java.lang.Object
- org.apache.flink.api.common.state.StateDescriptor<S,T>

Type Parameters:

S - The type of the State objects created from this StateDescriptor.

T - The type of the value of the state object described by this state descriptor.

All Implemented Interfaces:

Serializable

Direct Known Subclasses:

AggregatingStateDescriptor, ListStateDescriptor, MapStateDescriptor, ReducingStateDescriptor, ValueStateDescriptor
```
@PublicEvolving
public abstract class StateDescriptor<S extends State,T>
extends Object
implements Serializable
```
Base class for state descriptors. A StateDescriptor is used for creating partitioned State in stateful operations.
Subclasses must correctly implement equals(Object) and hashCode().

See Also:

Serialized Form

Nested Class Summary

Nested Classes
Modifier and Type Class Description

static class StateDescriptor.Type
An enumeration of the types of supported states.

Field Summary

Fields
Modifier and Type	Field	Description
`protected T`	`defaultValue`	Deprecated. To make the semantics more clear, user should manually manage the default value if the contents of the state is `null`
`protected String`	`name`	Name that uniquely identifies state created from this StateDescriptor.

Constructor Summary

Constructors
Modifier	Constructor	Description
`protected`	`StateDescriptor(String name, Class<T> type, T defaultValue)`	Create a new `StateDescriptor` with the given name and the given type information.
`protected`	`StateDescriptor(String name, TypeInformation<T> typeInfo, T defaultValue)`	Create a new `StateDescriptor` with the given name and the given type information.
`protected`	`StateDescriptor(String name, TypeSerializer<T> serializer, T defaultValue)`	Create a new `StateDescriptor` with the given name and the given type serializer.

Method Summary

All Methods Instance Methods Abstract Methods Concrete Methods Deprecated Methods
Modifier and Type	Method	Description
`void`	`enableTimeToLive(StateTtlConfig ttlConfig)`	Configures optional activation of state time-to-live (TTL).
`boolean`	`equals(Object o)`
`T`	`getDefaultValue()`	Returns the default value.
`String`	`getName()`	Returns the name of this `StateDescriptor`.
`String`	`getQueryableStateName()`	Deprecated. The Queryable State feature is deprecated since Flink 1.18, and will be removed in a future Flink major version.
`TypeSerializer<T>`	`getSerializer()`	Returns the `TypeSerializer` that can be used to serialize the value in the state.
`StateTtlConfig`	`getTtlConfig()`
`abstract StateDescriptor.Type`	`getType()`
`int`	`hashCode()`
`void`	`initializeSerializerUnlessSet(ExecutionConfig executionConfig)`	Initializes the serializer, unless it has been initialized before.
`boolean`	`isQueryable()`	Deprecated. The Queryable State feature is deprecated since Flink 1.18, and will be removed in a future Flink major version.
`boolean`	`isSerializerInitialized()`	Checks whether the serializer has been initialized.
`void`	`setQueryable(String queryableStateName)`	Deprecated. The Queryable State feature is deprecated since Flink 1.18, and will be removed in a future Flink major version.
`String`	`toString()`

Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait

- Field Detail
  - name
```
protected final String name
```
    Name that uniquely identifies state created from this StateDescriptor.
  - defaultValue
```
@Nullable
@Deprecated
protected transient T defaultValue
```
    Deprecated.
    To make the semantics more clear, user should manually manage the default value if the contents of the state is null
    
    The default value returned by the state when no other value is bound to a key.
- Constructor Detail
  - StateDescriptor
```
protected StateDescriptor(String name,
                          TypeSerializer<T> serializer,
                          @Nullable
                          T defaultValue)
```
    Create a new StateDescriptor with the given name and the given type serializer.
    
    Parameters:
    
    name - The name of the StateDescriptor.
    
    serializer - The type serializer for the values in the state.
    
    defaultValue - The default value that will be set when requesting state without setting a value before.
  - StateDescriptor
```
protected StateDescriptor(String name,
                          TypeInformation<T> typeInfo,
                          @Nullable
                          T defaultValue)
```
    Create a new StateDescriptor with the given name and the given type information.
    
