Thread: how I can solve this program ?

hi all

Can anyone understand me how i can solve this program ?

I understand its idea and I solved the first class "Vehicle" But stopped at the other classes

( class "Vehicle" is under the question )

The aim of the project is to write two applications: one for Car Rent Company, the other one is for Bus Company. The class Vehicle is going to be used as a super class for the two companies i.e. The Car.java and Bus.java are going to implement the Vehicle. Each one of them is going to reuse the Vehicle differently according to the company needs.
Write a program that contains the following classes:
1) Create a class called Vehicle that contains fields for the vehicle's licensePlateNumber, maker and modelName. Provide both a default constructor and 3 argument constructor. Provide accessor (get) and mutator (set) methods for the fields.

2) Create a subclass of Vehicle called Car that contains a field for the car availability in the Garage (to show it is avilable to use or it is already rented).

3) Create a subclass of Vehicle called Bus that contains fields for the number of seats and number of avilable seats in the Bus.

4) Write two main applications. First one creates a menu for the Car Company and declares an array of 3 cars; the second application creates a menu for the Bus Company and declares an array of 3 Buses. An example for the array declarations:

Car [] mycar = {
New Car("123AAA","Toyota","Corolla"),
New Car("1432BBB","Honda","Stream","") , new Car("121BCA","Toyota","Avalon")
};
Bus [] mybus = {
new Bus("787FFF","Toyota"," HIACE "),
new Bus("909GGB","Ford","Flex",""), new Bus("888YKL","ryanbus","AECMerlin") };


5) Bothe menu should allow its users to add and delete a new car or a new bus. The Car Company menu should give an option to rent a car from the Garage. This is done by changing the value of the car availability. On the other hand, the Bus Company will have an option in the menu to reserve a seat based on the number of seats that are avilable on the bus.


Welcome to Car Company
Main Menu

1. Add a new car.
2. Delete a car.
3. Rent a car
4. Exit.


Welcome to Bus Company
Main Menu

1. Add a new bus.
2. Delete a bus.
3. Reserve a seat.
4. Exit.


 Hints1: to rent a car (option3 in the menu), you should display all the cars in the array, the user will select one then you check if this car is avilable in the garage. If it is avilable then set its availability value to indicate that this car is used now.

 Hints2: to reserve a seat (option3 in bus menu), you should display all the buses in the array, then the user will select one then you check if there are enough seats still exit. Then you subtract the number of avilable seats by1.

class "Vehicle" :

public class Vehicle {
 
private int	licensePlateNumber ;
private String maker;
private String modelName;
 
 
 public Vehicle(int licensePlateNumber,String maker,String modelName) 
 	{
 	this.licensePlateNumber=licensePlateNumber;
 	this.maker=maker;
 	this.modelName=modelName;
    }
 
    public Vehicle() 
    {
    }
 
    public void setLicensePlateNumber(int LPN)
    {
    licensePlateNumber=LPN;	
    }     	
     public void setMaker(String m)
    {
    maker=m;	
    }
    public void setModelName(String MN)
    {
    modelName=MN;
    }
 
 
     public int getLicensePlateNumber()
    {
    return licensePlateNumber;	
    }     	
     public String getMaker()
    {
    return maker;	
    }    
    public String getModelName()
    {
    return modelName;
    }  
 
 
 
}

New Car("123AAA","Toyota","Corolla"),
New Car("1432BBB","Honda","Stream","") , new Car("121BCA","Toyota","Avalon")

It appears there's a comma after Stream.

Also, new isn't capitalized.

public class Car extends Vehicle
{

// new methods and methods that are overridden or overloaded.

}

public class Bus extends Vehicle
{

// new methods and methods that are overridden or overloaded.
}

Not quite sure on this one, but try

public Car(int licensePlateNumber,String maker,String modelName, boolean availability)
{
super(licensePlateNumber, maker, modelName); // calls constructor of Vehicle class
this.availability = availability;
setAvailability(availability);
}
 
public void setAvailability(boolean availability)
{
this.availability = availability;
}
 
public boolean getAvailability()
{
return availability;
}

 
public Bus(int licensePlateNumber,String maker,String modelName, int numberOfSeats, int numberOfAvailableSeats)
{
super(licensePlateNumber, maker, modelName);
this.numberOfSeats = numberOfSeats;
this.numberOfAvailableSeats = numberOfAvailableSeats;
setNumberOfSeats(numberOfSeats);
setNumberOfAvailableSeats(numberOfAvailableSeats);
 
}
 
public void setNumberOfSeats(int numberOfSeats)
{
this.numberOfSeats = numberOfSeats;
}
 
public int getNumberOfSeats()
{
return numberOfSeats;
}
 
public void setNumberOfAvailableSeats(int numberOfAvailableSeats)
{
this.numberOfAvailableSeats = numberOfAvailableSeats;
}
 
public int getNumberOfAvailableSeats()
{
return numberOfAvailableSeats;
}

As for how to use them in the "main", you can simply use the objects in your arrays.

However, it would be better if your constructor for Vehicle called the three set methods of that class and used the parameters passed to the 3 arg constructor to set the values. This, with the new code I gave, will set the values so you don't get a Null Pointer Exception, or shouldn't, and also, when you call the Vehicle constructor, should call the superclass' constructor and which calls the three set methods for you. You don't need to rewrite the three set methods of your Vehicle class unless you plan to change what they do for your subclasses.

What you mean by "adding" or "deleting" a car or bus I'm not quite sure. You can cancel a ticket or a bus seat so that it becomes available, but you cannot, say, delete the Car or Bus at index 2. Your delete, I'm assuming, for Car, in your main class, should call the setAvailable(true) for the Car at that index in the array. Your delete for Bus, I'm assuming, should
setAvailableSeats(getAvailableSeats() + 1) for the Bus at that index in the array.

add function : the user enter new car or bus " enter the 3 varible " its licensePlateNumber ,its maker and its modelName" for example "123AAA","Toyota","Corolla" and I add this new car user entered it to array of car

That's simple.

For instance, to create one Bus object and one Car object in the main method, you

public static void main(String[] args)
{
 
 
 
Car car = new Car(12345, "Luke Skywalker", "Model K", 1);
 
Bus bus = new Bus(23456, "Elvis Presley", "Megabus 2012", 200, 35);
// a.k.a for the array, buses[0] = new Bus(bus parameters);
 
}

As for details, consider having a toString() method for Car and Bus that returns the values. Use the get methods, not the variables themelves in the Car and Bus classes, to do that.

Use a for loop to print out the stuff by calling the toString() of each Car object in the array.

int choice = 0;
 
while (choice !=4)
{
 
System.out.println("Welcome to Car Company");
System.out.println("Main Menu");
System.out.println("");
System.out.println("1. Add a new car.");
System.out.println("2. Delete a car.");
System.out.println("3. Rent a car");
System.out.println("4. Exit.");
 
choice = console.nextInt();
int carChoice = 0;
if (choice ==1)
{
System.out.println("Enter a car to choose between 1 and 3.");
carChoice = console.nextInt();
 
if (carChoice ==1)
{
if (cars[carChoice -1].getAvailability() == true)
{
// output
cars[carChoice -1].setAvailability(false);
}
}
}
}

You get the picture.