Using the Gemini API
, you can build freeform conversations across
multiple turns. The Firebase AI Logic
SDK simplifies the process by managing
the state of the conversation, so unlike with generateContent()
(or generateContentStream()
), you don't have to store the conversation history
yourself.
Jump to code for text-only chat Jump to code for iterative image editing Jump to code for streamed responses
Before you begin
Click your Gemini API provider to view provider-specific content and code on this page.
If you haven't already, complete the getting started guide
, which describes how to
set up your Firebase project, connect your app to Firebase, add the SDK,
initialize the backend service for your chosen Gemini API
provider, and
create a GenerativeModel
instance.
For testing and iterating on your prompts, we recommend using Google AI Studio .
Build a text-only chat experience
Before trying this sample, complete the Before you begin
section of this guide
to set up your project and app.
In that section, you'll also click a button for your chosen Gemini API provider so that you see provider-specific content on this page.
In that section, you'll also click a button for your chosen Gemini API provider so that you see provider-specific content on this page.
To build a multi-turn conversation (like chat), start off by initializing the
chat by calling startChat()
. Then use sendMessage()
to send a new user message, which
will also append the message and the response to the chat history.
There are two possible options for role
associated with the content in a
conversation:
-
user: the role which provides the prompts. This value is the default for calls tosendMessage(), and the function throws an exception if a different role is passed. -
model: the role which provides the responses. This role can be used when callingstartChat()with existinghistory.
Swift
You can call startChat()
and sendMessage()
to send a new user message:
import
FirebaseAILogic
// Initialize the Gemini Developer API backend service
let
ai
=
FirebaseAI
.
firebaseAI
(
backend
:
.
googleAI
())
// Create a `GenerativeModel` instance with a model that supports your use case
let
model
=
ai
.
generativeModel
(
modelName
:
"gemini-2.5-flash"
)
// Optionally specify existing chat history
let
history
=
[
ModelContent
(
role
:
"user"
,
parts
:
"Hello, I have 2 dogs in my house."
),
ModelContent
(
role
:
"model"
,
parts
:
"Great to meet you. What would you like to know?"
),
]
// Initialize the chat with optional chat history
let
chat
=
model
.
startChat
(
history
:
history
)
// To generate text output, call sendMessage and pass in the message
let
response
=
try
await
chat
.
sendMessage
(
"How many paws are in my house?"
)
print
(
response
.
text
??
"No text in response."
)
Kotlin
You can call startChat()
and sendMessage()
to send a new user message:
// Initialize the Gemini Developer API backend service
// Create a `GenerativeModel` instance with a model that supports your use case
val
model
=
Firebase
.
ai
(
backend
=
GenerativeBackend
.
googleAI
())
.
generativeModel
(
"gemini-2.5-flash"
)
// Initialize the chat
val
chat
=
model
.
startChat
(
history
=
listOf
(
content
(
role
=
"user"
)
{
text
(
"Hello, I have 2 dogs in my house."
)
},
content
(
role
=
"model"
)
{
text
(
"Great to meet you. What would you like to know?"
)
}
)
)
val
response
=
chat
.
sendMessage
(
"How many paws are in my house?"
)
print
(
response
.
text
)
Java
You can call startChat()
and sendMessage()
to send a new user message:
ListenableFuture
.
// Initialize the Gemini Developer API backend service
// Create a `GenerativeModel` instance with a model that supports your use case
GenerativeModel
ai
=
FirebaseAI
.
getInstance
(
GenerativeBackend
.
googleAI
())
.
generativeModel
(
"gemini-2.5-flash"
);
// Use the GenerativeModelFutures Java compatibility layer which offers
// support for ListenableFuture and Publisher APIs
GenerativeModelFutures
model
=
GenerativeModelFutures
.
from
(
ai
);
// (optional) Create previous chat history for context
Content
.
Builder
userContentBuilder
=
new
Content
.
Builder
();
userContentBuilder
.
setRole
(
"user"
);
userContentBuilder
.
addText
(
"Hello, I have 2 dogs in my house."
