com.google.cloud.dataflow.sdk.coders

Annotation Type DefaultCoder

@Documented
 @Retention(value=RUNTIME)
 @Target(value=TYPE)
public @interface DefaultCoder

The DefaultCoder annotation specifies a default Coder class to handle encoding and decoding instances of the annotated class.

The specified Coder must implement a function with the following signature:

 public static Coder<T> of(Class<T> clazz) {...}
 

For example, to configure the use of Java serialization as the default for a class, annotate the class to use SerializableCoder as follows:the

  @DefaultCoder(SerializableCoder.class)
 public class MyCustomDataType {
   // ...
 }
 

Similarly, to configure the use of AvroCoder as the default:

  @DefaultCoder(AvroCoder.class)
 public class MyCustomDataType {
   public MyCustomDataType() {}   // Avro requires an empty constructor.
   // ...
 }
 

Coders specified explicitly via PCollection.setCoder take precedence, followed by Coders registered at runtime via CoderRegistry.registerCoder(java.lang.Class<?>, java.lang.Class<?>).

Required Element Summary

Required Elements

Modifier and Type	Required Element and Description
Class<? extends Coder>	value

Element Detail

value

public abstract Class<? extends Coder> value