MediaPlayer.prepare()

Java code

    ......    mMediaPlayer = new MediaPlayer();    initialMediaPlayerData();    ......private void initialMediaPlayerData() {        Log.e(TAG, "initialMediaPlayerData");        try {            Log.d(MYTAG,"mMediaPlayer  prepare !");            mMediaPlayer.setDataSource(parentContext, mSelectedUri);            mMediaPlayer.setOnCompletionListener(listener);            mMediaPlayer.setAudioStreamType(AudioManager.STREAM_MUSIC);            mMediaPlayer.prepare();        }         catch (IOException e)         {            Log.e("MusicPicker", "Unable to play track", e);        }    }

以上的代码在我的一个APK中，现在发现一个奇怪的问题：
在AP第一次运行的时候，一切正常。
按back建关闭AP以后，再次启动AP的时候，运行到mMediaPlayer.prepare()函数的时候，发生IllegalStateException异常，求解释～

[解决办法]
mMediaPlayer并没有关闭。。。。。
[解决办法]
When a MediaPlayer object is just created using new or after reset() is called, it is in the Idle state; and after release() is called, it is in the End state. Between these two states is the life cycle of the MediaPlayer object.