);
Content
userContent
=
userContentBuilder
.
build
();
Content
.
Builder
modelContentBuilder
=
new
Content
.
Builder
();
modelContentBuilder
.
setRole
(
"model"
);
modelContentBuilder
.
addText
(
"Great to meet you. What would you like to know?"
);
Content
modelContent
=
userContentBuilder
.
build
();
List<Content>
history
=
Arrays
.
asList
(
userContent
,
modelContent
);
// Initialize the chat
ChatFutures
chat
=
model
.
startChat
(
history
);
// Create a new user message
Content
.
Builder
messageBuilder
=
new
Content
.
Builder
();
messageBuilder
.
setRole
(
"user"
);
messageBuilder
.
addText
(
"How many paws are in my house?"
);
Content
message
=
messageBuilder
.
build
();
// Send the message
ListenableFuture<GenerateContentResponse>
response
=
chat
.
sendMessage
(
message
);
Futures
.
addCallback
(
response
,
new
FutureCallback<GenerateContentResponse>
()
{
@Override
public
void
onSuccess
(
GenerateContentResponse
result
)
{
String
resultText
=
result
.
getText
();
System
.
out
.
println
(
resultText
);
}
@Override
public
void
onFailure
(
Throwable
t
)
{
t
.
printStackTrace
();
}
},
executor
);
Web
You can call startChat()
and sendMessage()
to send a new user message:
import
{
initializeApp
}
from
"firebase/app"
;
import
{
getAI
,
getGenerativeModel
,
GoogleAIBackend
}
from
"firebase/ai"
;
// TODO(developer) Replace the following with your app's Firebase configuration
// See: https://firebase.google.com/docs/web/learn-more#config-object
const
firebaseConfig
=
{
// ...
};
// Initialize FirebaseApp
const
firebaseApp
=
initializeApp
(
firebaseConfig
);
// Initialize the Gemini Developer API backend service
const
ai
=
getAI
(
firebaseApp
,
{
backend
:
new
GoogleAIBackend
()
});
// Create a `GenerativeModel` instance with a model that supports your use case
const
model
=
getGenerativeModel
(
ai
,
{
model
:
"gemini-2.5-flash"
});
async
function
run
()
{
const
chat
=
model
.
startChat
({
history
:
[
{
role
:
"user"
,
parts
:
[{
text
:
"Hello, I have 2 dogs in my house."
}],
},
{
role
:
"model"
,
parts
:
[{
text
:
"Great to meet you. What would you like to know?"
}],
},
],
generationConfig
:
{
maxOutputTokens
:
100
,
},
});
const
msg
=
"How many paws are in my house?"
;
const
result
=
await
chat
.
sendMessage
(
msg
);
const
text
=
result
.
response
.
text
();
console
.
log
(
text
);
}
run
();
Dart
You can call startChat()
and sendMessage()
to send a new user message:
import
'package:firebase_ai/firebase_ai.dart'
;
import
'package:firebase_core/firebase_core.dart'
;
import
'firebase_options.dart'
;
// Initialize FirebaseApp
await
Firebase
.
initializeApp
(
options:
DefaultFirebaseOptions
.
currentPlatform
,
);
// Initialize the Gemini Developer API backend service
// Create a `GenerativeModel` instance with a model that supports your use case
final
model
=
FirebaseAI
.
googleAI
().
generativeModel
(
model:
'gemini-2.5-flash'
);
final
chat
=
model
.
startChat
();
// Provide a prompt that contains text
final
prompt
=
[
Content
.
text
(
'Write a story about a magic backpack.'
)];
final
response
=
await
chat
.
sendMessage
(
prompt
);
print
(
response
.
text
);
Unity
You can call StartChat()
and SendMessageAsync()
to send a new user message:
using
Firebase
;
using
Firebase.AI
;
// Initialize the Gemini Developer API backend service
var
ai
=
FirebaseAI
.
GetInstance
(
FirebaseAI
.
Backend
.
GoogleAI
());
// Create a `GenerativeModel` instance with a model that supports your use case
var
model
=
ai
.
