Redis or Valkey based distributed [Map](https://static.javadoc.io/org.redisson/redisson/latest/org/redisson/api/RMap.html) object for Java implements [ConcurrentMap](https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/ConcurrentMap.html) interface. This object is thread-safe. Consider to use [Live Object service](services.md/#live-object-service) to store POJO object as Redis or Valkey Map. Redis or Valkey uses serialized state to check key uniqueness instead of key's `hashCode()`/`equals()` methods.
If Map used mostly for read operations and/or network roundtrips are undesirable use Map with [Local cache](#eviction-local-cache-and-data-partitioning) support.
RMap object allows to bind a [Lock](locks-and-synchronizers.md/#lock)/[ReadWriteLock](locks-and-synchronizers.md/#readwritelock)/[Semaphore](locks-and-synchronizers.md/#semaphore)/[CountDownLatch](locks-and-synchronizers.md/#countdownlatch) object per key:
Redisson provides various Map structure implementations with multiple important features:
**local cache** - so called `near cache` used to speed up read operations and avoid network roundtrips. It caches Map entries on Redisson side and executes read operations up to **45x faster** in comparison with common implementation. Local cache instances with the same name connected to the same pub/sub channel. This channel is used for exchanging of update/invalidate events between all instances. Local cache store doesn't use `hashCode()`/`equals()` methods of key object, instead it uses hash of serialized state. It's recommended to use each local cached instance as a singleton per unique name since it has own state for local cache.
**data partitioning** - although any Map object is cluster compatible its content isn't scaled/partitioned across multiple master nodes in cluster. Data partitioning allows to scale available memory, read/write operations and entry eviction process for individual Map instance in cluster.
**1. No eviction**
Each object implements [RMap](https://static.javadoc.io/org.redisson/redisson/latest/org/redisson/api/RMap.html), [Async](https://static.javadoc.io/org.redisson/redisson/latest/org/redisson/api/RMapAsync.html), [Reactive](https://static.javadoc.io/org.redisson/redisson/latest/org/redisson/api/RMapReactive.html) and [RxJava3](https://static.javadoc.io/org.redisson/redisson/latest/org/redisson/api/RMapRx.html) interfaces.
Available implementations:
|RedissonClient<br/>method name | Local<br/>cache | Data<br/>partitioning | Ultra-fast<br/>read/write |
|getClusteredMap()<br/><sub><i>available only in [Redisson PRO](https://redisson.pro)</i></sub> | ❌ | ✔️ | ✔️ |
|getClusteredLocalCachedMap()<br/><sub><i>available only in [Redisson PRO](https://redisson.pro)</i></sub> | ✔️ | ✔️ | ✔️ |
<br/>
**2. Scripted eviction**
Allows to define `time to live` or `max idle time` parameters per map entry. Eviction is done on Redisson side through a custom scheduled task which removes expired entries using Lua script. Eviction task is started once per unique object name at the moment of getting Map instance. If instance isn't used and has expired entries it should be get again to start the eviction process. This leads to extra Redis or Valkey calls and eviction task per unique map object name.
Entries are cleaned time to time by `org.redisson.eviction.EvictionScheduler`. By default, it removes 100 expired entries at a time. This can be changed through [cleanUpKeysAmount](../configuration.md) setting. Task launch time tuned automatically and depends on expired entries amount deleted in previous time and varies between 5 second to 30 minutes by default. This time interval can be changed through [minCleanUpDelay](../configuration.md) and [maxCleanUpDelay](../configuration.md). For example, if clean task deletes 100 entries each time it will be executed every 5 seconds (minimum execution delay). But if current expired entries amount is lower than previous one then execution delay will be increased by 1.5 times and decreased otherwise.
Each object implements [RMapCache](https://static.javadoc.io/org.redisson/redisson/latest/org/redisson/api/RMapCache.html), [Async](https://static.javadoc.io/org.redisson/redisson/latest/org/redisson/api/RMapCacheAsync.html), [Reactive](https://static.javadoc.io/org.redisson/redisson/latest/org/redisson/api/RMapCacheReactive.html) and [RxJava3](https://static.javadoc.io/org.redisson/redisson/latest/org/redisson/api/RMapCacheRx.html) interfaces.
Available implementations:
|RedissonClient<br/>method name | Local<br/>cache | Data<br/>partitioning | Ultra-fast<br/>read/write |
|getLocalCachedMapCache()<br/><sub><i>available only in [Redisson PRO](https://redisson.pro)</i></sub> | ✔️ | ❌ | ✔️ |
|getClusteredMapCache()<br/><sub><i>available only in [Redisson PRO](https://redisson.pro)</i></sub> | ❌ | ✔️ | ✔️ |
|getClusteredLocalCachedMapCache()<br/><sub><i>available only in [Redisson PRO](https://redisson.pro)</i></sub> | ✔️ | ✔️ | ✔️ |
<br/>
**3. Advanced eviction**
Allows to define `time to live` parameter per map entry. Doesn't use an entry eviction task, entries are cleaned on Redis or Valkey side.
