Android - 需要一個活動，但不想進行一項活動？

Question

我想創建一個使用textToSpeak的應用程序。顯然textToSpeak必須在一個活動中使用才能工作。

但是我不能在正常的java類中使用textToSpeak，所以我可以在當前正在運行的活動中實例化它並調用一個方法，使textToSpeech能夠發出特定的文本。

我設法讓TTS在一個單獨的項目時工作，它是運行的活動，但是我不能讓它在AA不同的一個實例...

說話類（持有TTS，有問題行是「私人文字轉語音TTS =新的文字轉語音（這一點，這一點）;」 - 提供了一個未捕獲的異常

import java.util.Locale; 

import android.app.Activity; 
import android.os.Bundle; 
import android.speech.tts.TextToSpeech; 
import android.util.Log; 

public class Speech extends Activity implements TextToSpeech.OnInitListener { 

    private TextToSpeech tts = new TextToSpeech(this, this); 
    private String toRead; 

    public void speak() 
    { 
     speakOut(); 
    } 

    public void changeText(String changeTo) 
    { 
     toRead = changeTo; 
    } 

    @Override 
    public void onDestroy() { 
     // Don't forget to shutdown tts! 
     if (tts != null) { 
      tts.stop(); 
      tts.shutdown(); 
     } 
     super.onDestroy(); 
    } 


    public void onInit(int status) { 

     if (status == TextToSpeech.SUCCESS) { 

      int result = tts.setLanguage(Locale.US); 

      if (result == TextToSpeech.LANG_MISSING_DATA 
        || result == TextToSpeech.LANG_NOT_SUPPORTED) { 
       Log.e("TTS", "This Language is not supported"); 
      } else { 
       speakOut(); 
      } 

     } else { 
      Log.e("TTS", "Initilization Failed!"); 
     } 

    } 

    private void speakOut() { 
     tts.speak(toRead, TextToSpeech.QUEUE_FLUSH, null); 
     } 
    } 

運行活動（編輯，以顯示我要如何使用語音類）

public class Text_entry extends Activity implements OnTouchListener{ 
private Speech speech = new Speech(); 

public boolean onTouch(View v, MotionEvent event) { 
speech.changeText(toRead); 
     speech.speak(); 
} 
} 

這個設置對其他對象來說工作得很好，因爲TTS需要成爲一個活動的一部分（如果語言沒有擴展活動，它是無法識別的）我似乎沒有工作。任何人都可以提供解決方案嗎？

logcat的

02-16 16:52:46.698: D/AndroidRuntime(22541): Shutting down VM 
02-16 16:52:46.698: W/dalvikvm(22541): threadid=1: thread exiting with uncaught exception (group=0x415fe300) 
02-16 16:52:46.703: E/AndroidRuntime(22541): FATAL EXCEPTION: main 
02-16 16:52:46.703: E/AndroidRuntime(22541): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{org.BT/org.BT.Text_entry}: java.lang.NullPointerException 
02-16 16:52:46.703: E/AndroidRuntime(22541): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2024) 
02-16 16:52:46.703: E/AndroidRuntime(22541): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2125) 
02-16 16:52:46.703: E/AndroidRuntime(22541): at android.app.ActivityThread.access$600(ActivityThread.java:140) 
02-16 16:52:46.703: E/AndroidRuntime(22541): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1227) 
02-16 16:52:46.703: E/AndroidRuntime(22541): at android.os.Handler.dispatchMessage(Handler.java:99) 
02-16 16:52:46.703: E/AndroidRuntime(22541): at android.os.Looper.loop(Looper.java:137) 
02-16 16:52:46.703: E/AndroidRuntime(22541): at android.app.ActivityThread.main(ActivityThread.java:4898) 
02-16 16:52:46.703: E/AndroidRuntime(22541): at java.lang.reflect.Method.invokeNative(Native Method) 
02-16 16:52:46.703: E/AndroidRuntime(22541): at java.lang.reflect.Method.invoke(Method.java:511) 
02-16 16:52:46.703: E/AndroidRuntime(22541): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1006) 
02-16 16:52:46.703: E/AndroidRuntime(22541): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:773) 
02-16 16:52:46.703: E/AndroidRuntime(22541): at dalvik.system.NativeStart.main(Native Method) 
02-16 16:52:46.703: E/AndroidRuntime(22541): Caused by: java.lang.NullPointerException 
02-16 16:52:46.703: E/AndroidRuntime(22541): at android.content.ContextWrapper.getContentResolver(ContextWrapper.java:91) 
02-16 16:52:46.703: E/AndroidRuntime(22541): at android.speech.tts.TtsEngines.getDefaultEngine(TtsEngines.java:75) 
02-16 16:52:46.703: E/AndroidRuntime(22541): at android.speech.tts.TextToSpeech.getDefaultEngine(TextToSpeech.java:1235) 
02-16 16:52:46.703: E/AndroidRuntime(22541): at android.speech.tts.TextToSpeech.initTts(TextToSpeech.java:595) 
02-16 16:52:46.703: E/AndroidRuntime(22541): at android.speech.tts.TextToSpeech.<init>(TextToSpeech.java:553) 
02-16 16:52:46.703: E/AndroidRuntime(22541): at android.speech.tts.TextToSpeech.<init>(TextToSpeech.java:527) 
02-16 16:52:46.703: E/AndroidRuntime(22541): at android.speech.tts.TextToSpeech.<init>(TextToSpeech.java:512) 
02-16 16:52:46.703: E/AndroidRuntime(22541): at org.BT.Speech.<init>(Speech.java:12) 
02-16 16:52:46.703: E/AndroidRuntime(22541): at org.BT.Text_entry.<init>(Text_entry.java:48) 
02-16 16:52:46.703: E/AndroidRuntime(22541): at java.lang.Class.newInstanceImpl(Native Method) 
02-16 16:52:46.703: E/AndroidRuntime(22541): at java.lang.Class.newInstance(Class.java:1319) 
02-16 16:52:46.703: E/AndroidRuntime(22541): at android.app.Instrumentation.newActivity(Instrumentation.java:1057) 
02-16 16:52:46.703: E/AndroidRuntime(22541): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2015) 
02-16 16:52:46.703: E/AndroidRuntime(22541): ... 11 more 

Answer 1

不要延長Activity。傳遞一個Context給構造來代替：

public class Speech implements TextToSpeech.OnInitListener { 
    private Context mContext; 
    private TextToSpeech tts; 

    public Speech(Context c) { 
     mContext = c; 
     tts = new TextToSpeech(c, this); 
    } 

    // Rest of class 
} 

然後構建它像這樣：

public class Text_entry extends Activity implements OnTouchListener{ 
    private Speech speech; 

    public void onCreate(Bundled saved) { 
     super.onCreate(saved); 
     speech = new Speech(this); 
    } 
    public boolean onTouch(View v, MotionEvent event) { 
     speech.changeText(toRead); 
     speech.speak(); 
    } 
}