Authentication

Before users can make or receive calls, they must be authenticated with the CometChat Calls SDK. This guide covers the login and logout methods.

Sample UsersCometChat provides 5 test users: cometchat-uid-1, cometchat-uid-2, cometchat-uid-3, cometchat-uid-4, and cometchat-uid-5.

Use getLoggedInUser() to find out whether — and which — user has a persisted session, for example at app launch to decide whether to show your login screen. It returns a CallUser object if a user is logged in, or null if no session exists. You never need it as a guard before login(): calling login() is always safe — if the same user is already logged in it returns the existing session without a network round trip, and if a different user is logged in the SDK switches to the new user automatically (see Switching Users).

Check who is logged in, not just whetherOn a shared or reused device, the persisted session may belong to a different user. If your app skips its own login flow because getLoggedInUser() is non-null, compare the returned UID against your app’s current account first — otherwise calls are silently placed as the previous user.

Kotlin
Java

val myAppsCurrentUserUid = "cometchat-uid-1" // your app's signed-in user ID
val loggedInUser = CometChatCalls.getLoggedInUser()

if (loggedInUser != null && loggedInUser.uid.equals(myAppsCurrentUserUid, ignoreCase = true)) {
    // The right user's session is already active — skip your login flow
    Log.d(TAG, "Session restored for: ${loggedInUser.uid}")
} else {
    // No session, or the session belongs to someone else — run login()
}

String myAppsCurrentUserUid = "cometchat-uid-1"; // your app's signed-in user ID
CallUser loggedInUser = CometChatCalls.getLoggedInUser();

if (loggedInUser != null && loggedInUser.getUid().equalsIgnoreCase(myAppsCurrentUserUid)) {
    // The right user's session is already active — skip your login flow
    Log.d(TAG, "Session restored for: " + loggedInUser.getUid());
} else {
    // No session, or the session belongs to someone else — run login()
}

This method is suitable for development and testing. For production apps, use Auth Token login instead.

Security NoticeUsing the API Key directly in client code is not recommended for production. Use Auth Token authentication for enhanced security.

Kotlin
Java

val uid = "cometchat-uid-1" // Replace with your user's UID
val apiKey = "API_KEY" // Replace with your API Key

CometChatCalls.login(uid, apiKey, object : CometChatCalls.CallbackListener<CallUser>() {
    override fun onSuccess(user: CallUser) {
        Log.d(TAG, "Login successful: ${user.uid}")
    }

    override fun onError(e: CometChatException) {
        Log.e(TAG, "Login failed: ${e.message}")
    }
})

String uid = "cometchat-uid-1"; // Replace with your user's UID
String apiKey = "API_KEY"; // Replace with your API Key

CometChatCalls.login(uid, apiKey, new CometChatCalls.CallbackListener<CallUser>() {
    @Override
    public void onSuccess(CallUser user) {
        Log.d(TAG, "Login successful: " + user.getUid());
    }

    @Override
    public void onError(CometChatException e) {
        Log.e(TAG, "Login failed: " + e.getMessage());
    }
});

Parameter	Type	Description
`uid`	String	The unique identifier of the user to login
`apiKey`	String	Your CometChat API Key
`listener`	CallbackListener	Callback for success/error handling

This is the recommended authentication method for production applications. The Auth Token is generated server-side, keeping your API Key secure.

Auth Token Flow

User authenticates with your backend
Your backend calls the CometChat Create Auth Token API
Your backend returns the Auth Token to the client
Client uses the Auth Token to login

Kotlin
Java

val authToken = "AUTH_TOKEN" // Token received from your backend

CometChatCalls.login(authToken, object : CometChatCalls.CallbackListener<CallUser>() {
    override fun onSuccess(user: CallUser) {
        Log.d(TAG, "Login successful: ${user.uid}")
    }

    override fun onError(e: CometChatException) {
        Log.e(TAG, "Login failed: ${e.message}")
    }
})

String authToken = "AUTH_TOKEN"; // Token received from your backend

CometChatCalls.login(authToken, new CometChatCalls.CallbackListener<CallUser>() {
    @Override
    public void onSuccess(CallUser user) {
        Log.d(TAG, "Login successful: " + user.getUid());
    }

    @Override
    public void onError(CometChatException e) {
        Log.e(TAG, "Login failed: " + e.getMessage());
    }
});

Parameter	Type	Description
`authToken`	String	Auth Token generated via CometChat API
`listener`	CallbackListener	Callback for success/error handling

Switching Users

On a shared or reused device, call login() with the new user’s credentials — there is no need to check or clear the previous session yourself. If a different user is logged in, the SDK logs them out automatically before logging the new user in. Calling login() for the user who is already logged in simply returns the existing session.

Kotlin
Java

// Logs out the previous user (if any) and logs the new user in
CometChatCalls.login(newUserUid, apiKey, object : CometChatCalls.CallbackListener<CallUser>() {
    override fun onSuccess(user: CallUser) {
        Log.d(TAG, "Switched to user: ${user.uid}")
    }

    override fun onError(e: CometChatException) {
        Log.e(TAG, "User switch failed: ${e.message}")
    }
})

// Logs out the previous user (if any) and logs the new user in
CometChatCalls.login(newUserUid, apiKey, new CometChatCalls.CallbackListener<CallUser>() {
    @Override
    public void onSuccess(CallUser user) {
        Log.d(TAG, "Switched to user: " + user.getUid());
    }

    @Override
    public void onError(CometChatException e) {
        Log.e(TAG, "User switch failed: " + e.getMessage());
    }
});

CallUser Object

On successful login, the callback returns a CallUser object containing user information:

Property	Type	Description
`uid`	String	Unique identifier of the user
`name`	String	Display name of the user
`avatar`	String	URL of the user’s avatar image
`status`	String	User’s online status

Logout

Call logout() when the user signs out of your application. This clears the local session and disconnects from CometChat services; the SDK stays initialized, so the next user can login() directly.

Kotlin
Java

CometChatCalls.logout(object : CometChatCalls.CallbackListener<String>() {
    override fun onSuccess(message: String) {
        Log.d(TAG, "Logout successful")
    }

    override fun onError(e: CometChatException) {
        Log.e(TAG, "Logout failed: ${e.message}")
    }
})

CometChatCalls.logout(new CometChatCalls.CallbackListener<String>() {
    @Override
    public void onSuccess(String message) {
        Log.d(TAG, "Logout successful");
    }

    @Override
    public void onError(CometChatException e) {
        Log.e(TAG, "Logout failed: " + e.getMessage());
    }
});

Error Handling

Common authentication errors:

Error Code	Description
`ERROR_INVALID_UID`	The provided UID is empty or invalid
`ERROR_UID_WITH_SPACE`	The UID contains spaces (not allowed)
`ERROR_API_KEY_NOT_FOUND`	The API Key is missing or invalid
`ERROR_BLANK_AUTHTOKEN`	The Auth Token is empty
`ERROR_LOGIN_IN_PROGRESS`	A login operation is already in progress

Overview

Getting Started

Call Session

Features

Advanced

Migration Guide

Resources

Auth Token Flow

Switching Users

CallUser Object

Logout

Error Handling

​Check Login Status

​Login with UID and API Key

​Login with Auth Token

​Auth Token Flow

​Switching Users

​CallUser Object

​Logout

​Error Handling

Check Login Status

Login with UID and API Key

Login with Auth Token

Auth Token Flow

Switching Users

CallUser Object

Logout

Error Handling