GetGenerativeModel
(
modelName
:
"gemini-2.5-flash"
);
// Optionally specify existing chat history
var
history
=
new
[]
{
ModelContent
.
Text
(
"Hello, I have 2 dogs in my house."
),
new
ModelContent
(
"model"
,
new
ModelContent
.
TextPart
(
"Great to meet you. What would you like to know?"
)),
};
// Initialize the chat with optional chat history
var
chat
=
model
.
StartChat
(
history
);
// To generate text output, call SendMessageAsync and pass in the message
var
response
=
await
chat
.
SendMessageAsync
(
"How many paws are in my house?"
);
UnityEngine
.
Debug
.
Log
(
response
.
Text
??
"No text in response."
);
Learn how to choose a model appropriate for your use case and app.
Iterate and edit images using multi-turn chat
Before trying this sample, complete the Before you begin
section of this guide
to set up your project and app.
In that section, you'll also click a button for your chosen Gemini API provider so that you see provider-specific content on this page.
In that section, you'll also click a button for your chosen Gemini API provider so that you see provider-specific content on this page.
Using multi-turn chat, you can iterate with a Gemini model on the images that it generates or that you supply.
Make sure to create a GenerativeModel
instance, include responseModalities: ["TEXT", "IMAGE"]
startChat()
and sendMessage()
to send new user
messages.
Swift
import
FirebaseAILogic
// Initialize the Gemini Developer API backend service
// Create a `GenerativeModel` instance with a Gemini model that supports image output
let
generativeModel
=
FirebaseAI
.
firebaseAI
(
backend
:
.
googleAI
()).
generativeModel
(
modelName
:
"gemini-2.5-flash-image"
,
// Configure the model to respond with text and images (required)
generationConfig
:
GenerationConfig
(
responseModalities
:
[.
text
,
.
image
])
)
// Initialize the chat
let
chat
=
model
.
startChat
()
guard
let
image
=
UIImage
(
named
:
"scones"
)
else
{
fatalError
(
"Image file not found."
)
}
// Provide an initial text prompt instructing the model to edit the image
let
prompt
=
"Edit this image to make it look like a cartoon"
// To generate an initial response, send a user message with the image and text prompt
let
response
=
try
await
chat
.
sendMessage
(
image
,
prompt
)
// Inspect the generated image
guard
let
inlineDataPart
=
response
.
inlineDataParts
.
first
else
{
fatalError
(
"No image data in response."
)
}
guard
let
uiImage
=
UIImage
(
data
:
inlineDataPart
.
data
)
else
{
fatalError
(
"Failed to convert data to UIImage."
)
}
// Follow up requests do not need to specify the image again
let
followUpResponse
=
try
await
chat
.
sendMessage
(
"But make it old-school line drawing style"
)
// Inspect the edited image after the follow up request
guard
let
followUpInlineDataPart
=
followUpResponse
.
inlineDataParts
.
first
else
{
fatalError
(
"No image data in response."
)
}
guard
let
followUpUIImage
=
UIImage
(
data
:
followUpInlineDataPart
.
data
)
else
{
fatalError
(
"Failed to convert data to UIImage."
)
}
Kotlin
// Initialize the Gemini Developer API backend service
// Create a `GenerativeModel` instance with a Gemini model that supports image output
val
model
=
Firebase
.
ai
(
backend
=
GenerativeBackend
.
googleAI
()).
generativeModel
(
modelName
=
"gemini-2.5-flash-image"
,
// Configure the model to respond with text and images (required)
generationConfig
=
generationConfig
{
responseModalities
=
listOf
(
ResponseModality
.
TEXT
,
ResponseModality
.
