Hadoop: Easy way to have object as output value without Writable interface
You can define your own serialization mechanism
- http://www.lexemetech.com/2008/07/rpc-and-serialization-with-hadoop.html
- https://issues.apache.org/jira/browse/HADOOP-1986
I think it resolves around implementing the Serialization interface, and defining your implementation in the io.serializations configuration property
In your case, if you just want to use java serialization, set this property to:
org.apache.hadoop.io.serializer.JavaSerialization