______

d. btm.insertMoney( 100 ); _____12-15______

e. tm.printStops( ); ______invalid ____

f. btm.printStops( ); _____32-36 _____

g. tm.printTicket( ); _____16-21______

h. btm.printTicket( ); _____37-40, 16-21, 41_

i. tm = btm; _____valid_____

j. btm = tm; _____invalid____

6. (12) True or False. Indicate syntactically valid statements. For valid statements, indicate if an error occurs when executed.

public class Six
{
   private ArrayList <TicketMachine> aL;
   private TicketMachine tm;
   private BusTM btm;

   public Six ()
   {
      aL = new ArrayList<TicketMachine>();
      aL.add(new TicketMachine( 50 ) );
      aL.add(new BusTM( 50, “A”, “X Y Z” ) );
                                                                         Valid           Execution
                                                                   Syntax           Error

a. tm = aL.get( 0 ); _T__ _No__

b. btm = aL.get( 1 ); _T__ _No__

c. tm = aL.get( 0 ); _T__ _No__

d. tm = aL.get( 1 ); _T__ _No__

e. btm = aL.get( 0 ); _T__ _Yes__

f. btm = aL.get( 1 ); _T__ _No__

7. (15) Give the output produced, if any, when the following is executed.

public class Seven
{
private TicketMachine tm;
private BusTM btm;

   public Seven ()
   {
          tm = new TicketMachine( 50 ) ;
          btm = new BusTM( 50, “A”, “X Y Z” ) ;

a. tm.printTicket(); _________# 50_________________

b. btm.printTicket(); _________# Bus A
________ # 50______

c. btm.printStops(); ________ # A
________# Stops X Y Z_____

d. tm = btm; ________________________________

e. tm.printTicket(); _________# Bus A
________ # 50______

8. (23) Complete the definitions for the BusTerminal class.

a. Define an ArrayList field of type BusTM.

b. Define a BusTerminal constructor of no parameters. The constructor initializes the ArrayList field and adds 3 BusTM objects to the ArrayList field. Chose appropriate parameters for constructing BusTM objects.

c. Define a method that calls the printStops() method on all BusTM objects of the ArrayList.

d. Define a method getAllNames() that returns the concatenation of the name field of all BusTM objects in the ArrayList.

e. Define a method lowestPrice() that returns the lowest value of the price field of all BusTM objects in the ArrayList.

public class BusTerminal {

// a.
private ArrayList <BusTM> al;

// b.

public BusTerminal() {

al = new ArrayList <BusTM>();

al.add( new BusTerminal(100, "Red Line", "34th Elm Stadium") );

al.add( new BusTerminal(200, "Blue Line", "28th Oak IUS") );

al.add( new BusTerminal(150, "Pink Line", "6th YMCA Bono") );

}

// c.

public void printAllStops() {

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

al.get(i).printStops();

}

// d.

public String getAllNames() {

String result = "";

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

result = result + al.get(i).getName();

return result;

}

// e.

public int lowestPrice() {

int lowest = al.get(0).getPrice();

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

if( al.get( i ).getPrice() < lowest )

lowest = al.get( i ).getPrince();

}

1. public class TicketMachine

2. {

3. private int price;

4. private int balance;

5. private int total;

6. public TicketMachine(int ticketCost)

7. {

8. price = ticketCost;

9. balance = 0;

10. total = 0;

11. }

12. public void insertMoney(int amount)

13. {

14. balance += amount;

15. }

16. public void printTicket()

17. {

18. System.out.println(“# “ + price );

19. total += balance;

20. balance = 0;

21. }

22. public int getPrice()

23. {

24. return price;

25. }

26. }

23. public class BusTM extends TicketMachine

24. {

25. private String name, stops;

26. public BusTM( int theCost, String theName,
String theStops )

27. {

28. super( theCost );

29. name = theName;

30. stops = theStops;

31. }

32. public void printStops()

33. {

34. System.out.println("# Bus " + name );

35. System.out.println("# Stops " + stops );

36. }

37. public void printTicket()

38. {

39. System.out.println("# Bus " + name );

40. super.printTicket();

41. }

42. public String getName()

43. {

44. return name;

45. }

46. }

Test 3 Name ___Llave______ __/100

Test 3 Name _Llave__ /100