IMAGE
)
}
)
// Provide an image for the model to edit
val
bitmap
=
BitmapFactory
.
decodeResource
(
context
.
resources
,
R
.
drawable
.
scones
)
// Create the initial prompt instructing the model to edit the image
val
prompt
=
content
{
image
(
bitmap
)
text
(
"Edit this image to make it look like a cartoon"
)
}
// Initialize the chat
val
chat
=
model
.
startChat
()
// To generate an initial response, send a user message with the image and text prompt
var
response
=
chat
.
sendMessage
(
prompt
)
// Inspect the returned image
var
generatedImageAsBitmap
=
response
.
candidates
.
first
().
content
.
parts
.
filterIsInstance<ImagePart>
().
firstOrNull
()
?.
image
// Follow up requests do not need to specify the image again
response
=
chat
.
sendMessage
(
"But make it old-school line drawing style"
)
generatedImageAsBitmap
=
response
.
candidates
.
first
().
content
.
parts
.
filterIsInstance<ImagePart>
().
firstOrNull
()
?.
image
Java
// Initialize the Gemini Developer API backend service
// Create a `GenerativeModel` instance with a Gemini model that supports image output
GenerativeModel
ai
=
FirebaseAI
.
getInstance
(
GenerativeBackend
.
googleAI
()).
generativeModel
(
"gemini-2.5-flash-image"
,
// Configure the model to respond with text and images (required)
new
GenerationConfig
.
Builder
()
.
setResponseModalities
(
Arrays
.
asList
(
ResponseModality
.
TEXT
,
ResponseModality
.
IMAGE
))
.
build
()
);
GenerativeModelFutures
model
=
GenerativeModelFutures
.
from
(
ai
);
// Provide an image for the model to edit
Bitmap
bitmap
=
BitmapFactory
.
decodeResource
(
resources
,
R
.
drawable
.
scones
);
// Initialize the chat
ChatFutures
chat
=
model
.
startChat
();
// Create the initial prompt instructing the model to edit the image
Content
prompt
=
new
Content
.
Builder
()
.
setRole
(
"user"
)
.
addImage
(
bitmap
)
.
addText
(
"Edit this image to make it look like a cartoon"
)
.
build
();
// To generate an initial response, send a user message with the image and text prompt
ListenableFuture<GenerateContentResponse>
response
=
chat
.
sendMessage
(
prompt
);
// Extract the image from the initial response
ListenableFuture
< @Nullable
Bitmap
>
initialRequest
=
Futures
.
transform
(
response
,
result
-
>
{
for
(
Part
part
:
result
.
getCandidates
().
get
(
0
).
getContent
().
getParts
())
{
if
(
part
instanceof
ImagePart
)
{
ImagePart
imagePart
=
(
ImagePart
)
part
;
return
imagePart
.
getImage
();
}
}
return
null
;
},
executor
);
// Follow up requests do not need to specify the image again
ListenableFuture<GenerateContentResponse>
modelResponseFuture
=
Futures
.
transformAsync
(
initialRequest
,
generatedImage
-
>
{
Content
followUpPrompt
=
new
Content
.
Builder
()
.
addText
(
"But make it old-school line drawing style"
)
.
build
();
return
chat
.
sendMessage
(
followUpPrompt
);
},
executor
);
// Add a final callback to check the reworked image
Futures
.
addCallback
(
modelResponseFuture
,
new
FutureCallback<GenerateContentResponse>
()
{
@Override
public
void
onSuccess
(
GenerateContentResponse
result
)
{
for
(
Part
part
:
result
.
getCandidates
().
get
(
0
).
getContent
().
getParts
())
{
if
(
part
instanceof
ImagePart
)
{
ImagePart
imagePart
=
(
ImagePart
)
part
;
Bitmap
generatedImageAsBitmap
=
imagePart
.
getImage
();
break
;
}
}
}
@Override
public
void
onFailure
(
Throwable
t
)
{
t
.
printStackTrace
();
}
},
executor
);
Web
import
{
initializeApp
}
from
"firebase/app"
;
import
{
getAI
,
getGenerativeModel
,
GoogleAIBackend
,
ResponseModality
}
from
"firebase/ai"
;
// TODO(developer) Replace the following with your app's Firebase configuration
// See: https://firebase.google.com/docs/web/learn-more#config-object
const
firebaseConfig
=
{
// ...
