IMPORTANT: In July 2025, we stopped releasing new versions of KTX modules, and we removed the KTX libraries from the Firebase Android BoM (v34.0.0). If you use KTX APIs from the previously released KTX modules, we recommend that you migrate your app to use KTX APIs from the main modules instead. For details, see the FAQ about this initiative.

Chat

class Chat

Representation of a multi-turn interaction with a model.

Captures and stores the history of communication in memory, and provides it as context with each new message.

Note: This object is not thread-safe, and calling sendMessage multiple times without waiting for a response will throw an InvalidStateException.

Summary

Public constructors
`Chat(model: GenerativeModel, history: MutableList<Content>)`

Public functions
`suspend GenerateContentResponse`	`sendMessage(prompt: Bitmap)` Sends a message using the existing history of this chat as context and the provided image prompt.
`suspend GenerateContentResponse`	`sendMessage(prompt: Content)` Sends a message using the provided `prompt`; automatically providing the existing `history` as context.
`suspend GenerateContentResponse`	`sendMessage(prompt: String)` Sends a message using the provided `text prompt`; automatically providing the existing `history` as context.
`Flow<GenerateContentResponse>`	`sendMessageStream(prompt: Bitmap)` Sends a message using the existing history of this chat as context and the provided image prompt.
`Flow<GenerateContentResponse>`	`sendMessageStream(prompt: Content)` Sends a message using the existing history of this chat as context and the provided `Content` prompt.
`Flow<GenerateContentResponse>`	`sendMessageStream(prompt: String)` Sends a message using the existing history of this chat as context and the provided text prompt.

Public properties
`MutableList<Content>`	`history` The previous content from the chat that has been successfully sent and received from the model.

Public constructors

Chat

Chat(model: GenerativeModel, history: MutableList<Content> = ArrayList())

Parameters
`model: GenerativeModel`	The model to use for the interaction.

Public functions

sendMessage

suspend fun sendMessage(prompt: Bitmap): GenerateContentResponse

Sends a message using the existing history of this chat as context and the provided image prompt.

If successful, the message and response will be added to the history. If unsuccessful, history will remain unchanged.

Parameters
`prompt: Bitmap`	The input that, together with the history, will be given to the model as the prompt.

Throws
`com.google.firebase.vertexai.type.InvalidStateException: com.google.firebase.vertexai.type.InvalidStateException`	if `prompt` is not coming from the 'user' role.
`com.google.firebase.vertexai.type.InvalidStateException: com.google.firebase.vertexai.type.InvalidStateException`	if the `Chat` instance has an active request.

sendMessage

suspend fun sendMessage(prompt: Content): GenerateContentResponse

Sends a message using the provided prompt; automatically providing the existing history as context.

If successful, the message and response will be added to the history. If unsuccessful, history will remain unchanged.

Parameters
`prompt: Content`	The input that, together with the history, will be given to the model as the prompt.

Throws
`com.google.firebase.vertexai.type.InvalidStateException: com.google.firebase.vertexai.type.InvalidStateException`	if `prompt` is not coming from the 'user' role.
`com.google.firebase.vertexai.type.InvalidStateException: com.google.firebase.vertexai.type.InvalidStateException`	if the `Chat` instance has an active request.

sendMessage

suspend fun sendMessage(prompt: String): GenerateContentResponse

Sends a message using the provided text prompt; automatically providing the existing history as context.

If successful, the message and response will be added to the history. If unsuccessful, history will remain unchanged.

Parameters
`prompt: String`	The input that, together with the history, will be given to the model as the prompt.

Throws
`com.google.firebase.vertexai.type.InvalidStateException: com.google.firebase.vertexai.type.InvalidStateException`	if `prompt` is not coming from the 'user' role.
`com.google.firebase.vertexai.type.InvalidStateException: com.google.firebase.vertexai.type.InvalidStateException`	if the `Chat` instance has an active request.

sendMessageStream

fun sendMessageStream(prompt: Bitmap): Flow<GenerateContentResponse>

Sends a message using the existing history of this chat as context and the provided image prompt.

The response from the model is returned as a stream.

If successful, the message and response will be added to the history. If unsuccessful, history will remain unchanged.

Parameters
`prompt: Bitmap`	The input that, together with the history, will be given to the model as the prompt.

Throws
`com.google.firebase.vertexai.type.InvalidStateException: com.google.firebase.vertexai.type.InvalidStateException`	if `prompt` is not coming from the 'user' role.
`com.google.firebase.vertexai.type.InvalidStateException: com.google.firebase.vertexai.type.InvalidStateException`	if the `Chat` instance has an active request.

sendMessageStream

fun sendMessageStream(prompt: Content): Flow<GenerateContentResponse>

Sends a message using the existing history of this chat as context and the provided Content prompt.

The response from the model is returned as a stream.

If successful, the message and response will be added to the history. If unsuccessful, history will remain unchanged.

Parameters
`prompt: Content`	The input that, together with the history, will be given to the model as the prompt.

Throws
`com.google.firebase.vertexai.type.InvalidStateException: com.google.firebase.vertexai.type.InvalidStateException`	if `prompt` is not coming from the 'user' role.
`com.google.firebase.vertexai.type.InvalidStateException: com.google.firebase.vertexai.type.InvalidStateException`	if the `Chat` instance has an active request.

sendMessageStream

fun sendMessageStream(prompt: String): Flow<GenerateContentResponse>

Sends a message using the existing history of this chat as context and the provided text prompt.

The response from the model is returned as a stream.

If successful, the message and response will be added to the history. If unsuccessful, history will remain unchanged.

Parameters
`prompt: String`	The input(s) that, together with the history, will be given to the model as the prompt.

Throws
`com.google.firebase.vertexai.type.InvalidStateException: com.google.firebase.vertexai.type.InvalidStateException`	if `prompt` is not coming from the 'user' role.
`com.google.firebase.vertexai.type.InvalidStateException: com.google.firebase.vertexai.type.InvalidStateException`	if the `Chat` instance has an active request.

Public properties

history

val history: MutableList<Content>

The previous content from the chat that has been successfully sent and received from the model. This will be provided to the model for each message sent (as context for the discussion).