Practice with Objects

Work through the detailed steps below to complete this program.

ELEVATOR PROGRAM

You'll be making two classes similar to the Toyota and CarTest classes that we did in class.
So, one class, Elevator.java contains all of the properties and methods that create and control the elevator.
The other class ElevTest.java is a class which has the main() method. This class will create the elevators and make them do things. The Elevator class does not have main().

Put comments at the top of each class: your name, date, program information

In the Elevator class make the following static (class level) variables:

• manufacturer (initial value = "Otis" or whatever you want)
• topFloor (value = 17)
• maxOccupants (value = 23)
• powerOn (value = true)

Make all but the last one (powerOn) constants so that they can't be changed. Hint: look up "final"

Make the following instance (object level) variables:

• floor //integer showing which floor they are on
• people //integer - how many people are in the elevator
• doorsOpen //boolean - are the doors open or closed?
• direction //integer: +1 = up; -1 = down ** I think that this variable is not actually needed

Make all of these variables private.
Set the default values: floor=1; people=0; doorsOpen=false; direction=+1
Note: you can also set default values in constructors

Make two constructors

• an empty constructor
• a constructor which takes the initial floor of the elevator as an argument / parameter
  (This constructor needs to check to see if the initial floor is between 0 and the top floor. If not, start the elevator at floor 1)

You'll be using both of them.

Make two(?) static methods

Make some sort of method for turning the building power on or off (and checking if it is on or off). It has to be static so that it affects the whole building.
The method should print out a message ONLY if the state changes. If the power is already on and you try turning it on, nothing happens. But if it is OFF and you turn it ON, then in prints "Building power restored" (or similar).

• setPowerState(T/F) // true = on, false=off
• getPowerState() //maybe there is a better name for these. setPowerOn(T/F)?
  (This method is only necessary if you're trying to determine the building power from another class. Inside this class you can just check powerOn.)

Make instance methods:

All of these methods should print out error messages if something is wrong. They should not print out messages if they do what they are supposed to do.

• up() = move up one floor
• down () = move down one floor
• goToFloor(n) = go to floor n

when moving the elevator:

• make sure the power is on
• make sure the doors are closed
• make sure you don't go above the top floor or below the ground floor
• if any of these happen, do a System.out.println ( ) with the error message

You can have some variation of methods to move the elevator, as long as the functionality is basically the same. ie. maybe you don't need up() and down()

• openDoors()
• closeDoors()
• these two methods need to check if the power is on. If not, then error message
• addPeople(n)
• make sure that the doors are open
• make sure that you don't go above max occupancy
• make sure that n is positive
• removePeople(n)
• make sure that the doors are open
• make sure that you don't go below zero
• make sure that n is positive
• toString()
  toString() overrides a method from the Object class, so it has to be public. You should also be using @Override.
  Ideally, all objects that you make should have a toString() method that describes the state of the object.
• this should return a string of one line of text that contains:
• the manufacturer, floor, number of people, and whether the doors are open or closed

If you can't figure out how to write the toString() method, have a look in the HTML source of this page. You'll find a version there as a comment.
Type "CTRL-U" to see page source. Then go to line 110 or so, you'll see the toString method there

In the ElevatorTest class:

Do the following:

• make two elevators, call them south and east. (Elevator south = ... )
• make east start on the 5th floor

The following are examples of things you can try with your elevator.
You're basically testing out the functionality of each method to see if they work as they are supposed to:

• have 10 people get on south at the ground floor
• 3 get out on floor 4 and the rest get out on the top floor
• have 8 get into east on the 5th floor.
• try and add 30 more on the 8th floor
• try to go above the top floor; try to go to a negative floor
• move both elevators to the second floor
• open the doors on east
• have a power failure
• then test to make sure that your elevators can't move or close or open doors
• restore the power (you should see a message)
• restore the power again (no message, the power is already on)
• make elevator south move up one floor at a time from the ground floor to floor 10, stopping on each floor and opening and closing doors

print out toString each time someone gets on or off the elevator
· if you want to print out toString anywhere else, you can.

Optional: try and set both elevators to exactly the same state and then see if they are equal. They won't be since == does not work for objects. You would have to use .equals() but there is no .equals() in the Elevator class (yet) and the Object.equals() does not help. So we would have to write our own .equals() method.

I was trying to see if I could make a graphical display of the elevators, but it is too hard just using text output. It could be done using a GUI.