的MediaPlayer的start（）/停止（）穆裏爲空

Question

我有一個活動，看起來像，

public class TestActivity extends Activity { 

    private SensorManager  mSensorManager; 
     private ShakeEventListener mSensorListener; 
    private MediaPlayer  mPlayer; 

    private boolean   mIsPlaying; 

    /** Called when the activity is first created. */ 
    @Override 
    public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     requestWindowFeature(Window.FEATURE_NO_TITLE); 

     this.getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,WindowManager.LayoutParams.FLAG_FULLSCREEN); 

     setContentView(R.layout.testsound); 

     mSensorManager = (SensorManager) getSystemService(Context.SENSOR_SERVICE); 
     mSensorListener = new ShakeEventListener(); 
     mSensorListener.setOnShakeListener(new ShakeEventListener.OnShakeListener() { 

      @Override 
      public void onShake() { 
      toggleSound(); 
      } 
     }); 
    } 

    @Override 
    protected void onResume() { 
     super.onResume(); 
     mSensorManager.registerListener(mSensorListener, 
      mSensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER), 
      SensorManager.SENSOR_DELAY_UI); 
    } 

    @Override 
    protected void onPause() { 
     super.onPause(); 
     mSensorManager.unregisterListener(mSensorListener); 
     stopSound(); 
    }  

    protected void toggleSound() { 
     if (!mIsPlaying) { 
      startSound(); 
     } else { 
      stopSound(); 
     } 
    } 


    protected void startSound() { 

     if (mPlayer == null) 
      { 
      mPlayer = MediaPlayer.create(TestActivity.this, R.raw.test); 
      mPlayer.setAudioStreamType(AudioManager.STREAM_MUSIC); 

      mPlayer.setLooping(true); 
      mPlayer.start(); 

      mPlayer.setOnCompletionListener(new OnCompletionListener() { 

       @Override 
       public void onCompletion(MediaPlayer mp) { 
        stopSound(); 
       } 
      }); 

      mIsPlaying = true; 
      } 
    } 


    protected void stopSound() { 
     if (mPlayer != null) { 
       if (mPlayer.isPlaying()) 
       { 
        mPlayer.stop(); 
       } 
       mPlayer.release(); 
       mPlayer = null; 
     } 

     mIsPlaying = false; 
    } 

} 

我知道這可能不是做的最好的方式，但我剛剛開始使用一些隨機測試。我沒有包含ShakeEventListener，但是這幾乎只是檢測一個搖動事件，在循環中播放一個示例聲音（是的，這非常煩人！），直到下一次搖晃。

事實上，這確實工作得很好，除非執行啓動和停止命令時獲得帶有標籤MediaPlayer的LogCat條目，該條目表示執行start() mUri is null或stop() mUri is null。這讓我相信我做錯了什麼，但是我無法找到它是什麼，當我谷歌一點時，這也不是一個流行的錯誤。

會有人知道這裏的含義嗎？對不起，如果我很厚 - 這對我來說仍然有點混亂。

更新（從評論）：我做的一件事是給它一個實際的Uri（從路徑建成），然後它帶有一個類似的警告，現在說start() mUri is android.resource://com.joris.soundtest/2130968576（D級）水平Uri is android.resource//...（點給相同的uri）。這些LogCat條目有可能只是'提供信息'，用於調試？ E級的人不會聽起來像這樣..

謝謝！ -Joris。

Answer 1

變化以後的事，因爲mediaplayer.release（）方法不會使MediaPlayer對象爲空...

package com.pranav.listviewdemo; 

import android.app.Activity; 
import android.content.Context; 
import android.hardware.Sensor; 
import android.hardware.SensorManager; 
import android.media.AudioManager; 
import android.media.MediaPlayer; 
import android.media.MediaPlayer.OnCompletionListener; 
import android.os.Bundle; 
import android.view.Window; 
import android.view.WindowManager; 
import android.widget.Toast; 

public class MainActivity extends Activity { 

    private SensorManager  mSensorManager; 
    private ShakeEventListener mSensorListener; 
    private MediaPlayer  mPlayer; 
    static int i=1; 

    private boolean   mIsPlaying=false; 

    /** Called when the activity is first created. */ 
    @Override 
    public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     requestWindowFeature(Window.FEATURE_NO_TITLE); 

     this.getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,WindowManager.LayoutParams.FLAG_FULLSCREEN); 

     setContentView(R.layout.activity_main); 

     mSensorManager = (SensorManager) getSystemService(Context.SENSOR_SERVICE); 
     mSensorListener = new ShakeEventListener(this,null); 
     mPlayer = MediaPlayer.create(this, R.raw.test); 
     mPlayer.setAudioStreamType(AudioManager.STREAM_MUSIC); 

     mPlayer.setLooping(true); 

     mPlayer.setOnCompletionListener(new OnCompletionListener() { 

      @Override 
      public void onCompletion(MediaPlayer mp) { 
       stopSound(); 
      } 
     }); 
     mSensorListener.setOnShakeListener(new ShakeEventListener.OnShakeListener() { 

      @Override 
      public void onShake() { 
      toggleSound(); 
      Toast.makeText(getBaseContext(), "DETECTED"+i, Toast.LENGTH_SHORT).show(); 
      i++; 
      } 
     }); 
    } 

    @Override 
    protected void onResume() { 
     super.onResume(); 
     mSensorManager.registerListener(mSensorListener, 
      mSensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER), 
      SensorManager.SENSOR_DELAY_UI); 
    } 

    @Override 
    protected void onPause() { 
     super.onPause(); 
     mSensorManager.unregisterListener(mSensorListener); 
     stopSound(); 
    }  

    protected void toggleSound() { 
     if (!mIsPlaying) { 
      startSound(); 
     } else { 
      stopSound(); 
     } 
    } 


    protected void startSound() { 

     if (mPlayer != null) 
      { 
      mPlayer.seekTo(0); 
      mPlayer.start(); 
      mIsPlaying = true; 
      } 
    } 


    protected void stopSound() { 
     if (mPlayer != null) { 
       if (mPlayer.isPlaying()) 
       { 
        mPlayer.pause(); 
        mIsPlaying = false; 
       } 

     } 


    } 

}