Type Erasure in Java

When generics are used, they're converted into compile-time checks and execution-time casts. Type erasure means that at execution time, there's no way of figuring out that is a String because that information has been erased. Type Erasure exists in order to keep java bytecode backwards compatible with old JVM versions. Instead of implementing generics through erasure, generics could be implemented through “reification.” These would be called reified generics and would retain the type information. For a pretty good introductory exploration of generics in Java, see http://beust.com/weblog/2011/07/29/erasure-vs-reification/.