org.apache.beam.sdk.values

Class TypeDescriptors

java.lang.Object

org.apache.beam.sdk.values.TypeDescriptors

public class TypeDescriptors
extends java.lang.Object

A utility class for creating TypeDescriptor objects for different types, such as Java primitive types, containers and KVs of other TypeDescriptor objects, and extracting type variables of parameterized types (e.g. extracting the OutputT type variable of a DoFn<InputT, OutputT>).

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	TypeDescriptors.TypeVariableExtractor<InputT,OutputT> A helper interface for use with extractFromTypeParameters(Object, Class, TypeVariableExtractor).

Constructor Summary

Constructors

Constructor and Description
TypeDescriptors()

Method Summary

Modifier and Type	Method and Description
static TypeDescriptor<java.math.BigDecimal>	bigdecimals() The TypeDescriptor for BigDecimal.
static TypeDescriptor<java.math.BigInteger>	bigintegers() The TypeDescriptor for BigInteger.
static TypeDescriptor<java.lang.Boolean>	booleans() The TypeDescriptor for Boolean.
static TypeDescriptor<java.lang.Byte>	bytes() The TypeDescriptor for Byte.
static TypeDescriptor<java.lang.Character>	characters() The TypeDescriptor for Character.
static TypeDescriptor<java.lang.Double>	doubles() The TypeDescriptor for Double.
static <T,V> TypeDescriptor<V>	extractFromTypeParameters(T instance, java.lang.Class<? super T> supertype, TypeDescriptors.TypeVariableExtractor<T,V> extractor) Extracts a type from the actual type parameters of a parameterized class, subject to Java type erasure.
static <T,V> TypeDescriptor<V>	extractFromTypeParameters(TypeDescriptor<T> type, java.lang.Class<? super T> supertype, TypeDescriptors.TypeVariableExtractor<T,V> extractor) Like extractFromTypeParameters(Object, Class, TypeVariableExtractor), but takes a TypeDescriptor of the instance being analyzed rather than the instance itself.
static TypeDescriptor<java.lang.Float>	floats() The TypeDescriptor for Float.
static <InputT,OutputT> TypeDescriptor<InputT>	inputOf(Contextful.Fn<InputT,OutputT> fn) Like inputOf(ProcessFunction) but for Contextful.Fn.
static <InputT,OutputT> TypeDescriptor<InputT>	inputOf(ProcessFunction<InputT,OutputT> fn) Returns a type descriptor for the input of the given ProcessFunction, subject to Java type erasure: may contain unresolved type variables if the type was erased.
static <InputT,OutputT> TypeDescriptor<InputT>	inputOf(SerializableFunction<InputT,OutputT> fn) Binary compatibility adapter for inputOf(ProcessFunction).
static TypeDescriptor<java.lang.Integer>	integers() The TypeDescriptor for Integer.
static <T> TypeDescriptor<java.lang.Iterable<T>>	iterables(TypeDescriptor<T> iterable) The TypeDescriptor for Iterable.
static <K,V> TypeDescriptor<KV<K,V>>	kvs(TypeDescriptor<K> key, TypeDescriptor<V> value) The TypeDescriptor for KV.
static <T> TypeDescriptor<java.util.List<T>>	lists(TypeDescriptor<T> element) The TypeDescriptor for List.
static TypeDescriptor<java.lang.Long>	longs() The TypeDescriptor for Long.
static <K,V> TypeDescriptor<java.util.Map<K,V>>	maps(TypeDescriptor<K> keyType, TypeDescriptor<V> valueType) The TypeDescriptor for Map.
static TypeDescriptor<java.lang.Void>	nulls() The TypeDescriptor for nulls/Void.
static <InputT,OutputT> TypeDescriptor<OutputT>	outputOf(Contextful.Fn<InputT,OutputT> fn) Like outputOf(ProcessFunction) but for Contextful.Fn.
static <InputT,OutputT> TypeDescriptor<OutputT>	outputOf(ProcessFunction<InputT,OutputT> fn) Returns a type descriptor for the output of the given ProcessFunction, subject to Java type erasure: may contain unresolved type variables if the type was erased.
static <InputT,OutputT> TypeDescriptor<OutputT>	outputOf(SerializableFunction<InputT,OutputT> fn) Binary compatibility adapter for outputOf(ProcessFunction).
static TypeDescriptor<Row>	rows() The TypeDescriptor for Row.
static <T> TypeDescriptor<java.util.Set<T>>	sets(TypeDescriptor<T> element) The TypeDescriptor for Set.
static TypeDescriptor<java.lang.Short>	shorts() The TypeDescriptor for Short.
static TypeDescriptor<java.lang.String>	strings() The TypeDescriptor for String.
static TypeDescriptor<java.lang.Void>	voids()

