> ## Documentation Index
> Fetch the complete documentation index at: https://docs.quickblox.com/llms.txt
> Use this file to discover all available pages before exploring further.
# User Presence
> Learn how to track user presence updates and check user status using ping.
## Before you begin
1. Register a [QuickBlox account](https://admin.quickblox.com/signin). This is a matter of a few minutes and you will be able to use this account to build your apps.
2. Configure QuickBlox SDK for your app. Check out [Setup](/sdks/android-setup) page for more details.
3. Create a user session to be able to use QuickBlox functionality. See [Authentication](/sdks/android-authentication) page to learn how to do it.
4. Connect to the Chat server. See [Connection](/sdks/android-chat-connection) page to learn how to do it.
Visit [Key Concepts](/docs/key-concepts) page to learn the most important QuickBlox concepts.
## Subscribe to contact presence updates
You can listen to the contact presence updates in real-time using the `QBRosterListener`. However, you can listen to the presence of only those users who have been added to the contact list. See [this section](/sdks/android-chat-contact-list) to learn how to implement the Contact List.
```Java theme={null}
// you should do this after login (connect) to the Chat
final QBRoster contactsRoster = QBChatService.getInstance().getRoster();
QBRosterListener rosterListener = new QBRosterListener() {
@Override
public void entriesDeleted(Collection userIds) {
}
@Override
public void entriesAdded(Collection userIds) {
}
@Override
public void entriesUpdated(Collection userIds) {
}
@Override
public void presenceChanged(QBPresence presence) {
if (presence == null) {
// no user in your contact list
return;
}
// if a user uses several devices, you need to do additional check for presence
QBPresence qbPresence = contactsRoster.getPresence(presence.getUserId());
if (qbPresence.getType() == QBPresence.Type.online) {
// user is online
} else {
// user is offline
}
}
};
contactsRoster.setSubscriptionMode(QBRoster.SubscriptionMode.mutual);
contactsRoster.addRosterListener(rosterListener);
```
```Kotlin theme={null}
// you should do this after login (connect) to the Chat
val contactsRoster = QBChatService.getInstance().roster
val rosterListener: QBRosterListener = object : QBRosterListener {
override fun entriesDeleted(userIds: Collection) {
}
override fun entriesAdded(userIds: Collection) {
}
override fun entriesUpdated(userIds: Collection) {
}
override fun presenceChanged(presence: QBPresence) {
if (presence == null) {
// no user in your contact list
return
}
// if a user uses several devices, you need to do additional check for presence
val qbPresence = contactsRoster.getPresence(presence.userId)
if (qbPresence.type == QBPresence.Type.online) {
// user is online
} else {
// user is offline
}
}
}
contactsRoster.subscriptionMode = QBRoster.SubscriptionMode.mutual
contactsRoster.addRosterListener(rosterListener)
```
## Ping user
QuickBlox SDK can send application-level pings to a user. As a result, you can check if the user is connected to the Chat server.
```Java theme={null}
QBPingManager pingManager = QBChatService.getInstance().getPingManager();
Integer userId = 6453;
pingManager.pingUser(userId, new QBEntityCallback() {
@Override
public void onSuccess(Void aVoid, Bundle bundle) {
}
@Override
public void onError(QBResponseException exception) {
}
});
```
```Kotlin theme={null}
val pingManager = QBChatService.getInstance().pingManager
val userId = 6453
pingManager.pingUser(userId, object : QBEntityCallback {
override fun onSuccess(aVoid: Void, bundle: Bundle) {
}
override fun onError(exception: QBResponseException) {
}
})
```
| Argument | Required | Description |
| -------- | -------- | --------------- |
| userID | yes | ID of the user. |
## Ping server
QuickBlox SDK can send application-level pings to a server. As a result, you can check if there is a connection with the Chat server.
```Java theme={null}
QBPingManager pingManager = QBChatService.getInstance().getPingManager();
pingManager.pingServer(new QBEntityCallback() {
@Override
public void onSuccess(Void aVoid, Bundle bundle) {
}
@Override
public void onError(QBResponseException exception) {
}
});
```
```Kotlin theme={null}
val pingManager = QBChatService.getInstance().pingManager
pingManager.pingServer(object : QBEntityCallback {
override fun onSuccess(aVoid: Void, bundle: Bundle) {
}
override fun onError(exception: QBResponseException) {
}
})
```
## Add ping listener
Your pings can be unsuccessful. To handle unsuccessful pings, use the `PingFailedListener`. It enables your app to listen to failed ping attempts.
```Java theme={null}
QBPingManager pingManager = QBChatService.getInstance().getPingManager();
PingFailedListener pingFailedListener = new PingFailedListener() {
@Override
public void pingFailed() {
}
};
// add PingManager when you need it
pingManager.addPingFailedListener(pingFailedListener);
// remove PingManager when you no longer need it
pingManager.removePingFailedListener(pingFailedListener);
```
```Kotlin theme={null}
val pingManager = QBChatService.getInstance().pingManager
val pingFailedListener = PingFailedListener {
}
// Add PingManager when you need it
pingManager.addPingFailedListener(pingFailedListener)
// Remove PingManager when you no longer need it
pingManager.removePingFailedListener(pingFailedListener)
```