MapState

Type Parameters:

K - the type of keys maintained by this map

V - the type of mapped values

All Superinterfaces:

State
```
@Experimental(value=STATE)
public interface MapState<K,V>
extends State
```
A ReadableState cell mapping keys to values.
Implementations of this form of state are expected to implement map operations efficiently as supported by some associated backing key-value store.

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method and Description
`ReadableState<java.lang.Iterable<java.util.Map.Entry<K,V>>>`	`entries()` Returns an `Iterable` over the key-value pairs contained in this map.
`ReadableState<V>`	`get(K key)` A deferred lookup.
`ReadableState<java.lang.Iterable<K>>`	`keys()` Returns an `Iterable` over the keys contained in this map.
`void`	`put(K key, V value)` Associates the specified value with the specified key in this state.
`ReadableState<V>`	`putIfAbsent(K key, V value)` A deferred read-followed-by-write.
`void`	`remove(K key)` Remove the mapping for a key from this map if it is present.
`ReadableState<java.lang.Iterable<V>>`	`values()` Returns an `Iterable` over the values contained in this map.

Methods inherited from interface org.apache.beam.sdk.state.State
clear

- Method Detail
  - put
```
void put(K key,
         V value)
```
    Associates the specified value with the specified key in this state.
    Changes will not be reflected in the results returned by previous calls to ReadableState.read() on the results any of the reading methods (get(K), keys(), values(), and entries()).
  - putIfAbsent
```
ReadableState<V> putIfAbsent(K key,
                             V value)
```
    A deferred read-followed-by-write.
    When read() is called on the result or state is committed, it forces a read of the map and reconciliation with any pending modifications.
    If the specified key is not already associated with a value (or is mapped to null) associates it with the given value and returns null, else returns the current value.
    Changes will not be reflected in the results returned by previous calls to ReadableState.read() on the results any of the reading methods (get(K), keys(), values(), and entries()).
  - remove
```
void remove(K key)
```
    Remove the mapping for a key from this map if it is present.
    Changes will not be reflected in the results returned by previous calls to ReadableState.read() on the results any of the reading methods (get(K), keys(), values(), and entries()).
  - get
```
ReadableState<V> get(K key)
```
    A deferred lookup.
    A user is encouraged to call get for all relevant keys and call readLater() on the results.
    When read() is called, a particular state implementation is encouraged to perform all pending reads in a single batch.
  - keys
```
ReadableState<java.lang.Iterable<K>> keys()
```
    Returns an Iterable over the keys contained in this map.
  - values
```
ReadableState<java.lang.Iterable<V>> values()
```
    Returns an Iterable over the values contained in this map.
  - entries
```
ReadableState<java.lang.Iterable<java.util.Map.Entry<K,V>>> entries()
```
    Returns an Iterable over the key-value pairs contained in this map.

Interface MapState<K,V>

Method Summary

Methods inherited from interface org.apache.beam.sdk.state.State

Method Detail

put

putIfAbsent

remove

get

keys

values

entries