Methods inherited from class java.lang.Object

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

Constructor Detail

TypeDescriptors

public TypeDescriptors()

Method Detail

booleans

public static TypeDescriptor<java.lang.Boolean> booleans()

The TypeDescriptor for Boolean. This is the equivalent of:

 new TypeDescriptor<Boolean>() {};
 

Returns:

A TypeDescriptor for Boolean

doubles

public static TypeDescriptor<java.lang.Double> doubles()

The TypeDescriptor for Double. This is the equivalent of:

 new TypeDescriptor<Double>() {};
 

Returns:

A TypeDescriptor for Double

floats

public static TypeDescriptor<java.lang.Float> floats()

The TypeDescriptor for Float. This is the equivalent of:

 new TypeDescriptor<Float>() {};
 

Returns:

A TypeDescriptor for Float

integers

public static TypeDescriptor<java.lang.Integer> integers()

The TypeDescriptor for Integer. This is the equivalent of:

 new TypeDescriptor<Integer>() {};
 

Returns:

A TypeDescriptor for Integer

longs

public static TypeDescriptor<java.lang.Long> longs()

The TypeDescriptor for Long. This is the equivalent of:

 new TypeDescriptor<Long>() {};
 

Returns:

A TypeDescriptor for Long

shorts

public static TypeDescriptor<java.lang.Short> shorts()

The TypeDescriptor for Short. This is the equivalent of:

 new TypeDescriptor<Short>() {};
 

Returns:

A TypeDescriptor for Short

bigdecimals

public static TypeDescriptor<java.math.BigDecimal> bigdecimals()

The TypeDescriptor for BigDecimal. This is the equivalent of:

 new TypeDescriptor<BigDecimal>() {};
 

Returns:

A TypeDescriptor for BigDecimal

bigintegers

public static TypeDescriptor<java.math.BigInteger> bigintegers()

The TypeDescriptor for BigInteger. This is the equivalent of:

 new TypeDescriptor<BigInteger>() {};
 

Returns:

A TypeDescriptor for BigInteger

rows

public static TypeDescriptor<Row> rows()

The TypeDescriptor for Row. This is the equivalent of:

 new TypeDescriptor<Row>() {};
 

Returns:

A TypeDescriptor for Row

strings

public static TypeDescriptor<java.lang.String> strings()

The TypeDescriptor for String. This is the equivalent of:

 new TypeDescriptor<String>() {};
 

Returns:

A TypeDescriptor for String

characters

public static TypeDescriptor<java.lang.Character> characters()

The TypeDescriptor for Character. This is the equivalent of:

 new TypeDescriptor<Character>() {};
 

Returns:

A TypeDescriptor for Character

bytes

public static TypeDescriptor<java.lang.Byte> bytes()

The TypeDescriptor for Byte. This is the equivalent of:

 new TypeDescriptor<Byte>() {};
 

Returns:

A TypeDescriptor for Byte

nulls

public static TypeDescriptor<java.lang.Void> nulls()

The TypeDescriptor for nulls/Void. This is the equivalent of:

 new TypeDescriptor<Void>() {};
 

Returns:

A TypeDescriptor for nulls/Void

kvs

public static <K,V> TypeDescriptor<KV<K,V>> kvs(TypeDescriptor<K> key,
                                                TypeDescriptor<V> value)

The TypeDescriptor for KV. This is the equivalent of:

 new TypeDescriptor<KV<K,V>>() {};
 

Example of use:

 PCollection<String> words = ...;
 PCollection<KV<String, String>> words = words.apply(FlatMapElements
         .into(TypeDescriptors.kv(TypeDescriptors.strings(), TypeDescriptors.strings()))
         .via(...));
 

Parameters:

key - The TypeDescriptor for the key

value - The TypeDescriptor for the value

Returns:

A TypeDescriptor for KV

sets

public static <T> TypeDescriptor<java.util.Set<T>> sets(TypeDescriptor<T> element)

The TypeDescriptor for Set. This is the equivalent of:

 new TypeDescriptor<Set<E>>() {};
 

Example of use:

 PCollection<String> words = ...;
 PCollection<Set<String>> words = words.apply(FlatMapElements
         .into(TypeDescriptors.sets(TypeDescriptors.strings()))
         .via(...));
 

Parameters:

element - The TypeDescriptor for the set

Returns:

