For AI agents: this page in Markdown: https://www.pubnub.com/docs/sdks/java/api-reference/presence.md. Documentation index: https://www.pubnub.com/llms-full.txt.

Presence API for Java SDK

Breaking changes in v9.0.0

PubNub Java SDK version 9.0.0 unifies the codebases for Java and Kotlin SDKs, introduces a new way of instantiating the PubNub client, and changes asynchronous API callbacks and emitted status events. These changes can impact applications built with previous versions (< 9.0.0) of the Java SDK.

For more details about what has changed, refer to Java/Kotlin SDK migration guide.

Presence lets you track who is online or offline and store custom state information. Presence shows:

  • When a user has joined or left a channel
  • How many users are subscribed to a particular channel (occupancy)
  • Which channels a user or device is subscribed to
  • Presence state associated with these users

Learn more about our Presence feature in the Presence overview.

Here now​

Requires Presence

This method requires that the Presence add-on is enabled for your key in the Admin Portal.

For information on how to receive presence events and what those events are, refer to Presence Events.

This method returns information about the current state of a channel, including a list of unique user IDs (universally unique identifiers, UUIDs) currently subscribed to the channel and the total occupancy count of the channel.

Cache

This method has a 3-second response cache time.

Method(s)​

To call Here Now you can use the following method(s) in the Java SDK:

1this.pubnub.hereNow()
2    .channels(Array)
3    .channelGroups(Arrays)
4    .includeState(true)
5    .includeUUIDs(true)
6    .limit(int)
7    .offset(Integer)
required
channels#
Type: Array
Default: no default
The channels to get the here now details.
channelGroups#
Type: Arrays
Default: no default
The channelGroups to get the here now details. Wildcards are not supported.
includeState#
Type: Boolean
Default: false
If true, the response will include the presence states of the users for channels/channelGroups
includeUUIDs#
Type: Boolean
Default: true
If true, the response will include the UUIDs of the connected clients.
limit#
Type: int
Default: 1000
Maximum number of occupants to return per channel. Valid range: 0-1000. The server enforces the maximum of 1000 and rejects values outside this range. Use 0 to get occupancy counts without user details (when limit=0, the server omits UUIDs entirely).
offset#
Type: Integer
Default: null
Zero-based starting index for pagination. Returns occupants starting from this position in the list. Must be >= 0. Requires limit > 0. Server rejects negative values. Use with limit to paginate through large occupant lists.
async required#
Type: Consumer<Result>
Default: no default
Consumer of a Result of type PNHereNowResult

Sample code​

Get a list of UUIDs subscribed to channel​

1

Returns​

The hereNow() operation returns a PNHereNowResult which contains the following operations:

getTotalChannels()#
Type: Int
Total Channels.
getTotalOccupancy()#
Type: Int
Total Occupancy.
getChannels()#
Type: Map<String, PNHereNowChannelData>
A map with values of PNHereNowChannelData for each channel. See PNHereNowChannelData for more details.

PNHereNowChannelData​

getChannelName()#
Type: String
Channel name.
getOccupancy()#
Type: Int
Occupancy of the channel.
getOccupants()#
Type: List<PNHereNowOccupantData>
A list of PNHereNowOccupantData, see PNHereNowOccupantData for more details.

PNHereNowOccupantData​

getUuid()#
Type: String
UUIDs of the user.
getState()#
Type: Object
State of the user.

Other examples​

Returning state​

Requires Presence

This method requires that the Presence add-on is enabled for your key in the Admin Portal.

For information on how to receive presence events and what those events are, refer to Presence Events.

1

Return occupancy only​

Requires Presence

This method requires that the Presence add-on is enabled for your key in the Admin Portal.

For information on how to receive presence events and what those events are, refer to Presence Events.

You can return only the occupancy information for a single channel by specifying the channel and setting UUIDs to false:

1

Here now for channel groups​

1

Where now​

Requires Presence

This method requires that the Presence add-on is enabled for your key in the Admin Portal.

For information on how to receive presence events and what those events are, refer to Presence Events.

This method returns the list of channels a UUID is subscribed to.

Timeout events

If the app restarts (or the page refreshes) within the heartbeat window, no timeout event is generated.

Method(s)​

To call whereNow() you can use the following method(s) in the Java SDK:

1pubnub.whereNow()
2    .uuid(String)
required
uuid#
Type: String
Uuid of the user we want to spy on.
async required#
Type: Command
Execute as async.

Sample code​

You simply need to define the uuid and the callback function to be used to send the data to as in the example below.

Get a list of channels a UUID is subscribed to​

1

Returns​

The whereNow() operation returns a PNWhereNowResult which contains the following operations:

getChannels()#
Type: List<String>
The list of channels where the UUID is present.

Other examples​

Obtain information about the current list of channels of some other UUID​

1

User state​

Requires Presence

This method requires that the Presence add-on is enabled for your key in the Admin Portal.

For information on how to receive presence events and what those events are, refer to Presence Events.

Clients can set a dynamic custom state (score, game state, location) for their users on one or more channels and store it on a channel as long as the user stays subscribed.

The state is not persisted, and when the client disconnects, the state data is lost. For more information, refer to Presence State.

Presence state format

Presence state must be expressed as a JsonObject. When calling setState, be sure to supply an initialized JsonObject or POJO which can be serialized to a JsonObject.

Method(s)​

Set state​

1this.pubnub.setPresenceState()
2    .channels(Array)
3    .channelGroups(Array)
4    .state(HashMap)
5    .uuid(String)
required
channels#
Type: Array
Channels to set state.
channelGroups#
Type: Array
ChannelGroups to set state.
state#
Type: HashMap
State to set.
uuid#
Type: String
Set state for specific UUID.
async required#
Type: Consumer<Result>
Consumer of a Result of type PNSetStateResult.

Get state​

1this.pubnub.getPresenceState()
2    .channels(Arrays)
3    .channelGroups(Arrays)
4    .uuid(String)
required
channels#
Type: Arrays
Channel name to fetch the state.
channelGroups#
Type: Arrays
ChannelGroups name to fetch the state.
uuid#
Type: String
UUID
async required#
Type: Consumer<Result>
Consumer of a Result of type PNGetStateResult.

Sample code​

Set state​

1

Get state​

1

Returns​

The setPresenceState() operation returns a PNSetStateResult which contains the following operations:

getState()#
Type: Map<String, Object>
Map of UUIDs and the user states.

The getPresenceState() operation returns a PNGetStateResult which contains the following operations:

getStateByUUID()#
Type: Map<String, Object>
Map of UUIDs and the user states.

Other examples​

Set state for channels in channel group​

1

The above code would return the following response to the client:

1

Was this page useful?

Last updated on