Hi Oliver,
oh I missed that one. Thanks!
Setting the FieldDescriptors on the target message wasn't the way to
go. Because the FD contains a lot of information specific to the
enclosing type. I solved the issue by using a reflection based
approach which is not that nice but will work in the beginning.
public static T commandToEvent(Message command,
Class clazz) {
try {
Method m = clazz.getMethod("newBuilder");
Builder builder = (Builder) m.invoke(null);
Map commandFields =
command.getAllFields();
for(Entry e :
commandFields.entrySet()) {
// Construct JavaBean setter for property
String fieldName = e.getKey().getName();
char firstChar =
Character.toUpperCase(fieldName.charAt(0));
String setMethod =
"set"+firstChar+fieldName.substring(1);
// invoke setter with value from the event
message
Method setter =
builder.getClass().getMethod(setMethod,
e.getValue().getClass());
setter.invoke(builder, e.getValue());
}
return (T)builder.build();
} catch (Exception e) {
Throwables.propagate(e);
}
return null;
}
On Wed, Jul 25, 2012 at 1:08 AM, Oliver Jowett wrote:
> On Tue, Jul 24, 2012 at 3:55 PM, Tobias Neef wrote:
>
>> I try to convert the Java representation of a protobuf message into another
>> message with the same fields (ordering, names, types). I try to do it the
>> following way but this ends in a java.lang.InstantiationException:
>>
>> public static T commandToEvent(GeneratedMessage
>> command,
>> Class clazz) {
>> try {
>> Builder builder = clazz.newInstance().newBuilderForType();
>
> Generated message classes don't have a public ctor, so newInstance() will
> fail.
> Pass the default instance of the message class, not the class itself,
> to identify the message type to build?
>
> Oliver
--
You received this message because you are subscribed to the Google Groups
"Protocol Buffers" group.
To post to this group, send email to protobuf@googlegroups.com.
To unsubscribe from this group, send email to
protobuf+unsubscr...@googlegroups.com.
For more options, visit this group at
http://groups.google.com/group/protobuf?hl=en.
