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

Parameter	Description
channels Type: Array Default: n/a	The channels to get the here now details.
channelGroups Type: Arrays Default: n/a	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 * Type: Consumer<Result> Default: n/a	Consumer of a Result of type PNHereNowResult

Sample code

Reference code

This example is a self-contained code snippet ready to be run. It includes necessary imports and executes methods with console logging. Use it as a reference when working with other examples in this document.

Get a list of UUIDs subscribed to channel

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Returns

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

Method	Description
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

Method	Description
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

Method	Description
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.

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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:

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Here now for channel groups

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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

Parameter	Description
uuid Type: String	Uuid of the user we want to spy on.
async * 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

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Returns

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

Method	Description
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

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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

Parameter	Description
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 * 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

Parameter	Description
channels Type: Arrays	Channel name to fetch the state.
channelGroups Type: Arrays	ChannelGroups name to fetch the state.
uuid Type: String	UUID
async * Type: Consumer<Result>	Consumer of a Result of type PNGetStateResult.

Sample code

Set state

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Get state

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Returns

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

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

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

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

Other examples

Set state for channels in channel group

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

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