Lecture Set 13 Args Array and Commenting Review Arguments to Main Method Commenting Review 1 2 CMSC 131 Fall 2009 Jan Plane adapted from Bonnie Dorr Arguments to main Recall prototype of main method public static void main String args args is array of Strings args come from operating system When user runs executable s he can provide arguments Demonstrations of Using the Args array CMSC 131 Fall 2009 Jan Plane adapted from Bonnie Dorr 1 Types of Documentation Two kinds of code commentary in Java JavaDoc Implementation comments Interface comments from inside Eclipse from outside of Eclipse Common Errors in Commenting Too many comments This can obscure the flow of your program Too few comments Your intent may not be understood code is never self documenting Comments that repeat the code int total 0 initialize integer total to 0 Using comments to conceal unclear code just rewrite the code double a h w set the area a to the height h times width w double area height width Uninformative comments What the heck does that mean double d processValue Change later legacy Misleading erroneous comment These are dangerous for int i 0 i a length 1 i run through the whole array CMSC 131 Fall 2009 Jan Plane adapted from Bonnie Dorr 2 1 Javadoc Documentation Class comments Immediately prior to each public class add a javadoc comment that explains what the class does You can also add the following special tags which javadoc recognizes and provides special formatting for author the author of the class version the current software version number see refer the reader to related classes Example In Rational java Sample javadoc class comment This class implements a rational number object and provides methods for performing arithmetic on rational numbers see java lang Math author Schultzie von Wienerschnitzel III version 3 14159 public class Rational CMSC 131 Fall 2009 Jan Plane adapted from Bonnie Dorr 3 Javadoc Documentation Method comments Immediately prior to each public method add a javadoc comment explaining what the method does the meanings of the parameters the return value and any errors The following tags are recognized param give the name and description of each parameter There should be one for each parameter return describe the return value unless it is void throws exceptions that could propagate out from this method deprecated Usually for system use indicates that a method should be avoided since better alternatives exist Example Multiplies two rational numbers and returns their the product param q The first operand param r The second operand return A reference to a newly created Rational with the sum public static Rational multiply Rational q Rational r CMSC 131 Fall 2009 Jan Plane adapted from Bonnie Dorr 4 2
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