我有自定义媒体服务和音频播放器类，它与之通信但未绑定到服务。
当我创建MyService的对象并编写代码时： -
myService.player.getDuration()中的onCreate我在此行上获得空指针异常。
但如果我在同一个屏幕上点击某个按钮监听器来编写此代码，那么我会得到确切的持续时间。
我已经尝试了所有可能的语法来解决这个问题，但仍然无法解决问题。
**我的服务代码是： - **
private static final String TAG = "MyService";
public static MediaPlayer player;
String song_uri,url;
Bundle b;
private IBinder myBinder;
private boolean isplaying;
public static final String Song_uri="song_uri";
public static final String EXTRA_SHUFFLE="EXTRA_SHUFFLE";
@Override
public IBinder onBind(Intent intent) {
return null;
}
public class MyBinder extends Binder{
MyService getService()
{
return MyService.this;
}
}
@Override
public void onCreate() {
Log.d(TAG, "onCreate "+song_uri);
}
@Override
public void onDestroy() {
//Toast.makeText(this, "My Service Stopped", Toast.LENGTH_LONG).show();
DataManager.getInstance().setWantsToPlaySong(false);
DataManager.getInstance().setCurrentPosition(0);
Log.d(TAG, "onDestroy");
player.stop();
//player.release();
}
public void onPause()
{
player.pause();
}
public double duration()
{
return player.getDuration();
}
public void onStart(Intent intent, int startid) {
DataManager.getInstance().setWantsToPlaySong(true);
Bundle b=intent.getExtras();
song_uri=b.getString("song_uri");
Uri path=Uri.parse(song_uri);
player = MediaPlayer.create(this,path );
player.setLooping(false); // Set looping
//Toast.makeText(this, "My Service Started"+" Duration = "+(player.getDuration()/1000)/60, Toast.LENGTH_SHORT).show();
Log.d(TAG, "onStart"+song_uri);
player.start();
}
音频播放器的代码是： -
uri = this.getIntent().getExtras().getString("song_uri");
buttonStart = (Button) findViewById(R.id.buttonStart);
buttonStop = (Button) findViewById(R.id.buttonStop);
buttonPause = (Button) findViewById(R.id.buttonPause);
tracks = dbManager.getAllSongs(AudioPlayer2.this);
buttonForward = (Button) findViewById(R.id.buttonforward);
buttonBackward = (Button) findViewById(R.id.buttonbackward);
//=========================================================================================
sArtworkUri = Uri.parse("content://media/external/audio/albumart");
//myservice=new MyService();
Uri path = Uri.parse(uri);
current_song=this.getIntent().getExtras().getInt("current_song");
albumArtUri = this.getIntent().getExtras().getString("album_art");
Uri sArtworkUri = Uri.parse("content://media/external/audio/albumart");
album_id = Long.parseLong(this.getIntent().getStringExtra("album_id"));
int id = Integer.parseInt(this.getIntent().getStringExtra("album_id"));
albumImageUri = ContentUris.withAppendedId(sArtworkUri, album_id);
ivAlbumArt = (ImageView) findViewById(R.id.album_art);
songName = this.getIntent().getStringExtra("song_name");
albumName = this.getIntent().getStringExtra("album_name");
tvName = (TextView) findViewById(R.id.tv_name);
tvAlbum = (TextView) findViewById(R.id.tv_album);
if (songName != null) {
tvName.setText(songName);
}
if (albumName != null) {
tvAlbum.setText(albumName);
}
// buttonStart.performClick();
if (DataManager.getInstance().getOnPausedSong()=="y"){
//Toast.makeText(AudioPlayer2.this, "stage 1", Toast.LENGTH_SHORT).show();
if(DataManager.getInstance().getPausedSongName()==songName){
//Toast.makeText(AudioPlayer2.this, "stage 1", Toast.LENGTH_SHORT).show();
buttonStart.setVisibility(View.GONE);
buttonPause.setVisibility(View.VISIBLE);
}
}
FetchImage fetchImage = new FetchImage();
fetchImage.execute();
/*if(DataManager.getInstance().getSong_uri()!=null)
{
stopService(new Intent(this, MyService.class));
}*/
// if(myService.player.isPlaying())
//{
stopService(new Intent(this, MyService.class));
Intent intent = new Intent(this,MyService.class);
Bundle b = new Bundle();
b.putString("song_uri",uri );
intent.putExtras(b);
startService(intent);
myService.player.setOnCompletionListener(new OnCompletionListener() {
@Override
public void onCompletion(MediaPlayer mp) {
// TODO Auto-generated method stub
buttonStart.setVisibility(View.VISIBLE);
buttonPause.setVisibility(View.GONE);
}
});
buttonStart.setVisibility(View.GONE);
buttonPause.setVisibility(View.VISIBLE);
// Toast.makeText(this, "Duration: "+myService.player.getDuration(), Toast.LENGTH_LONG).show();