    Parameters:
    
    name - The name of the StateDescriptor.
    
    typeInfo - The type information for the values in the state.
    
    defaultValue - The default value that will be set when requesting state without setting a value before.
  - StateDescriptor
```
protected StateDescriptor(String name,
                          Class<T> type,
                          @Nullable
                          T defaultValue)
```
    Create a new StateDescriptor with the given name and the given type information.
    If this constructor fails (because it is not possible to describe the type via a class), consider using the StateDescriptor(String, TypeInformation, Object) constructor.
    
    Parameters:
    
    name - The name of the StateDescriptor.
    
    type - The class of the type of values in the state.
    
    defaultValue - The default value that will be set when requesting state without setting a value before.
- Method Detail
  - getName
```
public String getName()
```
    Returns the name of this StateDescriptor.
  - getDefaultValue
```
public T getDefaultValue()
```
    Returns the default value.
  - getSerializer
```
public TypeSerializer<T> getSerializer()
```
    Returns the TypeSerializer that can be used to serialize the value in the state. Note that the serializer may initialized lazily and is only guaranteed to exist after calling initializeSerializerUnlessSet(ExecutionConfig).
  - setQueryable
```
@Deprecated
public void setQueryable(String queryableStateName)
```
    Deprecated.
    The Queryable State feature is deprecated since Flink 1.18, and will be removed in a future Flink major version.
    
    Sets the name for queries of state created from this descriptor.
    If a name is set, the created state will be published for queries during runtime. The name needs to be unique per job. If there is another state instance published under the same name, the job will fail during runtime.
    
    Parameters:
    
    queryableStateName - State name for queries (unique name per job)
    
    Throws:
    
    IllegalStateException - If queryable state name already set
  - getQueryableStateName
```
@Nullable
@Deprecated
public String getQueryableStateName()
```
    Deprecated.
    The Queryable State feature is deprecated since Flink 1.18, and will be removed in a future Flink major version.
    
    Returns the queryable state name.
    
    Returns:
    
    Queryable state name or null if not set.
  - isQueryable
```
@Deprecated
public boolean isQueryable()
```
    Deprecated.
    The Queryable State feature is deprecated since Flink 1.18, and will be removed in a future Flink major version.
    
    Returns whether the state created from this descriptor is queryable.
    
    Returns:
    
    true if state is queryable, false otherwise.
  - enableTimeToLive
```
public void enableTimeToLive(StateTtlConfig ttlConfig)
```
    Configures optional activation of state time-to-live (TTL).
    State user value will expire, become unavailable and be cleaned up in storage depending on configured StateTtlConfig.
    If enabling the TTL configuration, the field defaultValue will be invalid.
    
    Parameters:
    
    ttlConfig - configuration of state TTL
  - getTtlConfig
```
@Nonnull
@Internal
public StateTtlConfig getTtlConfig()
```
  - isSerializerInitialized
```
public boolean isSerializerInitialized()
```
    Checks whether the serializer has been initialized. Serializer initialization is lazy, to allow parametrization of serializers with an ExecutionConfig via initializeSerializerUnlessSet(ExecutionConfig).
    
    Returns:
    
    True if the serializers have been initialized, false otherwise.
  - initializeSerializerUnlessSet
```
public void initializeSerializerUnlessSet(ExecutionConfig executionConfig)
```
    Initializes the serializer, unless it has been initialized before.
    
    Parameters:
    
    executionConfig - The execution config to use when creating the serializer.
  - hashCode
```
public final int hashCode()
```
    Overrides:
    
    hashCode in class Object
  - equals
```
public final boolean equals(Object o)
```
    Overrides:
    
    equals in class Object
  - toString
```
public String toString()
```
    Overrides:
    
    toString in class Object
  - getType
```
public abstract StateDescriptor.Type getType()
```

Class StateDescriptor<S extends State,​T>

Nested Class Summary

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

name

defaultValue

Constructor Detail

StateDescriptor

StateDescriptor

StateDescriptor

Method Detail

getName

getDefaultValue

getSerializer

setQueryable

getQueryableStateName

isQueryable

enableTimeToLive

getTtlConfig

isSerializerInitialized

initializeSerializerUnlessSet

hashCode

equals

toString

getType

Class StateDescriptor<S extends State,T>