};
// Initialize FirebaseApp
const
firebaseApp
=
initializeApp
(
firebaseConfig
);
// Initialize the Gemini Developer API backend service
const
ai
=
getAI
(
firebaseApp
,
{
backend
:
new
GoogleAIBackend
()
});
// Create a `GenerativeModel` instance with a model that supports your use case
const
model
=
getGenerativeModel
(
ai
,
{
model
:
"gemini-2.5-flash-image"
,
// Configure the model to respond with text and images (required)
generationConfig
:
{
responseModalities
:
[
ResponseModality
.
TEXT
,
ResponseModality
.
IMAGE
],
},
});
// Prepare an image for the model to edit
async
function
fileToGenerativePart
(
file
)
{
const
base64EncodedDataPromise
=
new
Promise
((
resolve
)
=>
{
const
reader
=
new
FileReader
();
reader
.
onloadend
=
()
=>
resolve
(
reader
.
result
.
split
(
','
)[
1
]);
reader
.
readAsDataURL
(
file
);
});
return
{
inlineData
:
{
data
:
await
base64EncodedDataPromise
,
mimeType
:
file
.
type
},
};
}
const
fileInputEl
=
document
.
querySelector
(
"input[type=file]"
);
const
imagePart
=
await
fileToGenerativePart
(
fileInputEl
.
files
[
0
]);
// Provide an initial text prompt instructing the model to edit the image
const
prompt
=
"Edit this image to make it look like a cartoon"
;
// Initialize the chat
const
chat
=
model
.
startChat
();
// To generate an initial response, send a user message with the image and text prompt
const
result
=
await
chat
.
sendMessage
([
prompt
,
imagePart
]);
// Request and inspect the generated image
try
{
const
inlineDataParts
=
result
.
response
.
inlineDataParts
();
if
(
inlineDataParts
?
.[
0
])
{
// Inspect the generated image
const
image
=
inlineDataParts
[
0
].
inlineData
;
console
.
log
(
image
.
mimeType
,
image
.
data
);
}
}
catch
(
err
)
{
console
.
error
(
'Prompt or candidate was blocked:'
,
err
);
}
// Follow up requests do not need to specify the image again
const
followUpResult
=
await
chat
.
sendMessage
(
"But make it old-school line drawing style"
);
// Request and inspect the returned image
try
{
const
followUpInlineDataParts
=
followUpResult
.
response
.
inlineDataParts
();
if
(
followUpInlineDataParts
?
.[
0
])
{
// Inspect the generated image
const
followUpImage
=
followUpInlineDataParts
[
0
].
inlineData
;
console
.
log
(
followUpImage
.
mimeType
,
followUpImage
.
data
);
}
}
catch
(
err
)
{
console
.
error
(
'Prompt or candidate was blocked:'
,
err
);
}
Dart
import
'package:firebase_ai/firebase_ai.dart'
;
import
'package:firebase_core/firebase_core.dart'
;
import
'firebase_options.dart'
;
await
Firebase
.
initializeApp
(
options:
DefaultFirebaseOptions
.
currentPlatform
,
);
// Initialize the Gemini Developer API backend service
// Create a `GenerativeModel` instance with a Gemini model that supports image output
final
model
=
FirebaseAI
.
googleAI
().
generativeModel
(
model:
'gemini-2.5-flash-image'
,
// Configure the model to respond with text and images (required)
generationConfig:
GenerationConfig
(
responseModalities:
[
ResponseModalities
.
text
,
ResponseModalities
.
image
]),
);
// Prepare an image for the model to edit
final
image
=
await
File
(
'scones.jpg'
).
readAsBytes
();
final
imagePart
=
InlineDataPart
(
'image/jpeg'
,
image
);
// Provide an initial text prompt instructing the model to edit the image
final
prompt
=
TextPart
(
"Edit this image to make it look like a cartoon"
);
// Initialize the chat
final
chat
=
model
.
startChat
();
// To generate an initial response, send a user message with the image and text prompt
final
response
=
await
chat
.
sendMessage
([
Content
.
multi
([
prompt
,
imagePart
])
]);
// Inspect the returned image
if
(
response
.
inlineDataParts
.
isNotEmpty
)
{
final
imageBytes
=
response
.
inlineDataParts
[
0
].
bytes
;
// Process the image
}
else
{
// Handle the case where no images were generated
print
(
'Error: No images were generated.'
