View.AsSingleton (Google Cloud Dataflow SDK 1.9.1 API)

Google Cloud Dataflow SDK for Java, version 1.9.1

Warning: Cloud Dataflow SDK 1.x for Java is unsupported as of October 16, 2018. See Migrating from Cloud Dataflow SDK 1.x for Java for migration guidance.

Note: If you are using Cloud Dataflow SDK version 2.x, see the Apache Beam API reference documentation.

com.google.cloud.dataflow.sdk.transforms

Class View.AsSingleton<T>

• java.lang.Object
• • com.google.cloud.dataflow.sdk.transforms.PTransform<PCollection<T>,PCollectionView<T>>
  • • com.google.cloud.dataflow.sdk.transforms.View.AsSingleton<T>

• All Implemented Interfaces:

  HasDisplayData, Serializable

  Enclosing class:

  View

  ---

  
  

  public static class View.AsSingleton<T>
  extends PTransform<PCollection<T>,PCollectionView<T>>

  Not intended for direct use by pipeline authors; public only so a PipelineRunner may override its behavior.

  See View.asSingleton().

  See Also:

  Serialized Form

• • Field Summary

    • Fields inherited from class com.google.cloud.dataflow.sdk.transforms.PTransform

      name

  • Method Summary

    All Methods Instance Methods Concrete Methods 

    Modifier and Type	Method and Description
    PCollectionView<T>	apply(PCollection<T> input) Applies this PTransform on the given InputT, and returns its Output.
    T	defaultValue() Returns the default value of this transform, or null if there isn't one.
    boolean	hasDefaultValue() Returns whether this transform has a default value.
    void	validate(PCollection<T> input) Called before invoking apply (which may be intercepted by the runner) to verify this transform is fully specified and applicable to the specified input.
    View.AsSingleton<T>	withDefaultValue(T defaultValue) Default value to return for windows with no value in them.

    • Methods inherited from class com.google.cloud.dataflow.sdk.transforms.PTransform

      getDefaultOutputCoder, getDefaultOutputCoder, getDefaultOutputCoder, getKindString, getName, populateDisplayData, toString

    • Methods inherited from class java.lang.Object

      clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

• • Method Detail

    • hasDefaultValue

      public boolean hasDefaultValue()

      Returns whether this transform has a default value.

    • defaultValue

      public T defaultValue()

      Returns the default value of this transform, or null if there isn't one.

    • withDefaultValue

      public View.AsSingleton<T> withDefaultValue(T defaultValue)

      Default value to return for windows with no value in them.

    • validate

      public void validate(PCollection<T> input)

      Description copied from class: PTransform
      Called before invoking apply (which may be intercepted by the runner) to verify this transform is fully specified and applicable to the specified input.

      By default, does nothing.

      Overrides:

      validate in class PTransform<PCollection<T>,PCollectionView<T>>

    • apply

      public PCollectionView<T> apply(PCollection<T> input)

      Description copied from class: PTransform
      Applies this PTransform on the given InputT, and returns its Output.

      Composite transforms, which are defined in terms of other transforms, should return the output of one of the composed transforms. Non-composite transforms, which do not apply any transforms internally, should return a new unbound output and register evaluators (via backend-specific registration methods).

      The default implementation throws an exception. A derived class must either implement apply, or else each runner must supply a custom implementation via PipelineRunner.apply(com.google.cloud.dataflow.sdk.transforms.PTransform<InputT, OutputT>, InputT).

      Overrides:

      apply in class PTransform<PCollection<T>,PCollectionView<T>>