Supporting Design by Contract in Java

Design by Contract is a valuable design method for trusted software components. Eiffel shows how to provide appropriate language support for it. However, no such concepts currently exist in Java. Full integration of them into Java may help to improve and guarantee the quality of Java classes. We briefly compare several approaches to extend Java in this way and present our model and a compiler that translates extended Java code into JVM byte code. Our Java extension integrates preconditions, postconditions, and invariants as in Eiffel while respecting the characteristics of Java. The evaluation shows that Design by Contract can be added efficiently to Java while keeping compatibility.