Join Session - CometChat Docs

Join a call session using one of two approaches: the quick start method with a session ID, or the advanced flow with manual token generation for more control.

Overview

The CometChat Calls SDK provides two ways to join a session:

Approach	Best For	Complexity
Join with Session ID	Most use cases - simple and straightforward	Low - One method call
Join with Token	Custom token management, pre-generation, caching	Medium - Two-step process

Both approaches require a container view in your layout and properly configured SessionSettings.

Container Setup

Add a container view to your layout where the call interface will be rendered:

<RelativeLayout
    android:id="@+id/call_view_container"
    android:layout_width="match_parent"
    android:layout_height="match_parent" />

The call UI will be dynamically added to this container when you join the session.

Join with Session ID

The simplest way to join a session. Pass a session ID and the SDK automatically generates the token and joins the call.

Kotlin
Java

val sessionId = "SESSION_ID"
val callViewContainer = findViewById<RelativeLayout>(R.id.call_view_container)

val sessionSettings = CometChatCalls.SessionSettingsBuilder()
    .setDisplayName("John Doe")
    .setType(SessionType.VIDEO)
    .build()

CometChatCalls.joinSession(sessionId, sessionSettings, callViewContainer, 
    object : CometChatCalls.CallbackListener<CallSession>() {
        override fun onSuccess(callSession: CallSession) {
            Log.d(TAG, "Joined session successfully")
        }

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

String sessionId = "SESSION_ID";
RelativeLayout callViewContainer = findViewById(R.id.call_view_container);

SessionSettings sessionSettings = new CometChatCalls.SessionSettingsBuilder()
    .setDisplayName("John Doe")
    .setType(SessionType.VIDEO)
    .build();

CometChatCalls.joinSession(sessionId, sessionSettings, callViewContainer, 
    new CometChatCalls.CallbackListener<CallSession>() {
        @Override
        public void onSuccess(CallSession callSession) {
            Log.d(TAG, "Joined session successfully");
        }

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

Parameter	Type	Description
`sessionId`	String	Unique identifier for the call session
`sessionSettings`	SessionSettings	Configuration for the session
`callViewContainer`	RelativeLayout	Container view for the call UI
`listener`	CallbackListener	Callback for success/error handling

All participants joining the same call must use the same session ID.

Join with Token

For scenarios requiring more control over token generation, such as pre-generating tokens, implementing custom caching strategies, or managing token lifecycle separately. Step 1: Generate Token Generate a call token for the session. Each token is unique to a specific session and user combination.

Kotlin
Java

val sessionId = "SESSION_ID"

CometChatCalls.generateToken(sessionId, object : CometChatCalls.CallbackListener<GenerateToken>() {
    override fun onSuccess(token: GenerateToken) {
        Log.d(TAG, "Token generated: ${token.token}")
        // Store or use the token
    }

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

String sessionId = "SESSION_ID";

CometChatCalls.generateToken(sessionId, new CometChatCalls.CallbackListener<GenerateToken>() {
    @Override
    public void onSuccess(GenerateToken token) {
        Log.d(TAG, "Token generated: " + token.getToken());
        // Store or use the token
    }

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

Parameter	Type	Description
`sessionId`	String	Unique identifier for the call session
`listener`	CallbackListener	Callback returning the generated token

Step 2: Join with Token Use the generated token to join the session. This gives you control over when and how the token is used.

Kotlin
Java

val callViewContainer = findViewById<RelativeLayout>(R.id.call_view_container)

val sessionSettings = CometChatCalls.SessionSettingsBuilder()
    .setDisplayName("John Doe")
    .setType(SessionType.VIDEO)
    .build()

// Use the previously generated token
CometChatCalls.joinSession(generatedToken, sessionSettings, callViewContainer, 
    object : CometChatCalls.CallbackListener<CallSession>() {
        override fun onSuccess(callSession: CallSession) {
            Log.d(TAG, "Joined session successfully")
        }

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

RelativeLayout callViewContainer = findViewById(R.id.call_view_container);

SessionSettings sessionSettings = new CometChatCalls.SessionSettingsBuilder()
    .setDisplayName("John Doe")
    .setType(SessionType.VIDEO)
    .build();

// Use the previously generated token
CometChatCalls.joinSession(generatedToken, sessionSettings, callViewContainer, 
    new CometChatCalls.CallbackListener<CallSession>() {
        @Override
        public void onSuccess(CallSession callSession) {
            Log.d(TAG, "Joined session successfully");
        }

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

Parameter	Type	Description
`callToken`	GenerateToken	Previously generated token object
`sessionSettings`	SessionSettings	Configuration for the session
`callViewContainer`	RelativeLayout	Container view for the call UI
`listener`	CallbackListener	Callback for success/error handling

Complete Example

Kotlin
Java

val sessionId = "SESSION_ID"
val callViewContainer = findViewById<RelativeLayout>(R.id.call_view_container)

// Step 1: Generate token
CometChatCalls.generateToken(sessionId, object : CometChatCalls.CallbackListener<GenerateToken>() {
    override fun onSuccess(token: GenerateToken) {
        // Step 2: Join with token
        val sessionSettings = CometChatCalls.SessionSettingsBuilder()
            .setDisplayName("John Doe")
            .setType(SessionType.VIDEO)
            .build()

        CometChatCalls.joinSession(token, sessionSettings, callViewContainer, 
            object : CometChatCalls.CallbackListener<CallSession>() {
                override fun onSuccess(callSession: CallSession) {
                    Log.d(TAG, "Joined session successfully")
                }

                override fun onError(e: CometChatException) {
                    Log.e(TAG, "Failed to join: ${e.message}")
                }
            }
        )
    }

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

String sessionId = "SESSION_ID";
RelativeLayout callViewContainer = findViewById(R.id.call_view_container);

// Step 1: Generate token
CometChatCalls.generateToken(sessionId, new CometChatCalls.CallbackListener<GenerateToken>() {
    @Override
    public void onSuccess(GenerateToken token) {
        // Step 2: Join with token
        SessionSettings sessionSettings = new CometChatCalls.SessionSettingsBuilder()
            .setDisplayName("John Doe")
            .setType(SessionType.VIDEO)
            .build();

        CometChatCalls.joinSession(token, sessionSettings, callViewContainer, 
            new CometChatCalls.CallbackListener<CallSession>() {
                @Override
                public void onSuccess(CallSession callSession) {
                    Log.d(TAG, "Joined session successfully");
                }

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

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

Error Handling

Common errors when joining a session:

Error Code	Description
`ERROR_COMETCHAT_CALLS_SDK_INIT`	SDK not initialized - call `init()` first
`ERROR_AUTH_TOKEN`	User not logged in or auth token invalid
`ERROR_CALL_SESSION_ID`	Session ID is null or empty
`ERROR_CALL_TOKEN`	Invalid or missing call token
`ERROR_CALLING_VIEW_REF_NULL`	Container view is null
`ERROR_JSON_EXCEPTION`	Invalid session settings or response parsing error

​Overview

​Container Setup

​Join with Session ID

​Join with Token

​Error Handling

Overview

Container Setup

Join with Session ID

Join with Token

Error Handling