Setting up PocketSphinx library in my own Android App

Question

I am trying to implement Speech Recognition with the help of Pocket Sphinx Library.

What my approach was,

I just downloaded their demo project for Android. Imported it in Eclipse, did clean-build and run it on device. It ran successfully.

After this I copied the libs folder from demo project to my own project. I copied the assets folder contents as it is in my own project. Then I edited the digits.gram file contents as per this post.

Then implemented the Listener in my activity and added addKeywordSearch to it.

My Questions:

1. Is this approach correct to implement this library in our own projects? Can we just copy paste all the files, modify .gram files as per need and run it? Or we need to do some other steps to generate .gram files?

2. When I tried with the above mentioned approach, then project ran successfully on the device for a few times. But after that it started showing the following error.

   E/cmusphinx(10470): ERROR: "kws_search.c", line 158: The word '/1e-20/' is missing in the dictionary
   E/AndroidRuntime(10470): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.uwemo.myvdemo/com.uwemo.myvdemo.MainActivity}: java.lang.RuntimeException: Decoder_setSearch returned -1
   

However /1e-20/ exists in my digits.gram file.

digits.gram file contents:

up /1e-20/
down /1e-15/
left /1e-15/
right /1e-15/
here /1e-15/

3. I noticed one thing, when I do clean-build of demo project of Pocket Sphinx and run it, then it recreates digits.gram.md5 files. But when I copied pasted all in my own project and did its cleant-build then these files were not recreated. Is this normal?

4. Is it necessary to have all the files in our project as in the demo project? Or can I delete some unused files from my own project? Any list of necessary files (either in assets folder or libs or others) will be highly helpful.

Please let me know what approach should I have to successfully implement it in my own project.

My Activity Code

public class MainActivity extends Activity implements RecognitionListener{

    private static final String DIGITS_SEARCH = "digits";
    private SpeechRecognizer recognizer;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        try
        {
            Assets assets = new Assets(MainActivity.this);
            File assetDir = assets.syncAssets();
            setupRecognizer(assetDir);

            Toast.makeText(getApplicationContext(), "Speech Recognizer Started", Toast.LENGTH_SHORT).show();
        }
        catch (IOException e){
            e.printStackTrace();
        }
    }

    @Override
    public void onBeginningOfSpeech() {
        // TODO Auto-generated method stub

    }

    @Override
    public void onEndOfSpeech() {
        // TODO Auto-generated method stub
        reset();
    }

    @Override
    public void onPartialResult(Hypothesis arg0) {
        // TODO Auto-generated method stub

    }

    @Override
    public void onResult(Hypothesis hypothesis) {
        // TODO Auto-generated method stub
        if (hypothesis != null){
            String text = hypothesis.getHypstr();
            Toast.makeText(getApplicationContext(), "you got ::"+text, Toast.LENGTH_SHORT).show();
        }
    }

    private void setupRecognizer(File assetsDir){
        File modelsDir = new File(assetsDir, "models");

        recognizer = defaultSetup().setAcousticModel(new File(modelsDir, "hmm/en-us-semi"))
                                   .setDictionary(new File(modelsDir, "dict/cmu07a.dic"))
                                   .setRawLogDir(assetsDir).setKeywordThreshold(1e-20f)
                                   .getRecognizer();

        recognizer.addListener(this);

        File digitsGrammar = new File(modelsDir, "grammar/digits.gram");
        recognizer.addKeywordSearch(DIGITS_SEARCH, digitsGrammar);

        reset();
    }

    private void reset(){
        recognizer.stop();
        recognizer.startListening(DIGITS_SEARCH);
    }
}

My project structure is following