);
}
// Follow up requests do not need to specify the image again
final
followUpResponse
=
await
chat
.
sendMessage
([
Content
.
text
(
"But make it old-school line drawing style"
)
]);
// Inspect the returned image
if
(
followUpResponse
.
inlineDataParts
.
isNotEmpty
)
{
final
followUpImageBytes
=
response
.
inlineDataParts
[
0
].
bytes
;
// Process the image
}
else
{
// Handle the case where no images were generated
print
(
'Error: No images were generated.'
);
}
Unity
using
Firebase
;
using
Firebase.AI
;
// Initialize the Gemini Developer API backend service
// Create a `GenerativeModel` instance with a Gemini model that supports image output
var
model
=
FirebaseAI
.
GetInstance
(
FirebaseAI
.
Backend
.
GoogleAI
()).
GetGenerativeModel
(
modelName
:
"gemini-2.5-flash-image"
,
// Configure the model to respond with text and images (required)
generationConfig
:
new
GenerationConfig
(
responseModalities
:
new
[]
{
ResponseModality
.
Text
,
ResponseModality
.
Image
})
);
// Prepare an image for the model to edit
var
imageFile
=
System
.
IO
.
File
.
ReadAllBytes
(
System
.
IO
.
Path
.
Combine
(
UnityEngine
.
Application
.
streamingAssetsPath
,
"scones.jpg"
));
var
image
=
ModelContent
.
InlineData
(
"image/jpeg"
,
imageFile
);
// Provide an initial text prompt instructing the model to edit the image
var
prompt
=
ModelContent
.
Text
(
"Edit this image to make it look like a cartoon."
);
// Initialize the chat
var
chat
=
model
.
StartChat
();
// To generate an initial response, send a user message with the image and text prompt
var
response
=
await
chat
.
SendMessageAsync
(
new
[]
{
prompt
,
image
});
// Inspect the returned image
var
imageParts
=
response
.
Candidates
.
First
().
Content
.
Parts
.
OfType
<
ModelContent
.
InlineDataPart
>
()
.
Where
(
part
=>
part
.
MimeType
==
"image/png"
);
// Load the image into a Unity Texture2D object
UnityEngine
.
Texture2D
texture2D
=
new
(
2
,
2
);
if
(
texture2D
.
LoadImage
(
imageParts
.
First
().
Data
.
ToArray
()))
{
// Do something with the image
}
// Follow up requests do not need to specify the image again
var
followUpResponse
=
await
chat
.
SendMessageAsync
(
"But make it old-school line drawing style"
);
// Inspect the returned image
var
followUpImageParts
=
followUpResponse
.
Candidates
.
First
().
Content
.
Parts
.
OfType
<
ModelContent
.
InlineDataPart
>
()
.
Where
(
part
=>
part
.
MimeType
==
"image/png"
);
// Load the image into a Unity Texture2D object
UnityEngine
.
Texture2D
followUpTexture2D
=
new
(
2
,
2
);
if
(
followUpTexture2D
.
LoadImage
(
followUpImageParts
.
First
().
Data
.
ToArray
()))
{
// Do something with the image
}
Stream the response
Before trying this sample, complete the Before you begin
section of this guide
to set up your project and app.
In that section, you'll also click a button for your chosen Gemini API provider so that you see provider-specific content on this page.
In that section, you'll also click a button for your chosen Gemini API provider so that you see provider-specific content on this page.
You can achieve faster interactions by not waiting for the entire result from
the model generation, and instead use streaming to handle partial results.
To stream the response, call sendMessageStream()
.
