Goals: Learn to abstract common code and use custom constructors.
the names of classes,
the names and types of the fields within classes,
the names, types and order of the arguments to the constructor,
the names, types and order of arguments to methods, or
Make sure you follow the style guidelines that Bottlenose enforces. For now the most important ones are: using spaces instead of tabs, indenting by 2 characters, following the naming conventions (data type names start with a capital letter, names of fields and methods start with a lower case letter), and having spaces before curly braces.
You will submit this assignment by the deadline using the Bottlenose submission system. You may submit as many times as you wish. Be aware of the fact that close to the deadline the Bottlenose system may slow down to handle many submissions - so try to finish early.
There will be a separate submission for each problem - it makes it easier to grade each problem, and to provide you with the feedback for each problem you work on.
This assignment has only one part:
Due Date: Thursday, October 5th, 9:00pm
Work out these problems on your own. Save them in an electronic portfolio, so you can show them to your instructor, review them before the exam, use them as a reference when working on the homework assignments.
Problems 18.1 - 18.4 on page 225
Problem 18.5 on page 229
Problem 18.6 on page 234
Problem 19.4 on page 263
In this problem, our data will represent different kinds vehicles. Each vehicle has a name, passenger capacity, per passenger fare, and fuel capacity. Different kinds of vehicles can also contain additional information as shown in the supplied Vehicle.java file.
Note: only the totalRevenue() method is properly implemented. The others are stubs that currently return a dummy value, so the code will compile but not yet work.
Warmup: Download the file and work out the following problems:
Make one more example of data for each of the three classes and add more tests for the totalRevenue() method (that is already defined) using them.
Design the method fuelCost which produces a double with the cost to fully fuel the vehicle. We assume airplanes consume kerosene, which costs 1.94 dollars per gallon, while trains and buses run on diesel, which costs 2.55 dollars per gallon.
Design the method perPassengerProfit, which produces a double with the profit per passenger. For this problem, the profit will be the total revenue minus the fuel cost.
Design the method format which produces a String showing the name and passenger capacity of this vehicle. The name and passenger capacity should be separated by a comma and a space and end with a period.
Design the method sameVehicle that determines whether the this vehicle is the same as the given one.
Once you have finished these methods and are confident that they work properly, save the work you have done to a separate file. Do not submit the code as written so far. The problems below are the main point of this exercise, and it will be helpful for you to preserve the code written so far as a reference against which to compare your revised code below. Again, submit only the work below.
Look at the code and identify all places where the code repeats —
the opportunity for abstraction.
Lift the common fields to an abstract class AVehicle.
Make sure you include a constructor in the abstract class, and change the constructors in the derived classes accordingly. Run the program and make sure all test cases work as before.
For each method that is defined in all three classes decide to which category it belongs:
The method bodies in the different classes are all different, and so the method has to be declared as abstract in the abstract class.
The method bodies are the same in all classes and it can be implemented concretely in the abstract class.
The method bodies are the same for two of the classes, but are different in one class —
therefore we can define the common body in the abstract class and override it in only one derived class.
Now, lift the methods that can be lifted and run all tests again.
A Time can be represented as an hour between 0 and 23, minute between 0 and 59, and second between 0 and 59.
Define the Time class with:
a main constructor that enforces these constraints, and throws an exception if they are violated.
Clarification: The messages for the exceptions should start with: "Invalid hour: ", "Invalid minute: ", or "Invalid second: " and include the invalid number.
a convenience constructor that takes just hours and minutes, and provides a default value of zero seconds for the time.
a constructor that takes an hour between 1 and 12, minutes between 0 and 59, and a boolean flag isAM that is true for the morning hours, and initializes the Time’s fields accordingly.
Be sure you have removed as much code duplication as you can from these three constructors.
Test your implementation carefully: what are the corner cases you should worry about?
Design and implement a sameTime method for Time class. Be sure to test it thoroughly, checking for any strange edge cases that might arise. How does your sameness checker interact with your constructor(s?) for Time?