Creating Your Own Spelling Checker Service in Android

1. Create a spelling checker service class

Spell Suggestion @ Interesting Code

To create a spelling checker service, the first step is to create a spelling checker service class that extends android.service.textservice.SpellCheckerService.

For a working example of a spelling checker, you may want to take a look at the SampleSpellCheckerService class in the SpellChecker sample app, available from the Samples download package in the Android SDK.

2. Implement the required methods

Next, in your subclass of SpellCheckerService, implement the methods createSession() and onGetSuggestions(), as shown in the following code snippet:

@Override                                                                        public Session createSession() {                                             
    return new AndroidSpellCheckerSession();                                 }       
private static class AndroidSpellCheckerSession extends Session {            
    @Override                                                                
    public SuggestionsInfo onGetSuggestions(TextInfo textInfo, int suggestionsLimit) {
        SuggestionsInfo suggestionsInfo;
        ... // look up suggestions for TextInfo
        return suggestionsInfo;
    }      }

3. Register the spelling checker service in AndroidManifest.xml

In addition to implementing your subclass, you need to declare the spelling checker service in your manifest file. The declaration specifies the application, the service, and a metadata file that defines the Activity to use for controlling settings. Here’s an example:

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.android.samplespellcheckerservice">
    <application android:label="@string/app_name">
        <service 
            android:label="@string/app_name"    
            android:name=".SampleSpellCheckerService" 
            android:permission="android.permission.BIND_TEXT_SERVICE">
            <intent-filter>
                <action 
                    android:name="android.service.textservice.SpellCheckerService" />
            </intent-filter>
            <meta-data
                android:name="android.view.textservice.scs"
                android:resource="@xml/spellchecker" />
        </service>
    </application>
</manifest>

4. Create a metadata XML resource file

Last, create a metadata file for your spelling checker to define the Activity to use for controlling spelling checker settings. The metadata file can also define subtypes for the spelling checker. Place the file in the location specified in the 
element of the spelling checker declaration in the manifest file.

In the example below, the metadata file spellchecker.xml specifies the settings Activity asSpellCheckerSettingsActivity and includes subtypes to define the locales that the spelling checker can handle.

<spell-checker xmlns:android="http://schemas.android.com/apk/res/android"
    android:label="@string/spellchecker_name"
    android:settingsactivity="com.example.SpellCheckerSettingsActivity" />
    <subtype   
        android:label="@string/subtype_generic" 
        android:subtypeLocale="en" />
</spell-checker>

Bonus points: Add batch processing of multiple sentences

For faster, more accurate spell-checking, Android 4.1 (Jelly Bean) introduces APIs that let clients pass multiple sentences to your spelling checker at once.

To support sentence-level checking for multiple sentences in a single call, just override and implement the methodonGetSentenceSuggestionsMultiple(), as shown below. 

private static class AndroidSpellCheckerSession extends Session {                 
    @Override                                                                
    public SentenceSuggestionsInfo[] onGetSentenceSuggestionsMultiple(
          TextInfo[] textInfo, int suggestionsLimit) {
        SentenceSuggestionsInfo[] sentenceSuggestionsInfos;
        ... // look up suggestions for each TextInfo
        return sentenceSuggestionsInfos
    }      }

Documents and samples

If you’d like to learn more about how to use the spelling checker APIs, take a look at these documents and samples:

• Spelling Checker Framework API Guide — a developer guide covering the Spelling Checker API for clients and services.
• SampleSpellCheckerService sample app — helps you get started with your spelling checker service.
  
  • You can find the app at /samples/android-15/SpellChecker/SampleSpellCheckerService in the Samples download.
• HelloSpellChecker sample app — a basic app that uses a spelling checker.
  
  • You can find the app at /samples/android-15/SpellChecker/HelloSpellChecker in the Samples download.

To learn how to download sample apps for the Android SDK, see Samples.