Jeliot

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Jeliot A powerful Java tutor for beginners

• Boro Jakimovski
• Institute of Informatics
• Faculty of Natural Sciences and Mathematics
• University Ss Cyril and Methodius
• Skopje, Macedonia

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Jeliot

• Jeliot family is designed to aid students to
  learn programming in Java
• Useful for teaching Java as first course
• Uses Program Animation shows the execution of
  a program by means of a multimedia display.
• Executes the program step by step with adjustable
  speed
• Displays every step in very understandable way

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Jeliot usage

• The tool can be used for
• For lectures
• Assessment
• Interactive laboratory sessions
• Virtual courses

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Environment
Theatre
Code Editor
Output
Toolbar Editor
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Compilation
- After compiling the code the show is started
? - If there are any compilation errors that is
shown once the simulation starts ?
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Execution
Methods invoked Method variables
Current execution point
Evaluation of expressions
Memory space (instances)
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Execution
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Advantages

• Jeliot animated execution enables students to
• Better understand program execution
• Execution of programming structures
• Sequence
• If-else statements
• Loops
• Understand the concept of a pointers and memory

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Call tree
Call tree shows the operation execution
steps Good for recursion explanation
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Recursive Fibonacci
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Recursive Fibonacci
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Java issues

• All classes must be in a single source file.
• For I/O, import the package jeliot.io. which
  provides the methods
• void Output.println(),
• int Input.readInt(),
• double Input.readDouble(),
• char Input.readChar(),
• String Input.readString().
• Jeliot uses DynamicJava (http//koala.ilog.fr/djav
  a/) as a front-end and thus accepts almost all
  Java features that you would want to use for
  introductory programming, however, the
  implementation of the animation might not animate
  all features.

• Currently, the implementation includes
• Values of type String
• all primitive types and one-dimensional arrays.
• Expressions including all unary and binary
  operations except instanceof.
• All the control statements (if, while, etc.).
• Method invocation, including recursive
  invocation.
• Allocation of objects, constructors, invocation
  of methods on objects.
• Not implemented are
• Static variables.
• Calls to super(), except for super() at the
  beginning of a constructor.
• Arrays with components of reference type (except
  String).
• Conditional expressions exp?exp1exp2.
• Array initializers.

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Jeliot extensions

• Jeliot supports extensions to be built for
  collaboration
• Very good extension is BlueJ
• BlueJ is an interesting editor for Java
• Consists of
• UML Class diagram
• Editor
• Object inspection and testing

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BlueJ
UML Class diagram
Toolbox
Runtime command execution
Memory (Object instances)
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BlueJ

• Pop-up menu on selected class or object gives
  opportunity
• Invoke methods
• Instantiate objects
• Inspect objects
• Remove objects and classes
• Invoke the editor
• Compile the class

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Object inspection
- Allows students to test certain methods from
the classes (outside of the program) - In a way
they test the classes without writing an Java
application (main method)
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Debugger
Students can stop an execution of a method and
inspect the values of internal variables and
execute it step by step
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Jeliot and BlueJ
Students can also execute their programs in Jeliot
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BlueJ Capabilities

• Students can do the following using BlueJ
• Edit the code
• Compile the code
• Get more explanatory error messages
• Debug their programs (breakpoints, watches)
• Inspect object content
• Create applications and applets
• Incorporate existing classes in the projects

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Conclusion

• Jeliot and BlueJ can significantly increase
  students understanding of both structural and
  especially object-oriented programming
• Easy and fun to use
• Simple but still very powerful tools