Editing Comparison of C Sharp and Java (section)

=== Migration compatibility ===
Java's type erasure design was motivated by a design requirement to achieve ''migration compatibility'' – not to be confused with [[backward compatibility]]. In particular, the original requirement was "''… there should be a clean, demonstrable migration path for the Collections APIs that were introduced in the Java 2 platform''".<ref name="Jcp.org"/> This was designed so that any new generic collections should be passable to methods that expected one of the pre-existing collection classes.<ref>{{cite web |author=Neal Gafter |url=http://gafter.blogspot.com/2004/09/puzzling-through-erasure-answer.html |title=Neal Gafter's blog: Puzzling Through Erasure: answer section |publisher=Gafter.blogspot.com |date=23 September 2004 |access-date=18 August 2013}}</ref>

C# generics were introduced into the language while preserving full backward compatibility, but did not preserve full ''migration compatibility'': Old code (pre C# 2.0) runs unchanged on the new generics-aware runtime without recompilation. As for ''migration compatibility'', new generic collection classes and interfaces were developed that supplemented the non-generic .NET 1.x collections rather than replacing them. In addition to generic collection interfaces, the new generic collection classes implement the non-generic collection interfaces where possible. This prevents the use of new generic collections with pre-existing (non-generic aware) methods, if those methods are coded to use the collection ''classes''.