/*//}//DataManager.getInstance().setSong_uri(uri);
Intent intent = new Intent(this,MyService.class);
Bundle b = new Bundle();
b.putString("song_uri",uri );
intent.putExtras(b);
startService(intent);
buttonStart.setVisibility(View.GONE);
buttonPause.setVisibility(View.VISIBLE);
DataManager.getInstance().setSong_uri(uri);
DataManager.getInstance().setOnPausedSong("y");
DataManager.getInstance().setPausedSongName(songName);
*/ //buttonStart.setPressed(true);
//=======================================================================================
buttonStart.setOnClickListener(this);
buttonPause.setOnClickListener(this);
buttonForward.setOnClickListener(this);
buttonBackward.setOnClickListener(this);
buttonStop.setOnClickListener(this);
// buttonPause.performClick();
/* new Thread(myThread).start();
*/ }
// Thread for seekbar
// song starts playing
public void onClick(View src) {
switch (src.getId()) {
case R.id.buttonStart:
if(DataManager.getInstance().getSongPause()=="y"){
myService.player.start();
DataManager.getInstance().setSongPause("n");
buttonStart.setVisibility(View.GONE);
buttonPause.setVisibility(View.VISIBLE);
// DataManager.getInstance().setWantsToPlaySong(true);
//DataManager.getInstance().setOnPausedSong("n");
//DataManager.getInstance().setOnPausedSong("y");
}else{
stopService(new Intent(this, MyService.class));
DataManager.getInstance().setSong_uri(uri);
Intent intent = new Intent(this,MyService.class);
Bundle b = new Bundle();
b.putString("song_uri",uri );
intent.putExtras(b);
startService(intent);
buttonStart.setVisibility(View.GONE);
buttonPause.setVisibility(View.VISIBLE);
DataManager.getInstance().setOnPausedSong("y");
DataManager.getInstance().setPausedSongName(songName);
}
//Toast.makeText(this, "My Service Started", Toast.LENGTH_LONG).show();
break;
case R.id.buttonStop:
Log.d(TAG, "onClick: stopping srvice");
stopService(new Intent(this, MyService.class));
buttonStart.setVisibility(View.VISIBLE);
buttonPause.setVisibility(View.GONE);
break;
case R.id.buttonforward:
stopService(new Intent(this, MyService.class));
current_song++;
FetchAllMusic fetchAllMusic = new FetchAllMusic();
fetchAllMusic.execute();
//new Thread(myThread).start();
break;
case R.id.buttonbackward:
Log.d(TAG, "onClick: stopping service");
stopService(new Intent(this, MyService.class));
if(current_song>0){
current_song--;
}
FetchAllMusic fetchAllMusic2 = new FetchAllMusic();
fetchAllMusic2.execute();
break;
case R.id.buttonPause:
buttonStart.setVisibility(View.VISIBLE);
buttonPause.setVisibility(View.GONE);
/* MyService myservice=new MyService();
myservice.onPause();*/
myService.player.pause();
DataManager.getInstance().setSongPause("y");
DataManager.getInstance().setWantsToPlaySong(false);
DataManager.getInstance().setOnPausedSong("n");
DataManager.getInstance().setPausedSongName(songName);
//duration=myService.player.getDuration();
// Toast.makeText(this, ""+duration, Toast.LENGTH_LONG).show();
}
}
public void onBackPressed() {
try {
//addvideo.removeView(DBManager.getInstance().getVideo());
DataManager.getInstance().setSong_uri(uri);
DataManager.getInstance().setAlbum_id(""+album_id);
DataManager.getInstance().setAlbumName(albumName);
DataManager.getInstance().setSongName(songName);
DataManager.getInstance().setAlbumArtUri(albumArtUri);
DataManager.getInstance().setCurrent_song(current_song);
DataManager.getInstance().setWantsToPlaySong(false);
} catch (Exception e) {
e.printStackTrace();
}
super.onBackPressed();
}
private Runnable myThread = new Runnable(){
@Override
public void run() {
Log.d(TAG, "Thread Starts");
// TODO Auto-generated method stub
while (myProgress<100){
try{
Log.d(TAG, "Thread Starts");
myHandle.sendMessage(myHandle.obtainMessage());
Thread.sleep(3000);
}
catch(Throwable t){
}
}
}
Handler myHandle = new Handler(){
public void handleMessage(Message msg) {
// TODO Auto-generated method stub
myProgress++;
seekbar.setProgress(myProgress);
}
};
};
答案 0 :(得分：2)
这不是语法问题;这是一个变量初始化问题。当该行在myService中执行时，myService.player或null为onCreate()。检查代码中的初始化位置，并确保在设置之前不要引用它们。