HIGHLIGHTS
Our target device must have at least one application that can process the Intent for speech recognition, which is called by theRecognizerIntent.ACTION_RECOGNIZE_SPEECH action.
Android can’t recognize speech, so a typical Android device cannot recognize speech either.
Or, is there a way it can? The easiest way is to ask another application to do the recognition for us. Asking another application to do something in Android is called
using intents.
One such app is
Google Voice Search. It is one of the best recognizers available for Android and supports a lot of languages. This service requires Internet connection because the voice recognition occurs on Google servers. This app has a very simple
Activity that informs users they can speak. The moment the user stops talking, the dialog is closed and our application (intent caller) receives an array of strings with the recognized speech.
A voice recognition sample
Let’s write a little sample app that demonstrates using voice search in applications.
Our application needs to do these things:
- Receive a request for voice recognition
- Check the availability of application for speech recognizing
- If speech recognizing is available, then call the intent for it and receive the results
- If speech recognizing is not available, then show the dialog for installing Google Voice Search and redirect the user to Google Play, if he wants
First, we create a class that implements the logic for speech recognition. Call this class SpeechRecognitionHelper where we declare a static, public function run() that will receive a request for launching a recognition:
02 | * A helper class for speech recognition |
04 | public class SpeechRecognitionHelper { |
07 | * Running the recognition process. Checks availability of recognition Activity, |
08 | * If Activity is absent, send user to Google Play to install Google Voice Search. |
09 | * If Activity is available, send Intent for running. |
11 | * @param callingActivity = Activity, that initializing recognition process |
13 | public static void run(Activity callingActivity) { |
14 | // check if there is recognition Activity |
15 | if (isSpeechRecognitionActivityPresented(callingActivity) == true) { |
16 | // if yes – running recognition |
17 | startRecognition(callingActivity); |
19 | // if no, then showing notification to install Voice Search |
20 | Toast.makeText(callingActivity, "In order to activate speech recognition you must install "Google Voice Search"", Toast.LENGTH_LONG).show(); |
21 | // start installing process |
22 | installGoogleVoiceSearch(callingActivity); |
As you can see, besides the run() function we need to implement three other functions:
- isSpeechRecognitionActivityPresented – checks if the speech recognition application is present on the system
- installGoogleVoiceSearch – initializes the Google Voice Search installation process
- startRecognition – prepares the appropriate Intent and runs the recognition
To check if the device has an application for speech recognition, we can use the
queryIntentActivities method in class
PackageManager. This method gives a list of activities that can process the specified Intent. To receive an instance of the PackageManager, we can use
getPackageManager.
Our code is shown below:
isSpeechRecognitionActivityPresented
02 | * Checks availability of speech recognizing Activity |
04 | * @param callerActivity – Activity that called the checking |
05 | * @return true – if Activity there available, false – if Activity is absent |
07 | private static boolean isSpeechRecognitionActivityPresented(Activity callerActivity) { |
09 | // getting an instance of package manager |
10 | PackageManager pm = callerActivity.getPackageManager(); |
11 | // a list of activities, which can process speech recognition Intent |
12 | List activities = pm.queryIntentActivities(new Intent(RecognizerIntent.ACTION_RECOGNIZE_SPEECH), 0); |
14 | if (activities.size() != 0) { // if list not empty |
15 | return true; // then we can recognize the speech |
17 | } catch (Exception e) { |
21 | return false; // we have no activities to recognize the speech |
Now implement the startRecognition function. This function will form the appropriate Intent for launching the speech recognition Activity. You can find detailed information for how to do it on documentation page.
