Goals: Learn to use custom constructors, determine equality via dynamic-dispatch, and determine non-structural equality.
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.
The submissions will be organized as follows:
Due Date: Thursday, February 6th, 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
the weight of flour should be equal to the weight of sugar
the weight of the eggs should be equal to the weight of the butter
the weight of the eggs + the weight of the milk should be equal to the weight of the sugar (or flour)
Design the CakeRecipe class. The fields should be of type double and represent the weights of the ingredients as ounces. Provide three constructors for this class:
Your main constructor should take in all of the fields and enforce the constraints above to ensure a perfect cake recipe.
Provide another constructor that only requires one to enter the amount of flour, eggs and milk, in that order.
Provide another constructor that takes in the flour, eggs and milk in that order, but as volumes rather than weights and a boolean flag areVolumes.
You may assume that flour and milk volumes are measured in cups and each egg is measured as one unit of volume.
1 cup of sugar = 7 ounces
1 cup of flour = 4 and 1⁄4 ounces
1 egg = 1 and ¾ ounces
1 cup of butter = 8 ounces
1 cup of milk = 8 ounces
Remove as much duplicate code as possible from these constructors.
Implement the method sameRecipe(CakeRecipe other) which returns true if the same ingredients have the same weights to within 0.001 ounces.
Please submit your work in a file named CakeRecipe.java and put your examples and tests in ExamplesCakes.
Entertainment media are elements of the media that focus on delivering entertainment to the general public. These include magazines, television series, and podcasts. Every medium has a name and price. Different kinds of entertainment can also contain additional information as shown in the supplied Entertainment.java file.
Note: only the totalPrice() 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 totalPrice method (that is already defined) using them.
Design the method duration which produces an int with the number of minutes this entertainment provides. We assume a magazine provides 5 minutes of entertainment per page and TV series and podcasts provide 50 minutes of entertainment per episode.
Design the method format which produces a String showing the name and price of this entertainment. The name and price should be separated by a comma and a space and end with a period.
Design the method sameEntertainment that determines whether the this entertainment 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 AEntertainment.
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.