View example: Stream chat responses
Swift
You can call startChat()
and sendMessageStream()
to stream responses from the model:
import
FirebaseAILogic
// Initialize the Gemini Developer API backend service
let
ai
=
FirebaseAI
.
firebaseAI
(
backend
:
.
googleAI
())
// Create a `GenerativeModel` instance with a model that supports your use case
let
model
=
ai
.
generativeModel
(
modelName
:
"gemini-2.5-flash"
)
// Optionally specify existing chat history
let
history
=
[
ModelContent
(
role
:
"user"
,
parts
:
"Hello, I have 2 dogs in my house."
),
ModelContent
(
role
:
"model"
,
parts
:
"Great to meet you. What would you like to know?"
),
]
// Initialize the chat with optional chat history
let
chat
=
model
.
startChat
(
history
:
history
)
// To stream generated text output, call sendMessageStream and pass in the message
let
contentStream
=
try
chat
.
sendMessageStream
(
"How many paws are in my house?"
)
for
try
await
chunk
in
contentStream
{
if
let
text
=
chunk
.
text
{
print
(
text
)
}
}
Kotlin
You can call startChat()
and sendMessageStream()
to stream responses from the model:
// Initialize the Gemini Developer API backend service
// Create a `GenerativeModel` instance with a model that supports your use case
val
model
=
Firebase
.
ai
(
backend
=
GenerativeBackend
.
googleAI
())
.
generativeModel
(
"gemini-2.5-flash"
)
// Initialize the chat
val
chat
=
model
.
startChat
(
history
=
listOf
(
content
(
role
=
"user"
)
{
text
(
"Hello, I have 2 dogs in my house."
)
},
content
(
role
=
"model"
)
{
text
(
"Great to meet you. What would you like to know?"
)
}
)
)
chat
.
sendMessageStream
(
"How many paws are in my house?"
).
collect
{
chunk
->
print
(
chunk
.
text
)
}
Java
You can call startChat()
and sendMessageStream()
to stream responses from the model:
Publisher
type from the Reactive Streams library
.
// Initialize the Gemini Developer API backend service
// Create a `GenerativeModel` instance with a model that supports your use case
GenerativeModel
ai
=
FirebaseAI
.
getInstance
(
GenerativeBackend
.
googleAI
())
.
generativeModel
(
"gemini-2.5-flash"
);
// Use the GenerativeModelFutures Java compatibility layer which offers
// support for ListenableFuture and Publisher APIs
GenerativeModelFutures
model
=
GenerativeModelFutures
.
from
(
ai
);
// (optional) Create previous chat history for context
Content
.
Builder
userContentBuilder
=
new
Content
.
Builder
();
userContentBuilder
.
setRole
(
"user"
);
userContentBuilder
.
addText
(
"Hello, I have 2 dogs in my house."
);
Content
userContent
=
userContentBuilder
.
build
();
Content
.
Builder
modelContentBuilder
=
new
Content
.
Builder
();
modelContentBuilder
.
setRole
(
"model"
);
modelContentBuilder
.
addText
(
"Great to meet you. What would you like to know?"
);
Content
modelContent
=
userContentBuilder
.
build
();
List<Content>
history
=
Arrays
.
asList
(
userContent
,
modelContent
);
// Initialize the chat
ChatFutures
chat
=
model
.
startChat
(
history
);
// Create a new user message
Content
.
Builder
messageBuilder
=
new
Content
.
Builder
();
messageBuilder
.
setRole
(
"user"
);
messageBuilder
.
addText
(
"How many paws are in my house?"
);
Content
message
=
messageBuilder
.
build
();
// Send the message
Publisher<GenerateContentResponse>
streamingResponse
=
chat
.
sendMessageStream
(
message
);
final
String
[]
fullResponse
=
{
""
};
streamingResponse
.
subscribe
(
new
Subscriber<GenerateContentResponse>
()
{
@Override
public
void
onNext
(
GenerateContentResponse
generateContentResponse
)
{
String
chunk
=
generateContentResponse
.
getText
();
fullResponse
[
0
]
+=
chunk
;
}
@Override
public
void
onComplete
()
{
System
.
out
.
println
(
fullResponse
[
0
]
);
}
// ... other methods omitted for brevity
});
Web
You can call startChat()
and sendMessageStream()
to stream responses from the model:
import
{
initializeApp
}
from
"firebase/app"
;
import
{
getAI
,
getGenerativeModel
,
GoogleAIBackend
}
from
"firebase/ai"
;
// TODO(developer) Replace the following with your app's Firebase configuration
// See: https://firebase.google.com/docs/web/learn-more#config-object
const
firebaseConfig
=
{
// ...
