Homework Assignment 1
Late homework assignments will not be accepted, unless you have a valid written excuse (medical, etc.). You must do this assignment alone. No team work or “talking with your friends” will be accepted. No copying from the Internet. Cheating means zero.
Create a new Eclipse workspace named “Assignment1_1234567890” on the desktop of your computer (replace 1234567890 with your student ID number). For each question below, create a new project in that workspace. Call each project by its question number: “Question1”, “Question2”, etc. Answer all the questions below. At the end of the assignment, create a ZIP archive of the whole workspace folder. The resulting ZIP file must be called “Assignment1_1234567890.zip” (replace 1234567890 with your student ID number). Upload the ZIP file on iSpace.
Question 1
You are a software engineer who has to write the software for a car transmission. The transmission has five gears numbered from 1 to 5 to move forward, one neutral gear position numbered 0 where the car does not move, and one reverse gear numbered -1 to move backward. The transmission has a clutch, and the driver of the car can only change gear if the driver is currently pushing the pedal for the clutch.
Write a
Transmission class with the following UML specification:
+——————————————+ | Transmission | +——————————————+ | – clutchPedalPushed: boolean | | – gear: int | +——————————————+ | + Transmission() | | + isClutchPedalPushed(): boolean | | + pushClutchPedal(): void | | + releaseClutchPedal(): void | | + getGear(): int | | + upShift(): void | | + downShift(): void | | + skipGears(int gear): void | | + testTransmission(): void | +——————————————+
where:
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clutchPedalPushed is a private instance variable describing whether the pedal for the clutch of the transmission is currently pushed by the driver or not.
gear is a private instance variable describing the gear number in which the transmission currently is. Transmission is a public constructor that creates a Transmission object. When a transmission is created, the pedal for its clutch is not currently being pushed and the transmission is in the neutral gear 0. isClutchPedalPushed is a public method that returns as result a boolean indicating whether the driver is currently pushing the pedal for the clutch of the transmission or not.
pushClutchPedal is a public method that pushes the pedal for the clutch of the transmission; if the pedal is already currently being pushed then this method does nothing.
• releaseClutchPedal is a public method that releases the pedal for the clutch of the transmission; if the pedal is currently not being pushed then this method does nothing.
• getGear is a public method that returns the gear number in which the transmission currently is.
• upShift is a public method that shifts the transmission up by one gear. The transmission can only shift up if the pedal for the clutch of the transmission is currently being pushed by the driver. If the pedal for the clutch of the transmission is not currently being pushed then the upShift method must print a message to the screen “Cannot shift up when the clutch is engaged” and the transmission does not change gear. If the transmission is already in gear 5 then the upShift method must print a message “Cannot shift
higher than 5th gear” and the transmission does not change gear.
• downShift is a public method that shifts the transmission down by one gear. The transmission can only shift
down if the pedal for the clutch of the transmission is currently being pushed by the driver. If the pedal for the clutch of the transmission is not currently being pushed then the downShift method must print a message to the screen “Cannot shift down when the clutch is engaged” and the transmission does not change gear. If the transmission is already in gear -1 then the downShift method must print a message “Cannot shift lower than reverse gear” and the transmission does not change gear.
• skipGears is a public method that shifts the transmission directly to the given gear.
o The transmission can only change gear if the pedal for the clutch is currently being pushed. If the pedal for the clutch of the transmission is not currently being pushed then the skipGears method must print a message to the screen “Cannot shift to another gear when the clutch is engaged”
and the transmission does not change gear.
o If the given gear number is strictly less than -1 or strictly bigger than 5 then the skipGears method must
print a message “Cannot shift to gear XXX” (where XXX is replaced in the real output by the
given gear number) and the transmission does not change gear.
o If the given gear number is the same as the current gear of the transmission then the skipGears method
must print a message “Cannot shift to the same gear” and the transmission does not change
gear.
o If the car is currently moving forward and the driver tries to shift to the reverse gear, or if the car is
currently moving backward and the driver tries to shift to one of the forward gears, then the skipGears method must print a message “Cannot reverse direction while moving” and the transmission does not change gear. (This is to prevent the car from suddenly switching from moving forward to moving backward, or from suddenly switching from moving backward to moving forward, without going in between through the neutral gear position and stopping.)
• testTransmission is a public static method that tests all the code in your Transmission class. Test all your methods from the simplest one first to the most complicated one last.
Once you have written the Transmission class, you can test it by adding the following code in a separate class:
public class Start {
public static void main(String[] args) {
Transmission.testTransmission(); }
}
This code calls the static testTransmission method of the Transmission class, which should then run all your
tests.
Here are a few extra instructions:
• Give meaningful names to your variables so we can easily know what each variable is used for in your program.
• Put comments in your code (in English!) to explain WHAT your code is doing and also to explain HOW your
program is doing it.
• Make sure all your code is properly indented (formatted). Your code should be beautiful to read.
Failure to follow these instructions will result in you losing points.