Welcome to the FactGuru knowledge base about Java

Docubase

This kb (knowledge base) is linked to an associated web document http://www.site.uottawa.ca/~tcl/factguru1/java/javadocument.html that is a brief introduction to Java in normal English format. What this means is, if you are in the kb and see a link icon beside a fact, clicking on it will take you to that fact in the document. Conversely, if you are in the document and see a link, it will take you to that subject in the kb. The combination of a document and a knowledge base is referred to as a docubase.

Subject Selection

The left pane shows what we call subjects. You can display these in one of three ways by clicking on the tabs at the top:

1. arranged in a hierarchy, in which there is a pull-down menu that choose the type of hierarchy

• First on this menu you may choose a "concept hierarchy", in which each subject "is a" kind of" the subject above it. For example, "city is a kind of municipality". This hierarchy can have actual instances at the bottom, as in "Ottawa is an instance of a city", or "while is a keyword in Java"
• Second a "topic hierarchy", that arranges subjects like the table of contents of a book, ie by any classification scheme that seems appropriate. Hence under "Ottawa" you might find "restaurants".
• Third, a hierarchy of parts, ie if A is under B then A is a part of B. (This is not used in the Java kb.)

2. arranged alphabetically

3. as a graph. The graph is a fixed GIF image of the whole kb. If you click on nodes near the top, that subject will come up in a new window.

Searching

In hierarchy and alphabetical modes, you may search for a subject, by using the Find box or press Ctrl F. You must then click on the subject to make the information appear in the right pane.

Right Pane

If you click on a subject in the hierarchy, you will see facts about that subject appear in this pane. Any word in a fact that is underlined is a hyperlink that takes you to that subject. Under the facts for the subject you have selected will appear facts for its parents in the hierarchy that it has inherited. Thus under "cat" facts you would also see "mammal" facts, since cats are mammals.

The facts are split into syntactic sections, but these are not visible. First, there are simple facts, that have a subject, a verb (with possible modifiers), and often a word or two following the verb that signifies and attribute or relation to something ("colour" or "employer" or "to eat") followed by a phrase that specifies more precisely what this something is, and possibly more simple modifying phrases after that.

Sometimes a fact is not unconditionally true of the subject. We then use a compound fact made up of simple facts connected by keywords, for example:

• if a class has one or more abstract methods
• or the class does not implement all of its superclass's abstract methods
• then the class must be declared abstract

Subject Comparison

You can compare what the differences are between all the children of a subject by clicking on the Compare tab in this pane.

Facets

Some facts have additional information attached, called facets. These appear at the right as an arrow icon, and appear on mouseover. Usually they show the source of the fact.

Disclaimer

The information contained in this knowledge base is for demonstration purposes only and is not guaranteed to be accurate.

This knowledge base was created from a number of sources, including the Java Tutorial at Sun.

© Fact Guru, 2001

since Nov. 21, 2001