Each object implements [RMapCacheV2](https://static.javadoc.io/org.redisson/redisson/latest/org/redisson/api/RMapCacheV2.html), [Async](https://static.javadoc.io/org.redisson/redisson/latest/org/redisson/api/RMapCacheV2Async.html), [Reactive](https://static.javadoc.io/org.redisson/redisson/latest/org/redisson/api/RMapCacheV2Reactive.html) and [RxJava3](https://static.javadoc.io/org.redisson/redisson/latest/org/redisson/api/RMapCacheV2Rx.html) interfaces.
Available implementations:
|RedissonClient<br/>method name | Local<br/>cache | Data<br/>partitioning | Ultra-fast<br/>read/write |
|getMapCacheV2()<br/><sub><i>available only in [Redisson PRO](https://redisson.pro)</i></sub> | ❌ | ✔️ | ✔️ |
|getLocalCachedMapCacheV2()<br/><sub><i>available only in [Redisson PRO](https://redisson.pro)</i></sub> | ✔️ | ✔️ | ✔️ |
<br/>
**4. Native eviction**
Allows to define `time to live` parameter per map entry. Doesn't use an entry eviction task, entries are cleaned on Redis side. Requires **Redis 7.4+**.
Each object implements [RMapCacheNative](https://static.javadoc.io/org.redisson/redisson/latest/org/redisson/api/RMapCacheNative.html), [Async](https://static.javadoc.io/org.redisson/redisson/latest/org/redisson/api/RMapCacheNativeAsync.html), [Reactive](https://static.javadoc.io/org.redisson/redisson/latest/org/redisson/api/RMapCacheNativeReactive.html) and [RxJava3](https://static.javadoc.io/org.redisson/redisson/latest/org/redisson/api/RMapCacheNativeRx.html) interfaces.
Available implementations:
|RedissonClient<br/>method name | Local<br/>cache | Data<br/>partitioning | Ultra-fast<br/>read/write |
map.put("key1", new SomeObject(), 10, TimeUnit.MINUTES);
// ttl = 10 minutes, maxIdleTime = 10 seconds
map.put("key1", new SomeObject(), 10, TimeUnit.MINUTES, 10, TimeUnit.SECONDS);
// ttl = 3 seconds
map.putIfAbsent("key2", new SomeObject(), 3, TimeUnit.SECONDS);
// ttl = 40 seconds, maxIdleTime = 10 seconds
map.putIfAbsent("key2", new SomeObject(), 40, TimeUnit.SECONDS, 10, TimeUnit.SECONDS);
// if object is not used anymore
map.destroy();
```
**Local cache**
Map object with local cache support implements [RLocalCachedMap](https://static.javadoc.io/org.redisson/redisson/latest/org/redisson/api/RLocalCachedMap.html) which extends [ConcurrentMap](https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/ConcurrentMap.html) interface. This object is thread-safe.
It's recommended to use single instance of `LocalCachedMap` instance per name for each Redisson client instance. Same `LocalCachedMapOptions` object should be used across all instances with the same name.
Follow options can be supplied during object creation:
Map object with data partitioning support implements `org.redisson.api.RClusteredMap` which extends `java.util.concurrent.ConcurrentMap` interface. Read more details about data partitioning [here](data-partitioning.md).
SomeObject prevObject = map.put("123", new SomeObject());
SomeObject currentObject = map.putIfAbsent("323", new SomeObject());
SomeObject obj = map.remove("123");
map.fastPut("321", new SomeObject());
map.fastRemove("321");
```
### Persistence
Redisson allows to store Map data in external storage along with Redis or Valkey store.
