.NET StreamReader and StreamWriter already default to UTF-8. The only thing that is changing here is the default encoding when Java serializes a String to bytes

.NET StreamReader and StreamWriter already default to UTF-8. The only thing that is changing here is the default encoding when Java serializes a String to bytes and deserializes a String from bytes, which will both now match .NET. The .NET String constructor that takes a byte array still has the problem that Java has now with using the system default charset.