Abstract:

Java offers the real possibility that most programs can be written in a type-safe language. However, for Java to be broadly useful, it needs additional expressive power. This paper extends Java in one area where more power is needed: support for parametric polymorphism, which allows the definition and implementation of generic abstractions. We discuss both the rationale for our design decisions and the impact of the extension on other parts of Java, including arrays and the class library. We also describe optional extensions to the Java virtual machine to allow parameterized bytecodes, and how to verify them efficiently. We have extended the Java bytecode interpreter to provide good performance for parameterized code in both execution speed and code size, without slowing down non-parameterized code.

• Introduction
• Language Extensions
  • Java Overview
  • Parameterized Definitions
  • Instantiation
  • Satisfying Where Clauses
  • Extending Interfaces
  • Implementations
  • Optional Methods
  • Alternate Constraint Mechanisms
• Virtual Machine Extensions
  • Parameterization without JVM Extensions
  • Bytecode Extensions
  • Verifier Extensions
  • Runtime Extensions
  • Performance Results
• Interaction of Parameterization with Java
  • Primitive Types
  • Java Arrays
  • The Java Type Library
• Conclusions
  • Acknowledgements
• Java Grammar Extensions
  • Interfaces
  • Instantiation
  • Classes
  • Methods
• JVM Extensions
• References

This research was supported in part by the Advanced Research Projects Agency of the Department of Defense, monitored by the Office of Naval Research under contract N00014-91-J-4136, and in part by a grant from Sun Microsystems.

Appears in ACM POPL '97, Paris, France, January 1997.
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