Package org.apache.flink.api.common.state

Class ListStateDescriptor<T>

java.lang.Object

org.apache.flink.api.common.state.StateDescriptor<ListState<T>,List<T>>

org.apache.flink.api.common.state.ListStateDescriptor<T>

Type Parameters:

T - The type of the values that can be added to the list state.

All Implemented Interfaces:

Serializable

@PublicEvolving
public class ListStateDescriptor<T>
extends StateDescriptor<ListState<T>,List<T>>

A StateDescriptor for ListState. This can be used to create state where the type is a list that can be appended and iterated over.

Using ListState is typically more efficient than manually maintaining a list in a ValueState, because the backing implementation can support efficient appends, rather than replacing the full list on write.

To create keyed list state (on a KeyedStream), use RuntimeContext.getListState(ListStateDescriptor).

See Also:

Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from class org.apache.flink.api.common.state.StateDescriptor

StateDescriptor.Type

Field Summary

Fields inherited from class org.apache.flink.api.common.state.StateDescriptor

defaultValue, name

Constructor Summary

Constructors

Constructor	Description
ListStateDescriptor(String name, Class<T> elementTypeClass)	Creates a new ListStateDescriptor with the given name and list element type.
ListStateDescriptor(String name, TypeInformation<T> elementTypeInfo)	Creates a new ListStateDescriptor with the given name and list element type.
ListStateDescriptor(String name, TypeSerializer<T> typeSerializer)	Creates a new ListStateDescriptor with the given name and list element type.

Method Summary

Modifier and Type	Method	Description
TypeSerializer<T>	getElementSerializer()	Gets the serializer for the elements contained in the list.
StateDescriptor.Type	getType()

Methods inherited from class org.apache.flink.api.common.state.StateDescriptor

enableTimeToLive, equals, getDefaultValue, getName, getQueryableStateName, getSerializer, getTtlConfig, hashCode, initializeSerializerUnlessSet, initializeSerializerUnlessSet, isQueryable, isSerializerInitialized, setQueryable, toString

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

ListStateDescriptor

public ListStateDescriptor(String name,
                           Class<T> elementTypeClass)

Creates a new ListStateDescriptor with the given name and list element type.

If this constructor fails (because it is not possible to describe the type via a class), consider using the ListStateDescriptor(String, TypeInformation) constructor.

Parameters:

name - The (unique) name for the state.

elementTypeClass - The type of the elements in the state.

ListStateDescriptor

public ListStateDescriptor(String name,
                           TypeInformation<T> elementTypeInfo)

Creates a new ListStateDescriptor with the given name and list element type.

Parameters:

name - The (unique) name for the state.

elementTypeInfo - The type of the elements in the state.

ListStateDescriptor

public ListStateDescriptor(String name,
                           TypeSerializer<T> typeSerializer)

Creates a new ListStateDescriptor with the given name and list element type.

Parameters:

name - The (unique) name for the state.

typeSerializer - The type serializer for the list values.

Method Detail

getElementSerializer

public TypeSerializer<T> getElementSerializer()

Gets the serializer for the elements contained in the list.

Returns:

The serializer for the elements in the list.

getType

public StateDescriptor.Type getType()

Specified by:

getType in class StateDescriptor<ListState<T>,List<T>>