Use cases:
1. Redisson Map object as a cache between an application and external storage.
2. Increase durability of Redisson Map data and life-span of evicted entries.
3. Caching for databases, web services or any other data source.
**Read-through strategy**
If requested entry doesn't exist in the Redisson Map object
when it will be loaded using provided [MapLoader](https://static.javadoc.io/org.redisson/redisson/latest/org/redisson/api/map/MapLoader.html) object. Code example:
```java
MapLoader<String,String> mapLoader = new MapLoader<String,String>() {
@Override
public Iterable<String> loadAllKeys() {
List<String> list = new ArrayList<String>();
Statement statement = conn.createStatement();
try {
ResultSet result = statement.executeQuery("SELECT id FROM student");
while (result.next()) {
list.add(result.getString(1));
}
} finally {
statement.close();
}
return list;
}
@Override
public String load(String key) {
PreparedStatement preparedStatement = conn.prepareStatement("SELECT name FROM student where id = ?");
try {
preparedStatement.setString(1, key);
ResultSet result = preparedStatement.executeQuery();
When the Map entry is being updated method won't return until
Redisson update it in an external storage using [MapWriter](https://static.javadoc.io/org.redisson/redisson/latest/org/redisson/api/map/MapWriter.html) object. Code example:
```java
MapWriter<String,String> mapWriter = new MapWriter<String,String>() {
Updates of Map object are accumulated in batches and asynchronously written with defined delay to external storage through [MapWriter](https://static.javadoc.io/org.redisson/redisson/latest/org/redisson/api/map/MapWriter.html) object.
`writeBehindDelay` - delay of batched write or delete operation. Default value is 1000 milliseconds.
`writeBehindBatchSize` - size of batch. Each batch contains Map Entry write or delete commands. Default value is 50.
This feature available for `RMap`, `RMapCache`, `RLocalCachedMap` and `RLocalCachedMapCache` objects.
Usage of `RLocalCachedMap` and `RLocalCachedMapCache` objects boost Redis or Valkey read-operations up to **45x times** and give almost instant speed for database, web service or any other data source.
int listenerId = map.addListener(new EntryUpdatedListener<Integer,Integer>() {
@Override
public void onUpdated(EntryEvent<Integer,Integer> event) {
event.getKey(); // key
event.getValue() // new value
event.getOldValue() // old value
// ...
}
});
int listenerId = map.addListener(new EntryCreatedListener<Integer,Integer>() {
@Override
public void onCreated(EntryEvent<Integer,Integer> event) {
event.getKey(); // key
event.getValue() // value
// ...
}
});
int listenerId = map.addListener(new EntryExpiredListener<Integer,Integer>() {
@Override
public void onExpired(EntryEvent<Integer,Integer> event) {
event.getKey(); // key
event.getValue() // value
// ...
}
});
int listenerId = map.addListener(new EntryRemovedListener<Integer,Integer>() {
@Override
public void onRemoved(EntryEvent<Integer,Integer> event) {
event.getKey(); // key
event.getValue() // value
// ...
}
});
map.removeListener(listenerId);
```
### LRU/LFU bounded Map
Map object which implements `RMapCache` interface could be bounded using [Least Recently Used (LRU)](https://en.wikipedia.org/wiki/Cache_replacement_policies#LRU) or [Least Frequently Used (LFU)](https://en.wikipedia.org/wiki/Least_frequently_used) order. Bounded Map allows to store map entries within defined limit and retire entries in defined order.
// tries to set limit map to 10 entries using LRU eviction algorithm
map.trySetMaxSize(10);
// ... using LFU eviction algorithm
map.trySetMaxSize(10, EvictionMode.LFU);
// set or change limit map to 10 entries using LRU eviction algorithm
map.setMaxSize(10);
// ... using LFU eviction algorithm
map.setMaxSize(10, EvictionMode.LFU);
map.put("1", "2");
map.put("3", "3", 1, TimeUnit.SECONDS);
```
## Multimap
Redis or Valkey based [Multimap](https://static.javadoc.io/org.redisson/redisson/latest/org/redisson/api/RMultimap.html) for Java allows to bind multiple values per key. This object is thread-safe. Keys amount limited to `4 294 967 295` elements. Redis or Valkey uses serialized state to check key uniqueness instead of key's `hashCode()`/`equals()` methods.
It has [Async](https://static.javadoc.io/org.redisson/redisson/latest/org/redisson/api/RMultimapAsync.html), [Reactive](https://static.javadoc.io/org.redisson/redisson/latest/org/redisson/api/RMultimapReactive.html) and [RxJava3](https://static.javadoc.io/org.redisson/redisson/latest/org/redisson/api/RMultimapRx.html) interfaces.
### Set based Multimap
Set based Multimap doesn't allow duplications for values per key.
List based [Multimap](https://static.javadoc.io/org.redisson/redisson/latest/org/redisson/api/RMultimap.html) object for Java stores entries in insertion order and allows duplicates for values mapped to key.
Multimap distributed object for Java with eviction support implemented by separated MultimapCache object. There are [RSetMultimapCache](https://static.javadoc.io/org.redisson/redisson/latest/org/redisson/api/RSetMultimapCache.html) and [RListMultimapCache](https://static.javadoc.io/org.redisson/redisson/latest/org/redisson/api/RListMultimapCache.html) objects for Set and List based Multimaps respectively.
