You can use ML Kit to translate text between languages. ML Kit currently supports translation between 59 languages .
Before you begin
- If you haven't already, add Firebase to your Android project .
- Add the dependencies for the ML Kit Android libraries to your module
(app-level) Gradle file (usually
app/build.gradle):apply plugin : ' com . android . application ' apply plugin : ' com . google . gms . google - services ' dependencies { // ... implementation ' com . google . firebase : firebase - ml - natural - language : 22.0.0 ' implementation ' com . google . firebase : firebase - ml - natural - language - translate - model : 20.0.8 ' }
Translate a string of text
To translate a string between two languages:
-
Create a
FirebaseTranslatorobject, configuring it with the source and target languages:Java
// Create an English-German translator: FirebaseTranslatorOptions options = new FirebaseTranslatorOptions . Builder () . setSourceLanguage ( FirebaseTranslateLanguage . EN ) . setTargetLanguage ( FirebaseTranslateLanguage . DE ) . build (); final FirebaseTranslator englishGermanTranslator = FirebaseNaturalLanguage . getInstance (). getTranslator ( options );Kotlin
// Create an English-German translator: val options = FirebaseTranslatorOptions . Builder () . setSourceLanguage ( FirebaseTranslateLanguage . EN ) . setTargetLanguage ( FirebaseTranslateLanguage . DE ) . build () val englishGermanTranslator = FirebaseNaturalLanguage . getInstance (). getTranslator ( options )If you don't know the language of the input text, you can use the language identification API first. (But be sure you don't keep too many language models on the device at once.)
-
Make sure the required translation model has been downloaded to the device. Don't call
translate()until you know the model is available.Java
FirebaseModelDownloadConditions conditions = new FirebaseModelDownloadConditions . Builder () . requireWifi () . build (); englishGermanTranslator . downloadModelIfNeeded ( conditions ) . addOnSuccessListener ( new OnSuccessListener<Void> () { @Override public void onSuccess ( Void v ) { // Model downloaded successfully. Okay to start translating. // (Set a flag, unhide the translation UI, etc.) } }) . addOnFailureListener ( new OnFailureListener () { @Override public void onFailure ( @NonNull Exception e ) { // Model couldn’t be downloaded or other internal error. // ... } });Kotlin
englishGermanTranslator . downloadModelIfNeeded () . addOnSuccessListener { // Model downloaded successfully. Okay to start translating. // (Set a flag, unhide the translation UI, etc.) } . addOnFailureListener { exception - > // Model couldn’t be downloaded or other internal error. // ... }Language models are around 30MB, so don't download them unnecessarily, and only download them using WiFi, unless the user has specified otherwise. You should also delete unneeded models. See Explicitly manage translation models .
-
After you confirm the model has been downloaded, pass a string of text in the source language to
translate():Java
englishGermanTranslator . translate ( text ) . addOnSuccessListener ( new OnSuccessListener<String> () { @Override public void onSuccess ( @NonNull String translatedText ) { // Translation successful. } }) . addOnFailureListener ( new OnFailureListener () { @Override public void onFailure ( @NonNull Exception e ) { // Error. // ... } });Kotlin
englishGermanTranslator . translate ( text ) . addOnSuccessListener { translatedText - > // Translation successful. } . addOnFailureListener { exception - > // Error. // ... }The translated text, in the target language you configured, is passed to the success listener.
Explicitly manage translation models
When you use the translation API as described above, ML Kit automatically downloads language-specific translation models to the device as required. You can also explicitly manage the translation models you want available on the device by using ML Kit's translation model management API. This can be useful if you want to download models ahead of time, or delete unneeded models from the device.
Java
FirebaseModelManager
modelManager
=
FirebaseModelManager
.
getInstance
();
// Get translation models stored on the device.
modelManager
.
getDownloadedModels
(
FirebaseTranslateRemoteModel
.
class
)
.
addOnSuccessListener
(
new
OnSuccessListener<Set<FirebaseTranslateRemoteModel>
> ()
{
@Override
public
void
onSuccess
(
Set<FirebaseTranslateRemoteModel>
models
)
{
// ...
}
})
.
addOnFailureListener
(
new
OnFailureListener
()
{
@Override
public
void
onFailure
(
@NonNull
Exception
e
)
{
// Error.
}
});
// Delete the German model if it's on the device.
FirebaseTranslateRemoteModel
deModel
=
new
FirebaseTranslateRemoteModel
.
Builder
(
FirebaseTranslateLanguage
.
DE
).
build
();
modelManager
.
deleteDownloadedModel
(
deModel
)
.
addOnSuccessListener
(
new
OnSuccessListener<Void>
()
{
@Override
public
void
onSuccess
(
Void
v
)
{
// Model deleted.
}
})
.
addOnFailureListener
(
new
OnFailureListener
()
{
@Override
public
void
onFailure
(
@NonNull
Exception
e
)
{
// Error.
}
});
// Download the French model.
FirebaseTranslateRemoteModel
frModel
=
new
FirebaseTranslateRemoteModel
.
Builder
(
FirebaseTranslateLanguage
.
FR
).
build
();
FirebaseModelDownloadConditions
conditions
=
new
FirebaseModelDownloadConditions
.
Builder
()
.
requireWifi
()
.
build
();
modelManager
.
download
(
frModel
,
conditions
)
.
addOnSuccessListener
(
new
OnSuccessListener<Void>
()
{
@Override
public
void
onSuccess
(
Void
v
)
{
// Model downloaded.
}
})
.
addOnFailureListener
(
new
OnFailureListener
()
{
@Override
public
void
onFailure
(
@NonNull
Exception
e
)
{
// Error.
}
});
Kotlin
val
modelManager
=
FirebaseModelManager
.
getInstance
()
// Get translation models stored on the device.
modelManager
.
getDownloadedModels
(
FirebaseTranslateRemoteModel
::
class
.
java
)
.
addOnSuccessListener
{
models
-
>
// ...
}
.
addOnFailureListener
{
// Error.
}
// Delete the German model if it's on the device.
val
deModel
=
FirebaseTranslateRemoteModel
.
Builder
(
FirebaseTranslateLanguage
.
DE
).
build
()
modelManager
.
deleteDownloadedModel
(
deModel
)
.
addOnSuccessListener
{
// Model deleted.
}
.
addOnFailureListener
{
// Error.
}
// Download the French model.
val
frModel
=
FirebaseTranslateRemoteModel
.
Builder
(
FirebaseTranslateLanguage
.
FR
).
build
()
val
conditions
=
FirebaseModelDownloadConditions
.
Builder
()
.
requireWifi
()
.
build
()
modelManager
.
download
(
frModel
,
conditions
)
.
addOnSuccessListener
{
// Model downloaded.
}
.
addOnFailureListener
{
// Error.
}
