©2006 Felleisen, Proulx, et. al.
Collect and finish the RoomEditor class and connect it to the shape
classes. Solution
Modify the presentation of the room so that it fits within the canvas and there is 20 point margin around the room. Make the margin black. Solution
Recall problem 2.1 (exercise 4.5 in the book):
Develop a program that creates an on-line gallery from three different kinds of records: images (gif), texts (txt), and sounds (mp3). All have names for source files and sizes (number of bytes). Images also include information about the height, the width, and the quality of the image. Texts specify the number of lines needed for visual representation. Sounds include information about the playing time of the recording, given in seconds.
Develop the following methods for this program:
timeToDownload, which computes how long it takes to download a
file at some given network connection speed (in bytes per second);
smallerThan, which determines whether the file is smaller
than some given maximum size;
sameName, which determines whether the name of a file is the
same as some given name. Solution
Collect all the pieces of oneMonth and insert the method definitions
in the class hierarchy for logs. Develop examples and include them with the
test suite. Draw the class diagram for this
hierarchy. Solution
Suppose the requirements for the program that tracks a runner's log includes this request:
The runner wants to know the total distance run in a given month.Design the method that computes this number and add it to the class hierarchy of problem 4.4 (exercise 13.1 in the book).
Consider designing two different versions. The first should just follow the design recipe. The second should take into account that methods can compose existing methods and that this particular task can be seen as consisting of two separate tasks. Where would you put the second kind of method definition in this case? (See the next chapter.) Solution
Suppose the requirements for the program that tracks a runner's log includes this request:
The runner would like to see the log with entries ordered according to the pace computed in minutes per mile in each run, from the fastest to the slowest.Design this sorting method.
Design the sorting method to sort the log with entries ordered according to the date of the entry. Solution
+---------------+ | IGUIComponent | <---------------------------------+ +---------------+ | +---------------+ | | | / \ | --- | | | +--------------------+--------------------+-------------------+---------- ... | | | | | | +--------------+ +----------------+ +--------------+ +--------------+ | | BooleanView | | TextFieldView | | OptionsView | | ColorView | | +--------------+ +----------------+ +--------------+ +--------------+ | | String label | | String label | | String label | | String label | | +--------------+ +----------------+ +--------------+ +--------------+ | | | ... ---------+ | | | +--------+ | | ITable |<-------------+ | +--------+ | | +--------+ | | | | | / \ | | --- | | | | | ------------------ | | | | | +------+ | +---------+ +--------------+ | +------------> | IRow |<-------------+ | | MTTable | | AddRow | | | +------+ | | +---------+ +--------------+ | | +------+ | | +---------+ | Table rest |----+ | | | | | IRow first |---------------+ / \ | | +--------------+ --- | | | | | +------------------+ | | | | | | +------------------+ +-------+ | | | ConsRow | | MTRow | | | +------------------+ +-------+ | | | | +-------+ | | | GUIComponent fst |----------------------+ | IRow rst |---------------+ +------------------+
Figure 1: A hierarchy of GUI components
4.7 Problem (13.11 OPTIONAL)
Figure 1 contains a class diagram that describes the GUI hierarchy of exercise 6.5 in the book. Note that one of its interfaces,
ITable, refines another interfaceIGUIComponent.Add templates to each box in this diagram. Do not assume anything about the return type; do not design classes. Solution
+------+ | IExp |<----------------------------+ +------+ | / \ | --- | | | ---------------------------- | | | | +-----------+ +-----------------+ | | IntVal | | OpExp | | +-----------+ +-----------------+ | | int value | +-| IOperator rator | | +-----------+ | | IExp rand1 |----+ | | IExp rand2 |----+ | +-----------------+ | | v +-----------+ | IOperator | +-----------+ / \ --- | ------------------ | | +-----------+ +-----------+ | PlusOp | | TimesOp | +-----------+ +-----------+ | String op | | String op | +-----------+ +-----------+
Figure 2: Representing arithmetic expressions
4.8 Problem
Modify the classes from the problem 3.1 to represent only the arithmetic expressions, as shown in the class diagram in figure 2. Design the method eval that produces an instance of
IntValthat represents the integer value of the arithmetic expression. Solution
4.9 Problem
Given a Java program as defined in the Problem 3.2 determine whether a given class is correctly defined. Divide the task into the following steps:
1. Determine whether a given name is a valid type name in a program.
2. Verify that all interfaces defined in a class within a given program are valid interface name. Use a helper that determines whether every interface name in a list of interface definitions is contained in the given list of interfaces. Make sure you follow the design recipe.
3. Verify that in a class every field type represents a valid type in the given program. Also make sure that the type of the field is not the same as the name of the class in which it is defined.
4. Combine the above methods to verify that a class definition is valid in the given program.
Note: This does not constitute a complete set of condition for a correct program definition. Additionally, we would also have to make sure no type names are repeated, and no field names are repeated within a given class definition. There may be other concerns as well.. Solution
4.10 Writing Problem
Writing assignments are separate from the rest of the assignment for the week. You should work on this assignment alone, and submit your work individually on the due date for the rest of the homework. The answer should be about two paragraphs long -- not to exceed half a page or 300 words.
Software errors can be very costly - in term of financial losses, violating person's privacy, or even physical harm or death. Find two examples of the situations where the software error caused such damage. Describe each error, its impact, and how it could have been prevented. Include references to the sources you consulted. Solution