Avro version: 1.7.4 This doesn't work.

avro_issue_2

import java.io.FileOutputStream;
import org.apache.avro.Schema;
import org.apache.avro.file.CodecFactory;
import org.apache.avro.file.DataFileWriter;
import org.apache.avro.generic.GenericDatumReader;
import org.apache.avro.generic.GenericDatumWriter;
import org.apache.avro.io.DecoderFactory;

public class Hrm {
    public static void main(String[] args) {
        try {
            String a = "{\"type\": \"record\", \"namespace\": \"example.avro\", \"name\": \"User\", \"fields\": [{\"type\": \"string\", \"name\": \"name\"}, {\"type\": [\"null\", \"int\"], \"name\": \"favorite_number\"}, {\"type\": [\"null\", \"string\"], \"name\": \"favorite_color\"}]}";
            String b = "{\"name\": \"Alyssa\", \"favorite_number\": null, \"favorite_color\": null}"; //works fine 
        	String c = "{\"name\": \"Alyssa\", \"favorite_number\": 256, \"favorite_color\": \"blue\"}"; //does not work

            Schema avroSchema = new Schema.Parser().parse(a);

            DataFileWriter<Object> writer = new DataFileWriter<Object>(new GenericDatumWriter<Object>(avroSchema));
            writer.setCodec(CodecFactory.deflateCodec(6));
            writer.create(avroSchema, new FileOutputStream("ab_java.avro"));

            GenericDatumReader<Object> reader = new GenericDatumReader<Object>(avroSchema);
            Object datum = reader.read(null, DecoderFactory.get().jsonDecoder(avroSchema, b));
            
            writer.append(datum);
            writer.close();
            
            System.out.println("First successful!");
            
            writer = new DataFileWriter<Object>(new GenericDatumWriter<Object>(avroSchema));
            writer.setCodec(CodecFactory.deflateCodec(6));
            writer.create(avroSchema, new FileOutputStream("ab_java.avro"));

            reader = new GenericDatumReader<Object>(avroSchema);
            datum = reader.read(null, DecoderFactory.get().jsonDecoder(avroSchema, c));
            
            writer.append(datum);
            writer.close();
            
            System.out.println("Second successful!");
        } catch (Exception e) {
            throw new RuntimeException(e);
        }        
    }
}