Package 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

      All Methods Instance Methods Abstract Methods 
      Modifier and Type Method 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.