Eviction task is started once per unique object name at the moment of getting Multimap instance. If instance isn't used and has expired entries it should be get again to start the eviction process. This leads to extra Redis or Valkey calls and eviction task per unique map object name.
Entries are cleaned time to time by `org.redisson.eviction.EvictionScheduler`. By default, it removes 100 expired entries at a time. This can be changed through [cleanUpKeysAmount](../configuration.md) setting. Task launch time tuned automatically and depends on expired entries amount deleted in previous time and varies between 5 second to 30 minutes by default. This time interval can be changed through [minCleanUpDelay](../configuration.md) and [maxCleanUpDelay](../configuration.md). For example, if clean task deletes 100 entries each time it will be executed every 5 seconds (minimum execution delay). But if current expired entries amount is lower than previous one then execution delay will be increased by 1.5 times and decreased otherwise.
Redisson allows binding listeners per `RSetMultimap` or `RListMultimap` object. This requires the `notify-keyspace-events` setting to be enabled on Redis or Valkey side.
`RSetMultimap` listeners:
|Listener class name|Event description | Valkey or Redis<br/>`notify-keyspace-events` value|
[RJsonStore](https://www.javadoc.io/doc/org.redisson/redisson/latest/org/redisson/api/RJsonStore.html) is a distributed Key Value store for JSON objects. Compatible with Redis or Valkey. This object is thread-safe. Allows to store JSON value mapped by key. Operations can be executed per key or group of keys. Value is stored/retrieved using `JSON.*` commands. Both key and value are POJO objects.
RJsonStore<String,MyObject> store = redisson.getJsonStore("test", StringCodec.INSTANCE, new JacksonCodec(MyObject.class));
MyObject t1 = new MyObject();
t1.setName("name1");
MyObject t2 = new MyObject();
t2.setName("name2");
Map<String,MyObject> entries = new HashMap<>();
entries.put("1", t1);
entries.put("2", t2);
store.set(entries);
// search
SearchResult r = s.search("idx", "*", QueryOptions.defaults()
.returnAttributes(new ReturnAttribute("name")));
// aggregation
AggregationResult ar = s.aggregate("idx", "*", AggregationOptions.defaults()
.withCursor().load("name"));
```
### Local Cache
Redisson provides [JSON Store](#json-store) implementation with local cache.
**local cache** - so called near cache used to speed up read operations and avoid network roundtrips. It caches JSON Store entries on Redisson side and executes read operations up to **45x faster** in comparison with regular implementation. Local cached instances with the same name are connected to the same pub/sub channel. This channel is used for exchanging of update/invalidate events between all instances. Local cache store doesn't use `hashCode()`/`equals()` methods of key object, instead it uses hash of serialized state. It's recommended to use each local cached instance as a singleton per unique name since it has own state for local cache.
It's recommended to use a single instance of `RLocalCachedJsonStore` instance per name for each Redisson client instance. Same `LocalCachedJsonStoreOptions` object should be used across all instances with the same name.
Follow options can be supplied during object creation:
RLocalCachedJsonStore<String,MyObject> store = redisson.getLocalCachedJsonStore(ops);
// multiple entries at once
long deleted = store.delete(Set.of("1", "2"));
// or delete entry per call
boolean status = store.delete("1");
boolean status = store.delete("2");
```
## Set
Redis or Valkey based [Set](https://static.javadoc.io/org.redisson/redisson/latest/org/redisson/api/RSet.html) object for Java implements [Set](https://docs.oracle.com/javase/8/docs/api/java/util/Set.html) interface. This object is thread-safe. Keeps elements uniqueness via element state comparison. Set size limited to `4 294 967 295` elements. Redis or Valkey uses serialized state to check value uniqueness instead of value's `hashCode()`/`equals()` methods.
It has [Async](https://static.javadoc.io/org.redisson/redisson/latest/org/redisson/api/RSetAsync.html), [Reactive](https://static.javadoc.io/org.redisson/redisson/latest/org/redisson/api/RSetReactive.html) and [RxJava3](https://static.javadoc.io/org.redisson/redisson/latest/org/redisson/api/RSetRx.html) interfaces.
```java
RSet<SomeObject> set = redisson.getSet("anySet");
set.add(new SomeObject());
set.remove(new SomeObject());
```
RSet object allows to bind a [Lock](locks-and-synchronizers.md/#lock)/[ReadWriteLock](locks-and-synchronizers.md/#readwritelock)/[Semaphore](locks-and-synchronizers.md/#semaphore)/[CountDownLatch](locks-and-synchronizers.md/#countdownlatch) object per value:
```
RSet<MyObject> set = redisson.getSet("anySet");
MyObject value = new MyObject();
RLock lock = map.getLock(value);
lock.lock();
try {
// process value ...
