The following directories contain programs written in the JOOS language. In each directory you will find a Makefile which shows how make the programs in the directory (i.e. which .java files go together to form an application). The following directories contain Java applications (not applets).
  • AwtDemos: examples of using the Abstract Windows Toolkit.
  • Network: simple examples of interacting over the network.
  • Simple: a relatively large collection of simple Java programs.
  • Threads: simple, multi-thread programs.
The following directories contain Java applets. You may run any of the .html files in the first two directories via the JDK appletviewer, or via a browser that supports Java. Most examples have been taken from textbooks and modified so that they are written in JOOS. The changes made to make them into JOOS program includes:
  • Making the constructors explicit, and conforming to JOOS specifications with an explicit call to the super constructor.
  • Since JOOS does not support constants, all constants (particularly those from the Java awt libraries) must be accessed via nullary functions found in the JOOS libarary class called JoosConstants. You may refer to the file $JOOSDIR/Lib/joos/lib/JoosConstants.java to see all of the constants supported in this manner.
  • Since JOOS does not support overloading, the JOOS external declarations only support one alternative (usually the most general one) for each method in Java libraries. In some cases, for example the add method in the Container class, both alternatives are really needed. In this case there is a JOOS wrapper class called JoosContainer that provided a new name for each kind of add (addString and addPosition).
  • Some Java libarary classes have static members and/or classes. In order to get this functionality, one needs to use the appropriate wrapper JOOS class. A good example of this is the JoosDimension class that provides a wrapper to the Java Dimension class.
  • Java has quite a rich class structure to support various kinds of I/O. All JOOS I/O is simple, and is done using the functions found in the JoosIO class.
  • JOOS does not support exceptions, and so it is not possible to directly call Java library methods that raise exceptions that must be caught (i.e exceptions that are not Runtime exceptions). Thus, some JOOS libarary classes are provided that wrap the exception raising methods inside a method that catches the exception and returns true if an exception was caught (for example, sleep in JoosThread).
  • Since JOOS does not support real numbers, and some awt functions require real numbers as input (GridBagConstraints), there is a JOOS version (JoosGridBagConstraints), that uses JoosFractions to represent non-integers.