主要问题是：
1）在初始化tts之前设置进度监听器。
2）尝试用后台线程制作Toast。
我还有其他建议的更改，但不是必需的：
public class MainActivity extends AppCompatActivity { String message = "How may I help you?"; String mostRecentUtteranceID; private TextToSpeech myTTS; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); myTTS = new TextToSpeech(this, new TextToSpeech.onInitListener() { @Override public void onInit(int status) { if(myTTS.getEngines().size() == 0){ Toast.makeText(MainActivity.this,"No Engines Installed",Toast.LENGTH_LONG).show(); }else{ if (status == TextToSpeech.SUCCESS){ ttsInitialized(); } } } }); } private void ttsInitialized() { // *** set UtteranceProgressListener AFTER tts is initialized *** myTTS.setonUtteranceProgressListener(new UtteranceProgressListener() { @Override public void onStart(String utteranceId) { } @Override // this method will always called from a background thread. public void onDone(String utteranceId) { // only respond to the most recent utterance if (!utteranceId.equals(mostRecentUtteranceID)) { Log.i("XXX", "onDone() blocked: utterance ID mismatch."); return; } // else continue... boolean wasCalledFromBackgroundThread = (Thread.currentThread().getId() != 1); Log.i("XXX", "was onDone() called on a background thread? : " + wasCalledFromBackgroundThread); Log.i("XXX", "onDone working."); // for demonstration only... avoid references to // MainActivity (unless you use a WeakReference) // inside the onDone() method, as it // can cause a memory leak. runonUiThread(new Runnable() { @Override public void run() { // *** toast will not work if called from a background thread *** Toast.makeText(MainActivity.this,"onDone working.",Toast.LENGTH_LONG).show(); } }); } @Override public void onError(String utteranceId) { } }); // set Language myTTS.setLanguage(Locale.US); // set unique utterance ID for each utterance mostRecentUtteranceID = (new Random().nextInt() % 9999999) + ""; // "" is String force // set params // *** this method will work for more devices: API 19+ *** HashMap<String, String> params = new HashMap<>(); params.put(TextToSpeech.Engine.KEY_PARAM_UTTERANCE_ID, mostRecentUtteranceID); myTTS.speak(message,TextToSpeech.QUEUE_FLUSH,params); }}
