org.apache.flink.api.common.state

Interface MapState<UK,UV>

Type Parameters:

UK - Type of the keys in the state.

UV - Type of the values in the state.

All Superinterfaces:

State

All Known Subinterfaces:

InternalMapState<K,N,UK,UV>

All Known Implementing Classes:

ImmutableMapState

@PublicEvolving
public interface MapState<UK,UV>
extends State

State interface for partitioned key-value state. The key-value pair can be added, updated and retrieved.

The state is accessed and modified by user functions, and checkpointed consistently by the system as part of the distributed snapshots.

The state is only accessible by functions applied on a KeyedStream. The key is automatically supplied by the system, so the function always sees the value mapped to the key of the current element. That way, the system can handle stream and state partitioning consistently together.

Method Summary

Modifier and Type	Method and Description
boolean	contains(UK key) Returns whether there exists the given mapping.
Iterable<Map.Entry<UK,UV>>	entries() Returns all the mappings in the state.
UV	get(UK key) Returns the current value associated with the given key.
boolean	isEmpty() Returns true if this state contains no key-value mappings, otherwise false.
Iterator<Map.Entry<UK,UV>>	iterator() Iterates over all the mappings in the state.
Iterable<UK>	keys() Returns all the keys in the state.
void	put(UK key, UV value) Associates a new value with the given key.
void	putAll(Map<UK,UV> map) Copies all of the mappings from the given map into the state.
void	remove(UK key) Deletes the mapping of the given key.
Iterable<UV>	values() Returns all the values in the state.

Methods inherited from interface org.apache.flink.api.common.state.State

clear

Method Detail

get

UV get(UK key)
throws Exception

Returns the current value associated with the given key.

Parameters:

key - The key of the mapping

Returns:

The value of the mapping with the given key

Throws:

Exception - Thrown if the system cannot access the state.

put

void put(UK key,
         UV value)
  throws Exception

Associates a new value with the given key.

Parameters:

key - The key of the mapping

value - The new value of the mapping

Throws:

Exception - Thrown if the system cannot access the state.

putAll

void putAll(Map<UK,UV> map)
     throws Exception

Copies all of the mappings from the given map into the state.

Parameters:

map - The mappings to be stored in this state

Throws:

Exception - Thrown if the system cannot access the state.

remove

void remove(UK key)
     throws Exception

Deletes the mapping of the given key.

Parameters:

key - The key of the mapping

Throws:

Exception - Thrown if the system cannot access the state.

contains

boolean contains(UK key)
          throws Exception

Returns whether there exists the given mapping.

Parameters:

key - The key of the mapping

Returns:

True if there exists a mapping whose key equals to the given key

Throws:

Exception - Thrown if the system cannot access the state.

entries

Iterable<Map.Entry<UK,UV>> entries()
                            throws Exception

Returns all the mappings in the state.

Returns:

An iterable view of all the key-value pairs in the state.

Throws:

Exception - Thrown if the system cannot access the state.

keys

Iterable<UK> keys()
           throws Exception

Returns all the keys in the state.

Returns:

An iterable view of all the keys in the state.

Throws:

Exception - Thrown if the system cannot access the state.

values

Iterable<UV> values()
             throws Exception

Returns all the values in the state.

Returns:

An iterable view of all the values in the state.

Throws:

Exception - Thrown if the system cannot access the state.

iterator

Iterator<Map.Entry<UK,UV>> iterator()
                             throws Exception

Iterates over all the mappings in the state.

Returns:

An iterator over all the mappings in the state

Throws:

Exception - Thrown if the system cannot access the state.

isEmpty

boolean isEmpty()
         throws Exception

Returns true if this state contains no key-value mappings, otherwise false.

Returns:

True if this state contains no key-value mappings, otherwise false.

Throws:

Exception - Thrown if the system cannot access the state.