如何从另一个活动中调用TextToSpeech活动？

Question

I have an activity ( MainActivity ) that implements TextToSpeech and works perfectly. When a button's onClick is called, it speaks whatever is typed in EditText .

MainActivity:

public class MainActivity extends AppCompatActivity implements TextToSpeech.OnInitListener{

    private TextToSpeech engine;
    private EditText text;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        text = (EditText) findViewById(R.id.text);
        engine = new TextToSpeech(this, this);

        Intent i=getIntent();
        Bundle b=i.getExtras();
        word=b.getString("word");
        speakText2(word);
    }

    // speakText is called by onClick button
    public void speakText(View v) {
        String textContents = text.getText().toString();
        engine.speak(textContents, TextToSpeech.QUEUE_FLUSH, null, null);
    }

    public void speakText2(String textContents) {
        engine.speak(textContents, TextToSpeech.QUEUE_ADD, null, null);
    }

    @Override
    public void onInit(int i) {
        if (i == TextToSpeech.SUCCESS) {
            //Setting speech Language
            engine.setLanguage(Locale.ENGLISH);
            engine.setPitch(1);
        }
    }
}

Now, I want to call MainActivity from another activity and pass a string to speak up. I tried:

MainActivity mainactivity = new MainActivity();
String word;
word = "speak";
mainactivity.speakText2(word); // Error

But, getting error:

Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'int android.speech.tts.TextToSpeech.speak(java.lang.CharSequence, int, android.os.Bundle, java.lang.String)' on a null object reference
at MainActivity.speakText2(TTSEngine.java:53)

I tried using intent from another activity:

Intent intent = new Intent(this, MainActivity.class);
intent.putExtra("word", word);
startActivity(intent);

But, getting error:

I/TextToSpeech: Sucessfully bound to com.google.android.tts
W/TextToSpeech: speak failed: not bound to TTS engine
W/TextToSpeech: speak failed: not bound to TTS engine
W/TextToSpeech: speak failed: not bound to TTS engine
I/TextToSpeech: Connected to ComponentInfo{com.google.android.tts/com.google.android.tts.service.GoogleTTSService}
I/TextToSpeech: Set up connection to ComponentInfo{com.google.android.tts/com.google.android.tts.service.GoogleTTSService}

I tried to implement TextToSpeech in the activity I want to use it in. But, it does not work for the first time I call speakText2 and give error:

W/TextToSpeech: speak failed: not bound to TTS engine
I/TextToSpeech: Connected to ComponentInfo{com.google.android.tts/com.google.android.tts.service.GoogleTTSService}
I/TextToSpeech: Set up connection to ComponentInfo{com.google.android.tts/com.google.android.tts.service.GoogleTTSService}

For rest of the time it work perfectly. Any idea how to fix this?

Answer 1

You can only let the engine speak, after onInit is done, so do following in onInit():

if (status == TextToSpeech.SUCCESS) { speakText2(word);

}

Answer 2

You have to use an Intent to start an Activity . See https://developer.android.com/training/basics/firstapp/starting-activity.html

When you create your Activity instance manually the onCreate method is not called (and any other lifecycle methods) - that's why you're getting an NPE accessing your engine property - it wasn't initialized.