};
// Initialize FirebaseApp
const
firebaseApp
=
initializeApp
(
firebaseConfig
);
// Initialize the Gemini Developer API backend service
const
ai
=
getAI
(
firebaseApp
,
{
backend
:
new
GoogleAIBackend
()
});
// Create a `GenerativeModel` instance with a model that supports your use case
const
model
=
getGenerativeModel
(
ai
,
{
model
:
"gemini-2.5-flash"
});
async
function
run
()
{
const
chat
=
model
.
startChat
({
history
:
[
{
role
:
"user"
,
parts
:
[{
text
:
"Hello, I have 2 dogs in my house."
}],
},
{
role
:
"model"
,
parts
:
[{
text
:
"Great to meet you. What would you like to know?"
}],
},
],
generationConfig
:
{
maxOutputTokens
:
100
,
},
});
const
msg
=
"How many paws are in my house?"
;
const
result
=
await
chat
.
sendMessageStream
(
msg
);
let
text
=
''
;
for
await
(
const
chunk
of
result
.
stream
)
{
const
chunkText
=
chunk
.
text
();
console
.
log
(
chunkText
);
text
+=
chunkText
;
}
}
run
();
Dart
You can call startChat()
and sendMessageStream()
to stream responses from the model:
import
'package:firebase_ai/firebase_ai.dart'
;
import
'package:firebase_core/firebase_core.dart'
;
import
'firebase_options.dart'
;
// Initialize FirebaseApp
await
Firebase
.
initializeApp
(
options:
DefaultFirebaseOptions
.
currentPlatform
,
);
// Initialize the Gemini Developer API backend service
// Create a `GenerativeModel` instance with a model that supports your use case
final
model
=
FirebaseAI
.
googleAI
().
generativeModel
(
model:
'gemini-2.5-flash'
);
final
chat
=
model
.
startChat
();
// Provide a prompt that contains text
final
prompt
=
[
Content
.
text
(
'Write a story about a magic backpack.'
)];
final
response
=
await
chat
.
sendMessageStream
(
prompt
);
await
for
(
final
chunk
in
response
)
{
print
(
chunk
.
text
);
}
Unity
You can call StartChat()
and SendMessageStreamAsync()
to stream responses from the model:
using
Firebase
;
using
Firebase.AI
;
// Initialize the Gemini Developer API backend service
var
ai
=
FirebaseAI
.
GetInstance
(
FirebaseAI
.
Backend
.
GoogleAI
());
// Create a `GenerativeModel` instance with a model that supports your use case
var
model
=
ai
.
GetGenerativeModel
(
modelName
:
"gemini-2.5-flash"
);
// Optionally specify existing chat history
var
history
=
new
[]
{
ModelContent
.
Text
(
"Hello, I have 2 dogs in my house."
),
new
ModelContent
(
"model"
,
new
ModelContent
.
TextPart
(
"Great to meet you. What would you like to know?"
)),
};
// Initialize the chat with optional chat history
var
chat
=
model
.
StartChat
(
history
);
// To stream generated text output, call SendMessageStreamAsync and pass in the message
var
responseStream
=
chat
.
SendMessageStreamAsync
(
"How many paws are in my house?"
);
await
foreach
(
var
response
in
responseStream
)
{
if
(
!
string
.
IsNullOrWhiteSpace
(
response
.
Text
))
{
UnityEngine
.
Debug
.
Log
(
response
.
Text
);
}
}
Learn how to choose a model appropriate for your use case and app.