} finally {
lock.unlock();
}
```
### Eviction and data partitioning
Redisson provides various Set structure implementations with a few important features:
**data partitioning** - although any Set object is cluster compatible its content isn't scaled/partitioned across multiple master nodes in cluster. Data partitioning allows to scale available memory, read/write operations and entry eviction process for individual Set instance in cluster.
**entry eviction** - allows to define `time to live` parameter per SetCache entry. Redis or Valkey set structure doesn't support eviction thus it's done on Redisson side through a custom scheduled task which removes expired entries using Lua script. Eviction task is started once per unique object name at the moment of getting SetCache instance. If instance isn't used and has expired entries it should be get again to start the eviction process. This leads to extra Redis or Valkey calls and eviction task per unique SetCache object name.
Entries are cleaned time to time by `org.redisson.eviction.EvictionScheduler`. By default, it removes 100 expired entries at a time. This can be changed through [cleanUpKeysAmount](../configuration.md) setting. Task launch time tuned automatically and depends on expired entries amount deleted in previous time and varies between 5 second to 30 minutes by default. This time interval can be changed through [minCleanUpDelay](../configuration.md) and [maxCleanUpDelay](../configuration.md). For example, if clean task deletes 100 entries each time it will be executed every 5 seconds (minimum execution delay). But if current expired entries amount is lower than previous one then execution delay will be increased by 1.5 times and decreased otherwise.
**advanced entry eviction** - improved version of the **entry eviction** process. Doesn't use an entry eviction task.
**Eviction**
Set object with eviction support implements [RSetCache](https://static.javadoc.io/org.redisson/redisson/latest/org/redisson/api/RSetCache.html), [Async](https://static.javadoc.io/org.redisson/redisson/latest/org/redisson/api/RSetCacheAsync.html), [Reactive](https://static.javadoc.io/org.redisson/redisson/latest/org/redisson/api/RSetCacheReactive.html) and [RxJava3](https://static.javadoc.io/org.redisson/redisson/latest/org/redisson/api/RSetCacheRx.html) interfaces.
Code example:
```java
RSetCache<SomeObject> set = redisson.getSetCache("mySet");
// or
RMapCache<SomeObject> set = redisson.getClusteredSetCache("mySet");
// ttl = 10 minutes,
set.add(new SomeObject(), 10, TimeUnit.MINUTES);
// if object is not used anymore
map.destroy();
```
**Data partitioning**
Map object with data partitioning support implements `org.redisson.api.RClusteredSet`. Read more details about data partitioning [here](data-partitioning.md).
Code example:
```java
RClusteredSet<SomeObject> set = redisson.getClusteredSet("mySet");
// or
RClusteredSet<SomeObject> set = redisson.getClusteredSetCache("mySet");
// ttl = 10 minutes,
map.add(new SomeObject(), 10, TimeUnit.MINUTES);
```
Below is the list of all available Set implementations:
int listenerId = set.addListener(new DeletedObjectListener() {
@Override
public void onDeleted(String name) {
// ...
}
});
// ...
set.removeListener(listenerId);
```
## SortedSet
Redis or Valkey based distributed [SortedSet](https://static.javadoc.io/org.redisson/redisson/latest/org/redisson/api/RSortedSet.html) for Java implements [SortedSet](https://docs.oracle.com/javase/8/docs/api/java/util/SortedSet.html) interface. This object is thread-safe. It uses comparator to sort elements and keep uniqueness. For String data type it's recommended to use [LexSortedSet](#lexsortedset) object due to performance gain.
```java
RSortedSet<Integer> set = redisson.getSortedSet("anySet");
set.trySetComparator(new MyComparator()); // set object comparator
set.add(3);
set.add(1);
set.add(2);
set.removeAsync(0);
set.addAsync(5);
```
## ScoredSortedSet
Redis or Valkey based distributed [ScoredSortedSet](https://static.javadoc.io/org.redisson/redisson/latest/org/redisson/api/RScoredSortedSet.html) object. Sorts elements by score defined during element insertion. Keeps elements uniqueness via element state comparison.
It has [Async](https://static.javadoc.io/org.redisson/redisson/latest/org/redisson/api/RScoredSortedSetAsync.html), [Reactive](https://static.javadoc.io/org.redisson/redisson/latest/org/redisson/api/RScoredSortedSetReactive.html) and [RxJava3](https://static.javadoc.io/org.redisson/redisson/latest/org/redisson/api/RScoredSortedSetRx.html) interfaces. Set size is limited to `4 294 967 295` elements.
