CoderFactories (Google Cloud Dataflow SDK 1.9.1 API)

Google Cloud Dataflow SDK for Java, version 1.9.1

com.google.cloud.dataflow.sdk.coders

Class CoderFactories


  • public final class CoderFactories
extends Object
    Static utility methods for creating and working with Coders.

    • Method Detail

      • fromStaticMethods

        public static <T> CoderFactory fromStaticMethods(Class<T> clazz)
        Creates a CoderFactory built from particular static methods of a class that implements Coder.

        The class must have the following static methods:

        • public static Coder<T> of(Coder<X> argCoder1, Coder<Y> argCoder2, ...)
        • public static List<Object> getInstanceComponents(T exampleValue);

        The of(...) method will be used to construct a Coder<T> from component Coders. It must accept one Coder argument for each generic type parameter of T. If T takes no generic type parameters, then the of() factory method should take no arguments.

        The getInstanceComponents method will be used to decompose a value during the Coder inference process, to automatically choose coders for the components.

        Note that the class T to be coded may be a not-yet-specialized generic class. For a generic class MyClass<X> and an actual type parameter Foo, the CoderFactoryFromStaticMethods will accept any Coder<Foo> and produce a Coder<MyClass<Foo>>.

        For example, the CoderFactory returned by fromStaticMethods(ListCoder.class) will produce a Coder<List<X>> for any Coder Coder<X>.

      • forCoder

        public static <T> CoderFactory forCoder(Coder<T> coder)
        Creates a CoderFactory that always returns the given coder.

        The getInstanceComponents method of this CoderFactory always returns an empty list.