io.vertx.core.shareddata

Interface LocalMap<K,V>

public interface LocalMap<K,V>

Local maps can be used to share data safely in a single Vert.x instance.

The map only allows immutable keys and values in the map, OR certain mutable objects such as Buffer instances which will be copied when they are added to the map.

This ensures there is no shared access to mutable state from different threads (e.g. different event loops) in the Vert.x instance, and means you don't have to protect access to that state using synchronization or locks.

Author:

Tim Fox

Method Summary

Modifier and Type	Method and Description
void	clear() Clear all entries in the map
void	close() Close and release the map
V	get(K key) Get a value from the map
boolean	isEmpty()
Set<K>	keySet()
V	put(K key, V value) Put an entry in the map
V	putIfAbsent(K key, V value) Put the entry only if there is no existing entry for that key
V	remove(K key) Remove an entry from the map
boolean	removeIfPresent(K key, V value) Remove the entry only if there is an entry with the specified key and value
V	replace(K key, V value) Replace the entry only if there is an existing entry with the key
boolean	replaceIfPresent(K key, V oldValue, V newValue) Replace the entry only if there is an existing entry with the specified key and value
int	size() Get the size of the map
Collection<V>	values()

Method Detail

get

V get(K key)

Get a value from the map

Parameters:

key - the key

Returns:

the value, or null if none

put

V put(K key,
      V value)

Put an entry in the map

Parameters:

key - the key

value - the value

Returns:

return the old value, or null if none

remove

V remove(K key)

Remove an entry from the map

Parameters:

key - the key

Returns:

the old value

clear

void clear()

Clear all entries in the map

size

int size()

Get the size of the map

Returns:

the number of entries in the map

isEmpty

boolean isEmpty()

Returns:

true if there are zero entries in the map

putIfAbsent

V putIfAbsent(K key,
              V value)

Put the entry only if there is no existing entry for that key

Parameters:

key - the key

value - the value

Returns:

the old value or null, if none

removeIfPresent

boolean removeIfPresent(K key,
                        V value)

Remove the entry only if there is an entry with the specified key and value

Parameters:

key - the key

value - the value

Returns:

true if removed

replaceIfPresent

boolean replaceIfPresent(K key,
                         V oldValue,
                         V newValue)

Replace the entry only if there is an existing entry with the specified key and value

Parameters:

key - the key

oldValue - the old value

newValue - the new value

Returns:

true if removed

replace

V replace(K key,
          V value)

Replace the entry only if there is an existing entry with the key

Parameters:

key - the key

value - the new value

Returns:

the old value

close

void close()

Close and release the map

keySet

Set<K> keySet()

Returns:

the set of keys in the map

values

Collection<V> values()

Returns:

the set of values in the map