org.apache.kafka.streams.state

Interface KeyValueStore<K,V>

Type Parameters:

K - The key type

V - The value type

All Superinterfaces:

StateStore

@InterfaceStability.Unstable
public interface KeyValueStore<K,V>
extends StateStore

A key-value store that supports put/get/delete and range queries.

Method Summary

Methods

Modifier and Type	Method and Description
KeyValueIterator<K,V>	all() Return an iterator over all keys in the database.
V	delete(K key) Delete the value from the store (if there is one)
V	get(K key) Get the value corresponding to this key
void	put(K key, V value) Update the value associated with this key
void	putAll(List<KeyValue<K,V>> entries) Update all the given key/value pairs
V	putIfAbsent(K key, V value) Update the value associated with this key, unless a value is already associated with the key
KeyValueIterator<K,V>	range(K from, K to) Get an iterator over a given range of keys.

Methods inherited from interface org.apache.kafka.streams.processor.StateStore

close, flush, init, name, persistent

Method Detail

get

V get(K key)

Get the value corresponding to this key

Parameters:

key - The key to fetch

Returns:

The value or null if no value is found.

Throws:

NullPointerException - If null is used for key.

put

void put(K key,
       V value)

Update the value associated with this key

Parameters:

key - They key to associate the value to

value - The value

Throws:

NullPointerException - If null is used for key or value.

putIfAbsent

V putIfAbsent(K key,
            V value)

Update the value associated with this key, unless a value is already associated with the key

Parameters:

key - They key to associate the value to

value - The value

Returns:

The old value or null if there is no such key.

Throws:

NullPointerException - If null is used for key or value.

putAll

void putAll(List<KeyValue<K,V>> entries)

Update all the given key/value pairs

Parameters:

entries - A list of entries to put into the store.

Throws:

NullPointerException - If null is used for any key or value.

delete

V delete(K key)

Delete the value from the store (if there is one)

Parameters:

key - The key

Returns:

The old value or null if there is no such key.

Throws:

NullPointerException - If null is used for key.

range

KeyValueIterator<K,V> range(K from,
                          K to)

Get an iterator over a given range of keys. This iterator MUST be closed after use.

Parameters:

from - The first key that could be in the range

to - The last key that could be in the range

Returns:

The iterator for this range.

Throws:

NullPointerException - If null is used for from or to.

all

KeyValueIterator<K,V> all()

Return an iterator over all keys in the database. This iterator MUST be closed after use.

Returns:

An iterator of all key/value pairs in the store.