```java
RScoredSortedSet<SomeObject> set = redisson.getScoredSortedSet("simple");
set.add(0.13, new SomeObject(a, b));
set.addAsync(0.251, new SomeObject(c, d));
set.add(0.302, new SomeObject(g, d));
set.pollFirst();
set.pollLast();
int index = set.rank(new SomeObject(g, d)); // get element index
Double score = set.getScore(new SomeObject(g, d)); // get element score
```
### Data partitioning
Although 'RScoredSortedSet' object is cluster compatible its content isn't scaled across multiple master nodes. `RScoredSortedSet` data partitioning available only in cluster mode and implemented by separate `RClusteredScoredSortedSet` object. Size is limited by whole Cluster memory. More about partitioning [here](data-partitioning.md).
Below is the list of all available `RScoredSortedSet` implementations:
|RedissonClient <br/> method name | Data partitioning <br/> support | Ultra-fast read/write |
Redisson allows binding listeners per `RScoredSortedSet` object. This requires the `notify-keyspace-events` setting to be enabled on Redis or Valkey side.
RScoredSortedSet<String> set = redisson.getScoredSortedSet("anySet");
int listenerId = set.addListener(new DeletedObjectListener() {
@Override
public void onDeleted(String name) {
// ...
}
});
// ...
set.removeListener(listenerId);
```
## LexSortedSet
Redis or Valkey based distributed [Set](https://static.javadoc.io/org.redisson/redisson/latest/org/redisson/api/RLexSortedSet.html) object for Java allows String objects only and implements `java.util.Set<String>` interface. It keeps elements in lexicographical order and maintain elements uniqueness via element state comparison.
It has [Async](https://static.javadoc.io/org.redisson/redisson/latest/org/redisson/api/RLexSortedSetAsync.html), [Reactive](https://static.javadoc.io/org.redisson/redisson/latest/org/redisson/api/RLexSortedSetReactive.html) and [RxJava3](https://static.javadoc.io/org.redisson/redisson/latest/org/redisson/api/RLexSortedSetRx.html) interfaces.
```java
RLexSortedSet set = redisson.getLexSortedSet("simple");
Redisson allows binding listeners per `RLexSortedSet` object. This requires the `notify-keyspace-events` setting to be enabled on Redis or Valkey side.
RLexSortedSet<String> set = redisson.getLexSortedSet("anySet");
int listenerId = set.addListener(new DeletedObjectListener() {
@Override
public void onDeleted(String name) {
// ...
}
});
// ...
set.removeListener(listenerId);
```
## List
Redis or Valkey based distributed [List](https://static.javadoc.io/org.redisson/redisson/latest/org/redisson/api/RList.html) object for Java implements `java.util.List` interface. It keeps elements in insertion order.
It has [Async](https://static.javadoc.io/org.redisson/redisson/latest/org/redisson/api/RListAsync.html), [Reactive](https://static.javadoc.io/org.redisson/redisson/latest/org/redisson/api/RListReactive.html) and [RxJava3](https://static.javadoc.io/org.redisson/redisson/latest/org/redisson/api/RListRx.html) interfaces. List size is limited to `4 294 967 295` elements.
```java
RList<SomeObject> list = redisson.getList("anyList");
int listenerId = list.addListener(new DeletedObjectListener() {
@Override
public void onDeleted(String name) {
// ...
}
});
// ...
list.removeListener(listenerId);
```
## Queue
Redis or Valkey based distributed unbounded [Queue](https://static.javadoc.io/org.redisson/redisson/latest/org/redisson/api/RQueue.html) object for Java implements [java.util.Queue](https://docs.oracle.com/javase/8/docs/api/java/util/Queue.html) interface. This object is thread-safe.
It has [Async](https://static.javadoc.io/org.redisson/redisson/latest/org/redisson/api/RQueueAsync.html), [Reactive](https://static.javadoc.io/org.redisson/redisson/latest/org/redisson/api/RQueueReactive.html) and [RxJava3](https://static.javadoc.io/org.redisson/redisson/latest/org/redisson/api/RQueueRx.html) interfaces.
int listenerId = queue.addListener(new DeletedObjectListener() {
@Override
public void onDeleted(String name) {
// ...
}
});
// ...
queue.removeListener(listenerId);
```
## Deque
Redis or Valkey based distributed unbounded [Deque](https://static.javadoc.io/org.redisson/redisson/latest/org/redisson/api/RDeque.html) object for Java implements `java.util.Deque` interface. This object is thread-safe.
