Android Java TTS“永不完成”

Question

我已经多次问过这个问题但是他们中的任何一个实际上都没有帮助。当我启动tts时，会调用UtteranceProgressListener的onStart，但永远不会调用onEnd。

TTSClass.java

package com.michaelhoots.ttsapp;
import android.content.*;
import android.media.*;
import android.speech.tts.*;
import android.widget.*;
import java.util.*;

public class TTSClass {
  private Context ctx = null;
  private TextToSpeech tts = null;
  private TextToSpeech.OnInitListener onInitListener = null;
  private UtteranceProgressListener utteranceProgressListener = null;
  private String toSpeak = "";

  // handle start/stop
  private void handleStart() {
    HashMap<String, String> map = new HashMap<String, String>();
    map.put(TextToSpeech.Engine.KEY_PARAM_SESSION_ID, "TTS_ID");
    tts.setLanguage(Locale.US);
    tts.speak(toSpeak, TextToSpeech.QUEUE_FLUSH, map);
  }
  private void handleStop() {
    tts.stop();
    tts.shutdown();
    tts = null;
    toSpeak = "";
  }

  // speak
  public void speak(final String str) {
    toSpeak = str;
    onInitListener = new TextToSpeech.OnInitListener() {
      @Override
      public void onInit(int status) {
        if (status != TextToSpeech.ERROR) {
          handleStart();
        }
      }
    };
    tts = new TextToSpeech(ctx.getApplicationContext(), onInitListener);
    tts.setOnUtteranceProgressListener(utteranceProgressListener);
  }

  // constructor
  public TTSClass(Context context) {
    ctx = context;
    utteranceProgressListener = new UtteranceProgressListener() {
      @Override
      public void onStart(String id) {
        Toast.makeText(ctx, "Speech Started", Toast.LENGTH_SHORT).show();
      }

      @Override
      public void onDone(String id) {
        handleStop();
        Toast.makeText(ctx, "Speech Finished", Toast.LENGTH_SHORT).show();
      }

      @Override
      public void onError(String id) {}
    };
  }
}

当我打电话

speak("Text To Speech");

调用“onStart”方法并显示toast。但是，永远不会调用“onDone”方法，也不会显示其toast。我在这里做错了什么？