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Reading the Javadoc


The Application Programmer's Interface (API)  is the set of classes and methods a software library exposes for a programmer's use.  You use the API to accomplish something with that software.  It is important for this API to be well-documented.

If you chose the Help -> Show Jurtle API command, your web browser will open one of a set of pages known as javadoc.  Javadoc is a form of Java programmer's documentation that can be generated directly from a class's source code and embedded comments.  It is an essential resource for programmers, so you need to understand how to read it.

The page displayed when you show the Jurtle API is a "table of contents" page for the package (code library) com.otherwise.jurtle.  There are two public classes in this package Console and Turtle.



If you click the Turtle link you will be taken to a new page with a brief description of the Turtle class, where all the methods and instance variables are listed and described.



This page can be broken into a number of different sections:

Class Inheritance

This section shows what package the class is in and where it is in the inheritance hierarchy.  As we can see, Turtle is in the com.otherwise.jurtle package and it inherits directly from  Object.

Class Description

The Class Description comes from the javadoc comment you put at the top of the class's file.  It usually gives a brief description of what the class does and how to use it.

Field Summary

This section lists all the static and instance variables (also called fields) the class declares.  The left-hand column shows the field's data type and whether it is a static variable or an instance variable.  The right-hand column shows the variable's name.  The Turtle class declares only a single static integer called NO_PAUSE.

Constructor Summary

The next section is the Constructor Summary where the class's constructors are listed.  Recall that constructors are special methods used to create new instances of a class.  There is only one constructor for the Turtle class, and it takes no arguments.

Method Summary

The Constructor Summary is followed by the Method Summary section.  All the methods defined in the class are listed with a brief, one-line summary.  The left-hand column shows the method's return type; i.e., the data type of the value returned by the method (or void, if there is none).  The right-hand column shows the method name and the arguments it takes. 

The javadoc for the Turtle class only lists public methods.  When generating javadoc, it is possible to specify that private or protected methods also be listed.

Method Detail

By clicking on a method name in the Method Summary section, you will be taken to a location later in the same page where the detailed method description is given.



The detailed description shows the method's name followed by a line showing its declaration in the source file.  Below that is the full description of the method as found in the javadoc comment associated with that method.  Finally, there is a description of the parameters (arguments) the method takes.  Again, the descriptions are taken from the source code's javadoc comments.

Documenting your code

When writing a code library that others will be using, it is important to do a thorough job documenting the API.  Most of the code you will be writing in Jurtle will be stand-alone and not for use by other programmers.  Nevertheless, it is still important to comment your code, and a good way to do this is with javadoc comments.  The turtles in the Examples folder show how you might use javadoc comments to document your code.