It has [Async](https://static.javadoc.io/org.redisson/redisson/latest/org/redisson/api/RDequeAsync.html), [Reactive](https://static.javadoc.io/org.redisson/redisson/latest/org/redisson/api/RDequeReactive.html) and [RxJava3](https://static.javadoc.io/org.redisson/redisson/latest/org/redisson/api/RDequeRx.html) interfaces.
int listenerId = deque.addListener(new DeletedObjectListener() {
@Override
public void onDeleted(String name) {
// ...
}
});
// ...
deque.removeListener(listenerId);
```
## Blocking Queue
Redis or Valkey based distributed unbounded [BlockingQueue](https://static.javadoc.io/org.redisson/redisson/latest/org/redisson/api/RBlockingQueue.html) object for Java implements `java.util.concurrent.BlockingQueue` interface. This object is thread-safe.
It has [Async](https://static.javadoc.io/org.redisson/redisson/latest/org/redisson/api/RBlockingQueueAsync.html), [Reactive](https://static.javadoc.io/org.redisson/redisson/latest/org/redisson/api/RBlockingQueueReactive.html) and [RxJava3](https://static.javadoc.io/org.redisson/redisson/latest/org/redisson/api/RBlockingQueueRx.html) interfaces.
`poll`, `pollFromAny`, `pollLastAndOfferFirstTo` and `take` methods are resubscribed automatically during re-connection to server or failover.
## Bounded Blocking Queue
Redis or Valkey based distributed [BoundedBlockingQueue](https://static.javadoc.io/org.redisson/redisson/latest/org/redisson/api/RBoundedBlockingQueue.html) for Java implements `java.util.concurrent.BlockingQueue` interface. BoundedBlockingQueue size limited to `4 294 967 295` elements. This object is thread-safe.
Queue capacity should be defined once by `trySetCapacity()` method before the usage:
// returns `true` if capacity set successfully and `false` if it already set.
queue.trySetCapacity(2);
queue.offer(new SomeObject(1));
queue.offer(new SomeObject(2));
// will be blocked until free space available in queue
queue.put(new SomeObject());
SomeObject obj = queue.peek();
SomeObject someObj = queue.poll();
SomeObject ob = queue.poll(10, TimeUnit.MINUTES);
```
`poll`, `pollFromAny`, `pollLastAndOfferFirstTo` and `take` methods will be resubscribed automatically during reconnection to server or failover.
## Blocking Deque
Java implementation of Redis or Valkey based [BlockingDeque](https://static.javadoc.io/org.redisson/redisson/latest/org/redisson/api/RBlockingDeque.html) implements `java.util.concurrent.BlockingDeque` interface. This object is thread-safe.
It has [Async](https://static.javadoc.io/org.redisson/redisson/latest/org/redisson/api/RBlockingDequeAsync.html), [Reactive](https://static.javadoc.io/org.redisson/redisson/latest/org/redisson/api/RBlockingDequeReactive.html) and [RxJava3](https://static.javadoc.io/org.redisson/redisson/latest/org/redisson/api/RBlockingDequeRx.html) interfaces.
`poll`, `pollFromAny`, `pollLastAndOfferFirstTo` and `take` methods are resubscribed automatically during re-connection to server or failover.
## Delayed Queue
Redis or Valkey based [DelayedQueue](https://static.javadoc.io/org.redisson/redisson/latest/org/redisson/api/RDelayedQueue.html) object for Java allows to transfer each element to destination queue with specified delay. Destination queue could be any queue implemented `RQueue` interface. This object is thread-safe.
Could be useful for exponential backoff strategy used for message delivery to consumer. If application is restarted, an instance of delayed queue should created in order for the pending items to be added to the destination queue.
Object should be destroyed if it not used anymore, but it's not necessary to call destroy method if Redisson goes shutdown.
```java
RDelayedQueue<String> delayedQueue = ...
delayedQueue.destroy();
```
## Priority Queue
Java implementation of Redis or Valkey based [PriorityQueue](https://static.javadoc.io/org.redisson/redisson/latest/org/redisson/api/RPriorityQueue.html) implements [java.util.Queue](https://docs.oracle.com/javase/8/docs/api/java/util/Queue.html) interface. Elements are ordered according to natural order of [Comparable](https://docs.oracle.com/javase/8/docs/api/java/lang/Comparable.html) interface or defined [Comparator](https://docs.oracle.com/javase/8/docs/api/java/util/Comparator.html). This object is thread-safe.
Use `trySetComparator()` method to define own [Comparator](https://docs.oracle.com/javase/8/docs/api/java/util/Comparator.html).
