java - Implementing a MessageBodyReader for an enum -

i trying implement new messagebodyreader/writer combination, having trouble reader part. given following declaration

public class jsr367enumprovider<t extends enum> implements                                                 messagebodyreader<t>,                                                 messagebodywriter<t> 

works there's warning saying enum raw. fix tried put in enum<?>

however yield error in readfrom method

@override public t readfrom(final class<t> type,     final type generictype,     final annotation[] annotations,     final mediatype mediatype,     final multivaluedmap<string, string> httpheaders,     final inputstream inputstream) throws ioexception,         webapplicationexception {      // todo support other encodings using http header     try (scanner s = new scanner(inputstream).usedelimiter("\\a")) {         return (t) enum.valueof(type, s.next());     }  } 

which warns of unchecked cast. there way around without resorting @supresswarnings?

no, there's not. recall signature of method you're trying cast:

enum.valueof(class<t> enumtype, string name)

strictly speaking on code you've provided, cannot rid of warning. suppress it, follow practices, such what's prescribed in effective java 2nd edition: item 24: eliminate unchecked warnings:

• eliminate every unchecked warning can.
• if can't eliminate warning, , can prove code provoked warning typesafe, (and then) suppress warning @suppresswarning("unchecked") annotation.
• always use suppresswarning annotation on smallest scope possible.
• every time use @suppresswarning("unchecked") annotation, add comment saying why it's safe so.