A TypeDescriptor for Set

maps

public static <K,V> TypeDescriptor<java.util.Map<K,V>> maps(TypeDescriptor<K> keyType,
                                                            TypeDescriptor<V> valueType)

The TypeDescriptor for Map.

lists

public static <T> TypeDescriptor<java.util.List<T>> lists(TypeDescriptor<T> element)

The TypeDescriptor for List. This is the equivalent of:

 new TypeDescriptor<List<E>>() {};
 

Example of use:

 PCollection<String> words = ...;
 PCollection<List<String>> words = words.apply(FlatMapElements
         .into(TypeDescriptors.lists(TypeDescriptors.strings()))
         .via(...));
 

Parameters:

element - The TypeDescriptor for the list

Returns:

A TypeDescriptor for List

iterables

public static <T> TypeDescriptor<java.lang.Iterable<T>> iterables(TypeDescriptor<T> iterable)

The TypeDescriptor for Iterable. This is the equivalent of:

 new TypeDescriptor<Iterable<E>>() {};
 

Example of use:

 PCollection<String> words = ...;
 PCollection<Iterable<String>> words = words.apply(FlatMapElements
         .into(TypeDescriptors.iterables(TypeDescriptors.strings()))
         .via(...));
 

Parameters:

iterable - The TypeDescriptor for the iterable

Returns:

A TypeDescriptor for Iterable

voids

public static TypeDescriptor<java.lang.Void> voids()

extractFromTypeParameters

public static <T,V> TypeDescriptor<V> extractFromTypeParameters(T instance,
                                                                java.lang.Class<? super T> supertype,
                                                                TypeDescriptors.TypeVariableExtractor<T,V> extractor)

Extracts a type from the actual type parameters of a parameterized class, subject to Java type erasure. The type to extract is specified in a way that is safe w.r.t. changing the type signature of the parameterized class, as opposed to specifying the name or index of a type variable.

Example of use:

 class Foo<BarT> {
   private ProcessFunction<BarT, String> fn;

   TypeDescriptor<BarT> inferBarTypeDescriptorFromFn() {
     return TypeDescriptors.extractFromTypeParameters(
       fn,
       ProcessFunction.class,
       // The actual type of "fn" is matched against the input type of the extractor,
       // and the obtained values of type variables of the superclass are substituted
       // into the output type of the extractor.
       new TypeVariableExtractor<ProcessFunction<BarT, String>, BarT>() {});
   }
 }
 

Parameters:

instance - The object being analyzed

supertype - Parameterized superclass of interest

extractor - A class for specifying the type to extract from the supertype

Returns:

A TypeDescriptor for the actual value of the result type of the extractor, potentially containing unresolved type variables if the type was erased.

extractFromTypeParameters

public static <T,V> TypeDescriptor<V> extractFromTypeParameters(TypeDescriptor<T> type,
                                                                java.lang.Class<? super T> supertype,
                                                                TypeDescriptors.TypeVariableExtractor<T,V> extractor)

Like extractFromTypeParameters(Object, Class, TypeVariableExtractor), but takes a TypeDescriptor of the instance being analyzed rather than the instance itself.

inputOf

public static <InputT,OutputT> TypeDescriptor<InputT> inputOf(ProcessFunction<InputT,OutputT> fn)

Returns a type descriptor for the input of the given ProcessFunction, subject to Java type erasure: may contain unresolved type variables if the type was erased.

inputOf

public static <InputT,OutputT> TypeDescriptor<InputT> inputOf(SerializableFunction<InputT,OutputT> fn)

Binary compatibility adapter for inputOf(ProcessFunction).

outputOf

public static <InputT,OutputT> TypeDescriptor<OutputT> outputOf(ProcessFunction<InputT,OutputT> fn)

Returns a type descriptor for the output of the given ProcessFunction, subject to Java type erasure: may contain unresolved type variables if the type was erased.

outputOf

public static <InputT,OutputT> TypeDescriptor<OutputT> outputOf(SerializableFunction<InputT,OutputT> fn)

Binary compatibility adapter for outputOf(ProcessFunction).

inputOf

public static <InputT,OutputT> TypeDescriptor<InputT> inputOf(Contextful.Fn<InputT,OutputT> fn)

Like inputOf(ProcessFunction) but for Contextful.Fn.

outputOf

public static <InputT,OutputT> TypeDescriptor<OutputT> outputOf(Contextful.Fn<InputT,OutputT> fn)

Like outputOf(ProcessFunction) but for Contextful.Fn.