Code example:
```java
public class Entry implements Comparable<Entry>, Serializable {
Java implementation of Redis or Valkey based [PriorityDeque](https://static.javadoc.io/org.redisson/redisson/latest/org/redisson/api/RPriorityDeque.html) implements [java.util.Deque](https://docs.oracle.com/javase/8/docs/api/java/util/Deque.html) interface. Elements are ordered according to natural order of [java.lang.Comparable](https://docs.oracle.com/javase/8/docs/api/java/lang/Comparable.html) interface or defined [java.util.Comparator](https://docs.oracle.com/javase/8/docs/api/java/util/Comparator.html). This object is thread-safe.
Use `trySetComparator()` method to define own [Comparator](https://docs.oracle.com/javase/8/docs/api/java/util/Comparator.html).
Code example:
```java
public class Entry implements Comparable<Entry>, Serializable {
Java implementation of Redis or Valkey based [PriorityBlockingQueue](https://static.javadoc.io/org.redisson/redisson/latest/org/redisson/api/RPriorityBlockingQueue.html) similar to JDK [java.util.concurrent.PriorityBlockingQueue](https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/PriorityBlockingQueue.html) object. Elements are ordered according to natural order of [java.lang.Comparable](https://docs.oracle.com/javase/8/docs/api/java/lang/Comparable.html) interface or defined [java.util.Comparator](https://docs.oracle.com/javase/8/docs/api/java/util/Comparator.html). This object is thread-safe.
Use `trySetComparator()` method to define own [java.util.Comparator](https://docs.oracle.com/javase/8/docs/api/java/util/Comparator.html).
`poll`, `pollLastAndOfferFirstTo` and `take` methods are resubscribed automatically during re-connection to a server or failover.
Code example:
```java
public class Entry implements Comparable<Entry>, Serializable {
Java implementation of Redis or Valkey based [PriorityBlockingDeque](https://static.javadoc.io/org.redisson/redisson/latest/org/redisson/api/RPriorityBlockingDeque.html) implements [java.util.concurrent.BlockingDeque](https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/BlockingDeque.html) interface. Elements are ordered according to natural order of [java.lang.Comparable](https://docs.oracle.com/javase/8/docs/api/java/lang/Comparable.html) interface or defined [java.util.Comparator](https://docs.oracle.com/javase/8/docs/api/java/util/Comparator.html). This object is thread-safe.
Use `trySetComparator()` method to define own [java.util.Comparator](https://docs.oracle.com/javase/8/docs/api/java/util/Comparator.html).
`poll`, `pollLastAndOfferFirstTo`, `take` methods are resubscribed automatically during re-connection to Redis or Valkey server or failover.
Code example:
```java
public class Entry implements Comparable<Entry>, Serializable {
Java implementation of Redis or Valkey based [Stream](https://static.javadoc.io/org.redisson/redisson/latest/org/redisson/api/RStream.html) object wraps [Stream](https://redis.io/topics/streams-intro) feature. Basically it allows to create Consumers Group which consume data added by Producers. This object is thread-safe.
int listenerId = stream.addListener(new DeletedObjectListener() {
@Override
public void onDeleted(String name) {
// ...
}
});
int listenerId = stream.addListener(new StreamAddListener() {
@Override
public void onAdd(String name) {
// ...
}
});
// ...
stream.removeListener(listenerId);
```
## Ring Buffer
Java implementation of Redis or Valkey based [RingBuffer](https://www.javadoc.io/doc/org.redisson/redisson/latest/org/redisson/api/RRingBuffer.html) implements [java.util.Queue](https://docs.oracle.com/javase/8/docs/api/java/util/Queue.html) interface. This structure evicts elements from the head if queue capacity became full. This object is thread-safe.
Should be initialized with capacity size by `trySetCapacity()` method before usage.
int listenerId = queue.addListener(new DeletedObjectListener() {
@Override
public void onDeleted(String name) {
// ...
}
});
// ...
queue.removeListener(listenerId);
```
## Transfer Queue
Java implementation of Redis or Valkey based [TransferQueue](https://www.javadoc.io/doc/org.redisson/redisson/latest/org/redisson/api/RTransferQueue.html) implements [java.util.concurrent.TransferQueue](https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/TransferQueue.html) interface. Provides set of `transfer` methods which return only when value was successfully hand off to consumer. This object is thread-safe.
`poll` and `take` methods are resubscribed automatically during re-connection to a server or failover.
Java implementation of Redis or Valkey based [TimeSeries](https://www.javadoc.io/doc/org.redisson/redisson/latest/org/redisson/api/RTimeSeries.html) object allows to store value by timestamp and define TTL(time-to-live) per entry. Values are ordered by timestamp. This object is thread-safe.
