Package org.apache.beam.sdk.coders

Class SerializableCoder<T extends java.io.Serializable>

  • Type Parameters:
    T - the type of elements handled by this coder
    All Implemented Interfaces:
    java.io.Serializable
    public class SerializableCoder<T extends java.io.Serializable>
extends CustomCoder<T>
    A Coder for Java classes that implement Serializable.

    SerializableCoder should be used only for objects that have proper Object.equals(java.lang.Object) and Object.hashCode() implementations.

    To use, specify the coder type on a PCollection: 

    
 PCollection<MyRecord> records =
     foo.apply(...).setCoder(SerializableCoder.of(MyRecord.class));

    SerializableCoder does not guarantee a deterministic encoding, as Java serialization may produce different binary encodings for two equivalent objects.

    See Also:
    Serialized Form

    • Constructor Detail

      • SerializableCoder

        protected SerializableCoder​(java.lang.Class<T> type,
                            TypeDescriptor<T> typeDescriptor)

    • Method Detail

      • consistentWithEquals

        public boolean consistentWithEquals()
        Description copied from class: Coder
        Returns true if this Coder is injective with respect to Object.equals(java.lang.Object).

        Whenever the encoded bytes of two values are equal, then the original values are equal according to Objects.equals(). Note that this is well-defined for null.

        This condition is most notably false for arrays. More generally, this condition is false whenever equals() compares object identity, rather than performing a semantic/structural comparison.

        By default, returns false.

        Overrides:
        consistentWithEquals in class Coder<T extends java.io.Serializable>

      • structuralValue

        public java.lang.Object structuralValue​(T value)
        The structural value of the object is the object itself. The SerializableCoder should be only used for objects with a proper Object.equals(java.lang.Object) implementation.
        Overrides:
        structuralValue in class Coder<T extends java.io.Serializable>

      • of

        public static <T extends java.io.Serializable> SerializableCoder<T> of​(java.lang.Class<T> clazz)
        Returns a SerializableCoder instance for the provided element class.
        Type Parameters:
        T - the element type

      • getRecordType

        public java.lang.Class<T> getRecordType()

      • encode

        public void encode​(T value,
                   java.io.OutputStream outStream)
            throws java.io.IOException
        Description copied from class: Coder
        Encodes the given value of type T onto the given output stream.
        Specified by:
        encode in class Coder<T extends java.io.Serializable>
        Throws:
        java.io.IOException - if writing to the OutputStream fails for some reason
        CoderException - if the value could not be encoded for some reason

      • decode

        public T decode​(java.io.InputStream inStream)
         throws java.io.IOException,
                CoderException
        Description copied from class: Coder
        Decodes a value of type T from the given input stream in the given context. Returns the decoded value.
        Specified by:
        decode in class Coder<T extends java.io.Serializable>
        Throws:
        java.io.IOException - if reading from the InputStream fails for some reason
        CoderException - if the value could not be decoded for some reason

      • verifyDeterministic

        public void verifyDeterministic()
                         throws Coder.NonDeterministicException
        Throw Coder.NonDeterministicException if the coding is not deterministic.

        In order for a Coder to be considered deterministic, the following must be true:

        • two values that compare as equal (via Object.equals() or Comparable.compareTo(), if supported) have the same encoding.
        • the Coder always produces a canonical encoding, which is the same for an instance of an object even if produced on different computers at different times.
        Overrides:
        verifyDeterministic in class CustomCoder<T extends java.io.Serializable>
        Throws:
        Coder.NonDeterministicException - always. Java serialization is not deterministic with respect to Object.equals(java.lang.Object) for all types.

      • equals

        public boolean equals​(@Nullable java.lang.Object other)
        Overrides:
        equals in class java.lang.Object

      • hashCode

        public int hashCode()
        Overrides:
        hashCode in class java.lang.Object

      • toString

        public java.lang.String toString()
        Overrides:
        toString in class java.lang.Object