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 satisfy the requirements of CoderProviders.fromStaticMethods(java.lang.Class<T>). Two classes provided by the SDK that are intended for use with this annotation include SerializableCoder and AvroCoder.

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

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

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(com.google.cloud.dataflow.sdk.coders.Coder<T>) take precedence, followed by Coders registered at runtime via CoderRegistry.registerCoder(java.lang.Class<?>, java.lang.Class<?>). See CoderRegistry for a more detailed discussion of the precedence rules.

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