Integration of Java Generics Into The jmle Tool Within Th

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Integration of Java Generics Into The jmle Tool
Within The Eclipse IDE

• Adrian Kostrubiak
• 9/16/08

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Overview

• Background
• Java Generics
• What is JML?
• The jmle tool
• Moving Forward

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Collections Without Generics

• LinkedList list new LinkedList()
• list.add(one) list.add(two)
• String first (String)list.get(1)
• Integer second (Integer)list.get(2)
• Compiles perfectly fine.
• However, this results in a ClassCastException!!

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Collections With Generics

• LinkedListltStringgt list new
• LinkedListltStringgt()
• list.add(one) list.add(two)
• String first list.get(1)
• Integer second list.get(2)
• This will not compile!

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Benefits To Using Generics

• Compile time safety checks
• Eliminates possibility of runtime errors
• No more unnecessary type casting
• Clearer code

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JML

• Java Modeling Language
• Exists in annotations before code modules
• Behavioral interface specification language
• Formally specify module behavior
• Design by Contract (DbC)
• Java style syntax

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JML Code Example

• /_at_ assignable \nothing
• ensures \result j k /
• int sumOfTwo(int j, int k) return(jk)
• /_at_ assignable myVal
• requires j gt 0
• ensures myVal \old(myVal) - j /
• void subtract(int j) myVal myVal - j

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JML Specification Language

• Formal language
• Used in system design, requirement and system
  analysis
• Not executable
• Higher level than code being described

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JML DbC

• Preconditions - whats expected
• requires
• Postconditions - whats changed
• ensures
• Class invariants - whats the same
• invariant

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JML Not perfect.

• Not executable on its own
• No support for generics (yet)
• Takes time to create a proper contract

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The jmle Tool

• Takes code with JML embedded
• Creates a Java constraint program
• Executed with the Java Constraint Kit

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The jmle Tool Why?

• Cant run JML code on its own
• Good to be able to easily check if a program is
  meeting its contract
• With JCK, everything is in Java - its easy

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jmle In Eclipse

• Program itself not run
• Runs constraint program
• Eases checking and understanding of constraints

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Moving Forward

• Currently no generic support in JML and jmle
• Implementing generics
• Push jmle from mere academic pursuit into actual
  industry

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Conclusions

• Generics are essential
• Addition of generics to JML makes it appealing
• Could even be used in industry