Java, A Beginner's Guide, 5th Edition, 5th Edition

Erasure

Usually, it is not necessary for the programmer to know the details about how the Java compiler transforms your source code into object code. However, in the case of generics, some general understanding of the process is important because it explains why the generic features work as they do—and why their behavior is sometimes a bit surprising. For this reason, a brief discussion of how generics are implemented in Java is in order.

An important constraint that governed the way generics were added to Java was the need for compatibility with previous versions of Java. Simply put: generic code had to be compatible with preexisting, nongeneric code. Thus, any changes to the syntax of the Java language, or to the JVM, had to avoid breaking ...