Submission
- Remove any extraneous debugging statements from your code.
- Upload all of the required files. Filenames are case-sensitive. Be sure to submit the most up-to-date version of your code.
- After testing on your computer, click the
Check Submitted Files button
to receive feedback from the autograder.
There is no need to mark (and unmark) the checkbox if you are submitting before the deadline.
Check Submitted Files
PercolationStats.java
to receive feedback on Percolation.java,
but you must submit
Percolation.java
to receive feedback on PercolationStats.java.
- Spotbugs is a program that looks for common bug patterns in your code. You should treat anything it reports as an error (though, occasionally there are false positives). The autograder uses SpotBugs 4.2.3 and the configuration file spotbugs.xml. It also uses the fb-contrib plugin, which detects additional bug patterns.
- PMD is a program that looks for common bug patterns in your code. The autograder uses PMD 6.34 and the configuration file pmd.xml.
- Checkstyle is a program that looks for common style issues in your program. The appearance of a warning message does not necessarily lead to a deduction (and, in some cases, it does not even indicate an error). You should pay particular attention to the custom checks, which are specialized to each program. The autograder uses Checkstyle 8.31, the configuration file checkstyle-cos226.xml, and the suppressions file checkstyle-suppressions.xml.
Testing
Yes. For some assignments, you will be given very clear instructions on how to implement the test client. In others, you will be asked to implement your own test client that tests the methods you have implemented. Although the autograder tests your code, you are expected to test your code before you use the autograder.
For grading purposes, your test client will satisfy the requirements if it calls every public method in your code at least once in a meaningful way (by printing the return value, for example). For genuinely testing your code, you will often need to do more than that.
In general, professional programmers must write code to carefully check and validate any user input.
In this course, however, you may assume that user specifies valid input.
For example, you may assume that the command-line arguments to PercolationStats are
two integers (and not, say, a string and a double).
Style
- Use meaningful variable names.
- Use straightforward logic and control flow.
- Declare variables to minimize scope. For example, don’t declare a variable to be an instance variable if it is used only as a local variable in one method. All instance variables must be private.
- Avoid unexplained magic numbers, especially ones that are used more than once.
- Avoid repetitive code.
Example 1:
if (isTrue)
doA();
doB();
doC();
doD();
} else {
doB();
doC();
doD();
}
This code can be written as:
if (isTrue)
doA();
doB();
doC();
doB();
Example 2:
doA();
doB();
doC();
doD();
while (isTrue) {
doA();
doB();
doC();
doD();
}
This code can be written as:
do {
doA();
doB();
doC();
doD();
} while (isTrue);
You can also declare a function doAll() (for e.g.) that calls doA(), doB(), doC() and use it as follows:
doAll();
while (isTrue)
doAll();
Always consider using functions to encapsulate repeated code. Avoiding repeated code using functions enhances readability, simplifies debugging and localizes future changes to a single place.
- Include a comment describing every method and class (whether public or private).
- Include a comment describing every instance variable (including those for nested classes).
- Use whitespace to make your program easier to read. For example, indent consistently, using 3 or 4 spaces for each indentation level. Configure your editor to use spaces, not tabs.
- Do not exceed 80 characters per line.
This rule also applies to the
readme.txtfile.
- Repetitive code.
- Meaningless variable names.
- Inconsistently indented code.
- Convoluted logic or flow control.
- Excessive code that is commented out.
- Insufficient commenting, including complicated algorithms that are not explained clearly by their comments.
Java
algs4.jar to your Java classpath.
Arrays.sort(),
java.util.LinkedList, java.util.ArrayList, java.util.TreeMap, and
java.util.HashMap?java.lang such as Math.sqrt()
and Integer.parseInt().
Memory Analysis
Queue<String>
and is implemented as a linked list of nodes, you should count the memory of the Node objects
(including references to the String objects)
but not the memory of the String objects themselves.
The String objects in the queue are allocated by the client of the queue,
whereas the Node objects are allocated by the queue itself.
Timing Analysis