1. (10 pts) What is wrong with the following program? 1 public class MyClassA {
ID: 667104 • Letter: 1
Question
1. (10 pts) What is wrong with the following program?
1 public class MyClassA {
2 int v = 12;
3
4 public MyClassA (int pV) {
5 v = pV;
6 }
7
8 public static void main (String args []) {
9 MyClassA m = new MyClassA ();
10 } // end main
11 } // end class MyClassA
2. (10 pts) What is wrong with the following program?
1 public class MyClassB {
2 int v = 12;
3
4 public void MyClassB (int pV) {
5 v = pV;
6 }
7
8 public static void main (String args []) {
9 MyClassB m = new MyClassB (23);
10 } // end main
11 } // end class MyClassB
3. (10 pts) What is wrong with the following program? (updated 5/26, line 11)
1 public class MyClassD {
2 public static void main (String args []) {
3 MyClassC m = new MyClassC (23);
4 } // end main
5 } // end class MyClassD
6
7 public class MyClassC {
8 int v = 12;
9
10 public MyClassC (int pV) {
11 int v = pV;
12 }
13
14 } // end class MyClassC
4. (10 pts) What is wrong with the following program?
1 public class MyClassD {
2 public static void main (String args []) {
3 MyClassC m = new MyClassC (23);
4 } // end main
5 } // end class MyClassC
6
7 class MyClassC {
8 int v = 12;
9
10 private MyClassC (int pV) {
11 v = pV;
12 }
13
14 } // end class MyClassC
5. (10 pts) Given all the problems identified in problems 1 through 4, explain in detail why the following code works, ie, compiles without errors or warnings.
1 public class MyClassD {
2 public static void main (String args []) {
3 MyClassC m = new MyClassC (23, true);
4 } // end main
5 } // end class MyClassD
6
7 class MyClassC {
8 int v = 12;
9
10 public MyClassC (int x, boolean b) {
11 this (x);
12 }
13
14 private MyClassC (int pV) {
15 v = pV;
16 }
17
18 } // end class MyClassC
6. (10 pts) Explain why the following class hierarchy is not reasonable:
DefenseDepartment
General
Private
7. (10 pts) Give at least one example of a reasonable field for each of the following classes in the following class hierarchy. Be sure that the field is at the right level in the hierarchy.
Vehicle
Car
Airplane
Passenger
Fighter
Bomber
SpaceShip
8. (10 pts) Give at least one example of a reasonable method for each of the following classes in the following class hierarchy. Be sure that the method is at the right level in the hierarchy. Constructors, getters and setters don't count for this problem.
Vehicle
Car
Airplane
Passenger
Fighter
Bomber
SpaceShip
9. (10 pts) Are a Private and a Platoon in an encapsulation or an inheritance relationship? Explain
10. (10 pts) Present reasonable parent and child classes for the class Tree (the kind with leaves). Give a short explanation for why the classes you are proposing are in good parent-child relationships.
Explanation / Answer
1.
2.
3.
After Modification: MyClassD m = new MyClassD (23);
public class MyClassD {
int v = 12;
public MyClassD(int pV) {
int v = pV;
}
4.
5.
6.
7. fields are in Bold
Airplane
capacity
SpaceShip
capcity
8.
SpaceShip
Airplane
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