Source code:
02 | * Send an Intent with request on speech |
03 | * @param callerActivity - Activity, that initiated a request |
05 | private static void startRecognitionActivity(Activity callerActivity) { |
07 | // creating an Intent with “RecognizerIntent.ACTION_RECOGNIZE_SPEECH” action |
08 | Intent intent = new Intent(RecognizerIntent.ACTION_RECOGNIZE_SPEECH); |
10 | // giving additional parameters: |
11 | intent.putExtra(RecognizerIntent.EXTRA_PROMPT, "Select an application"); // user hint |
12 | intent.putExtra(RecognizerIntent.EXTRA_LANGUAGE_MODEL, RecognizerIntent.LANGUAGE_MODEL_WEB_SEARCH); // setting recognition model, optimized for short phrases – search queries |
13 | intent.putExtra(RecognizerIntent.EXTRA_MAX_RESULTS, 1); // quantity of results we want to receive |
14 | //choosing only 1st - the most relevant |
16 | // start Activity ant waiting the result |
17 | ownerActivity.startActivityForResult(intent, SystemData.VOICE_RECOGNITION_REQUEST_CODE); |
And last, we’ll implement the installGoogleVoiceSearch. This function will show the dialog, asking the user if he wants to install Google Voice Search and send him to Google Play, if he does.
02 | * Asking the permission for installing Google Voice Search. |
03 | * If permission granted – sent user to Google Play |
04 | * @param callerActivity – Activity, that initialized installing |
06 | private static void installGoogleVoiceSearch(final Activity ownerActivity) { |
08 | // creating a dialog asking user if he want |
09 | // to install the Voice Search |
10 | Dialog dialog = new AlertDialog.Builder(ownerActivity) |
11 | .setMessage("For recognition it’s necessary to install "Google Voice Search"") // dialog message |
12 | .setTitle("Install Voice Search from Google Play?") // dialog header |
13 | .setPositiveButton("Install", new DialogInterface.OnClickListener() { // confirm button |
15 | // Install Button click handler |
17 | public void onClick(DialogInterface dialog, int which) { |
19 | // creating an Intent for opening applications page in Google Play |
20 | // Voice Search package name: com.google.android.voicesearch |
22 | // setting flags to avoid going in application history (Activity call stack) |
23 | intent.setFlags(Intent.FLAG_ACTIVITY_NO_HISTORY | Intent.FLAG_ACTIVITY_CLEAR_WHEN_TASK_RESET); |
25 | ownerActivity.startActivity(intent); |
26 | } catch (Exception ex) { |
27 | // if something going wrong |
32 | .setNegativeButton("Cancel", null) // cancel button |
35 | dialog.show(); // showing dialog |
That’s about it. We run the speech recognition Activity. Then request the user’s permission to install Voice Search and send him to Google Play if he consents. One thing we still need to do and that is gather the voice recognition results.
We send a request using the
startActivityForResult function to gather results of the launched Activity. We also need to redefine a
OnActivityResultmethod in our intent caller Activity. This can be done this way:
01 | // Activity Results handler |
03 | public void onActivityResult(int requestCode, int resultCode, Intent data) { |
05 | // if it’s speech recognition results |
06 | // and process finished ok |
07 | if (requestCode == SystemData.VOICE_RECOGNITION_REQUEST_CODE && resultCode == RESULT_OK) { |
09 | // receiving a result in string array |
10 | // there can be some strings because sometimes speech recognizing inaccurate |
11 | // more relevant results in the beginning of the list |
12 | ArrayList matches = data.getStringArrayListExtra(RecognizerIntent.EXTRA_RESULTS); |
14 | // in “matches” array we holding a results... let’s show the most relevant |
15 | if (matches.size() > 0) Toast.makeText(this, matches.get(0), Toast.LENGTH_LONG).show(); |
18 | super.onActivityResult(requestCode, resultCode, data); |
Now we’re ready
The created class SpeechRecognitionHelper allows us to perform a speech recognition request by calling only one function run().
All that is needed for adding a recognition feature is to add this class in our project and call the run function in needed place. And then implement processing text results by redefining the onActivityResult method for the Activity that initiated the recognition call.
For additional information you can look at the
Android Developers website. Here, you’ll find good
examples showing how to do voice recognition, and importantly, how to get the available language list. You will need this list if you want to recognize a language other than the user’s default locale.
For fast integration of voice input in to your app, you can download and use this code for the
SpeechRecognitionHelper class.