Re: Type cast exception

[Scott Carey]

Try

SpecificDatumReader<LogMessage> din = new 
SpecificDatumReader<LogMessage>(LogMessage.class);

instead of the GenericDatumReader below.


On Apr 26, 2010, at 7:59 AM, Jaydeep Ayachit wrote:

Hello,

I am trying to read from avro data file and want to use specific object (exa 
sample.LogMessage)
The following code gives exception mentioned below. Reader.next() when 
collected in Object/Record, no exception is thrown which is expected.

Any help is appreciated.

public void testMethod5() throws Exception {
            DatumWriter<LogMessage> writer = new 
GenericDatumWriter<LogMessage>(LogMessage.SCHEMA$);
            DataFileWriter<LogMessage> out = new 
DataFileWriter<LogMessage>(writer);

            out.create(LogMessage.SCHEMA$, <File>);
            for (int i = 0; i < 100; i++) {
                  LogMessage msg = new LogMessage();
                  msg.applicationName = new Utf8("app" + i);
                  msg.userid = new Utf8("user" + i);
                  msg.message = new Utf8("this is test log message " + i);

                  out.append(msg);
            }
            out.close();

            DataFileReader<LogMessage> reader;
            GenericDatumReader<LogMessage> din = new 
GenericDatumReader<LogMessage>(LogMessage.SCHEMA$);
            reader = new DataFileReader<LogMessage>(new File(<>), din);

            while (reader.hasNext()) {
                  LogMessage msg = reader.next();
                  System.out.println(msg.toString());
            }
            reader.close();
      }

Exception

java.lang.ClassCastException: org.apache.avro.generic.GenericData$Record cannot 
be cast to sample.LogMessage
      at com.ibm.clas.ReaderWriter.testMethod5(ReaderWriter.java:313)
      at com.ibm.clas.ReaderWriter.main(ReaderWriter.java:322)


Thanks
Jaydeep


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