Instructions
For problems 1 through 4, explain why the code as shown is almost certainly not what the programmer intended, and how it should be fixed to work the way the programmer probably had in mind.
1. What is wrong with the following program and how should it be fixed?
1 publicclass MyClassA {
2 int v = 12;
3
4 public MyClassA (int pV) {
5 v = pV;
6 }
7
8 publicstaticvoid main (String args []) {
9 MyClassA m = new MyClassA ();
10 } // end main
11 } // end class MyClassA
2. What is wrong with the following program and how should it be fixed?
1 publicclass MyClassB {
2 int v = 12;
3
4 publicvoid MyClassB (int pV) {
5 v = pV;
6 }
7
8 publicstaticvoid main (String args []) {
9 MyClassB m = new MyClassB (23);
10 } // end main
11 } // end class MyClassB
3. What is wrong with the following program and how should it be fixed?
1 publicclass MyClassD {
2 publicstaticvoid main (String args []) {
3 MyClassC m = new MyClassC (23);
4 } // end main
5 } // end class MyClassD
6
7 class MyClassC {
8 int v = 12;
9
10 public MyClassC (int pV) {
11 int v = pV;
12 }
13
14 } // end class MyClassC
4. What is wrong with the following program and how should it be fixed?
1 publicclass MyClassE {
2 publicstaticvoid main (String args []) {
3 MyClassF m = new MyClassF (23);
4 } // end main
5 } // end class MyClassE
6
7 class MyClassF {
8 int v = 12;
9
10 private MyClassF (int pV) {
11 v = pV;
12 }
13
14 } // end class MyClassF
5. 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 publicclass MyClassG {
2 publicstaticvoid main (String args []) {
3 MyClassH m = new MyClassH (23, true);
4 } // end main
5 } // end class MyClassG
6
7 class MyClassH {
8 int v = 12;
9
10 public MyClassH (int x, boolean b) {
11 this (x);
12 }
13
14 private MyClassH (int pV) {
15 v = pV;
16 }
17
18 } // end class MyClassH
6. Explain why the following class hierarchy is not reasonable:
DefenseDepartment
General
Private
7. 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. 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. Are a Private and a Platoon in an encapsulation or an inheritance relationship? Explain
10. Present reasonable parent and child classes for the class Tree (the biological kind). Give a short explanation for why the classes you are proposing are in good parent-child relationships.