Speech Recognizer Android Example. I removed unrelated part of codes so it would not run if you just copy and paste it.

SpeechRecognizerExample.java

// Ommitted ...
public class MainActivity extends AppCompatActivity

    implements NavigationView.OnNavigationItemSelectedListener {

    SpeechRecognizer mSpeech = null;
    Intent mIntent;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        
        // Some UI Init code goes here ...

        //////////////////////////////////////////////////////////////////////////////////////
        // Note:
        // 1. Under <manifest>
        // <uses-permission android:name="android.permission.RECORD_AUDIO" />
        // 2. Then go to settings > Apps > Select the app > Permission > Turn on the Audio
        //////////////////////////////////////////////////////////////////////////////////////


        mSpeech = SpeechRecognizer.createSpeechRecognizer(this.getApplicationContext());
        mIntent = new Intent(RecognizerIntent.ACTION_RECOGNIZE_SPEECH);
        mIntent.putExtra(RecognizerIntent.EXTRA_LANGUAGE_MODEL, RecognizerIntent.LANGUAGE_MODEL_FREE_FORM);

        final Button btnToggle = (Button)findViewById(R.id.btnToggle);
        btnToggle.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                if (btnToggle.getText() == "Start"){
                    btnToggle.setText("Stop");
                    mSpeech.startListening(mIntent);
                }
                else {
                    btnToggle.setText("Start");
                    mSpeech.stopListening();
                }
            }
        });

        final TextView tvResult = (TextView)findViewById(R.id.tvResult);
        tvResult.setText("Click Start");
        mSpeech.setRecognitionListener(new RecognitionListener() {
            @Override
            public void onReadyForSpeech(Bundle bundle) {
                Log.v("myapp","onReadyForSpeech");
                tvResult.setText("Ready");
            }

            @Override
            public void onBeginningOfSpeech() {
                Log.v("myapp","onBeginningOfSpeech");
            }

            @Override
            public void onRmsChanged(float v) {
                Log.v("myapp","onRmsChanged:" + v);
                if ((new Random()).nextInt(2) == 1) {
                    tvResult.setBackgroundColor(Color.LTGRAY);
                }
                else {
                    tvResult.setBackgroundColor(Color.GRAY);
                }
            }

            @Override
            public void onBufferReceived(byte[] bytes) {
                Log.v("myapp","onBufferReceived: " + bytes.length);
            }

            @Override
            public void onEndOfSpeech() {
                Log.v("myapp","onEndOfSpeech");
                tvResult.setBackgroundColor(Color.WHITE);
            }

            @Override
            public void onError(int i) {
                //http://developer.android.com/reference/android/speech/SpeechRecognizer.html#ERROR_INSUFFICIENT_PERMISSIONS
                Log.v("myapp","error: " + i);
                tvResult.setBackgroundColor(Color.WHITE);
            }

            @Override
            public void onResults(Bundle bundle) {
                ArrayList<String> words = bundle.getStringArrayList(SpeechRecognizer.RESULTS_RECOGNITION);
                float[] scores = bundle.getFloatArray(android.speech.SpeechRecognizer.CONFIDENCE_SCORES);
                Log.v("myapp",words.get(0));
                //Log.v("myapp",scores[0]));

                tvResult.setText(words.get(0));
                tvResult.setBackgroundColor(Color.WHITE);
            }

            @Override
            public void onPartialResults(Bundle bundle) {
                Log.v("myapp","onPartialResults");
                ArrayList<String> words = bundle.getStringArrayList(SpeechRecognizer.RESULTS_RECOGNITION);
                tvResult.setText(words.get(0));
                tvResult.setBackgroundColor(Color.WHITE);
            }

            @Override
            public void onEvent(int i, Bundle bundle) {
                Log.v("myapp","onEvent:" + i);

            }
        });




    }

 
}