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我有一個彈出窗口（非活動類），它具有一些按鈕。其中一個（btn_audio），播放或暫停聲音，它的作用就像一個魅力。
現在我想在我的HomeActivity中調用兩種方法，play()和pause()，並在我的所有Activities中調用onStop()方法。它不起作用，請致電play()和pause()在其他Activity中發生NullPointException。Android中非活動類的調用方法
public class Popup_Menu extends Activity implements OnClickListener {
Button btn_audio;
public static MediaPlayer player; String play_or_pause;
int num_ply, tim_pos; int [] resID;// Audio
SharedPreferences sp;
void showPopup(final Activity context) {
this.context=context;
LinearLayout viewGroup = (LinearLayout) context.findViewById(R.id.popup);
LayoutInflater layoutInflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
layout = layoutInflater.inflate(R.layout.popup_layout_menu, viewGroup);
sp = context.getSharedPreferences("text", MODE_PRIVATE);
btn_audio = (Button) layout.findViewById(R.id.btn_audio); // audio
layout.findViewById(R.id.btn_audio).setOnClickListener(this);
@Override
public void onClick(View whichButtonIsClicked) {
switch (whichButtonIsClicked.getId()) {
case R.id.btn_audio:
if (play_or_pause.equals("play")) {
pause();
} else {
play(context);
}
sp.edit().putString("play_or_pause", play_or_pause).commit(); // save current stat
} ////// close of showPopup()
//define play and pause methods
public void pause() {
player.pause();
btn_audio.setBackgroundResource(R.drawable.icon_audio_pause);
play_or_pause="pause"; // current state is 'pause'
}
public void play(final Context context) {
if(num_ply==9){num_ply=0; }
resID = new int []{ R.raw.tarane,R.raw.toofan,R.raw.shane,R.raw.kharazmi,R.raw.golhaye_khofte,R.raw.rang,R.raw.naghmeh,R.raw.dar_rahe_to,R.raw.emperor};
player=MediaPlayer.create(context,resID[num_ply]);
player.seekTo(tim_pos);
player.start();
btn_audio.setBackgroundResource(R.drawable.icon_audio_play);
play_or_pause="play"; // current state is 'play'
player.setOnCompletionListener(new OnCompletionListener() {
public void onCompletion(MediaPlayer player) {
tim_pos=0; num_ply++; play(context);
}
});
}
}
和我HomeActivity：
public class HomeActivity extends Activity implements OnClickListener {
Popup_Menu ppp;
@Override
protected void onCreate..............
ppp = new Popup_Menu();
SharedPreferences sp = getSharedPreferences("text", MODE_PRIVATE);
if(sp.getString("play_or_pause", "play").equals("pause")){
ppp.play(getApplicationContext()); // ERROR
} // audio
} /// close of onCreate
@Override
public void onStop() {
super.onStop();
if(play_or_pause.equals("play")){
ppp.tim_pos= ppp.player.getCurrentP
好吧，我決定用服務來解決這個問題，它可以很好地用於播放（）。但是在播放時，仍然無法從SoundService調用pause（）方法，因爲player對象爲null。我認爲通過從SoundService類創建一個對象（SS在Popup_Menu類中），默認構造函數將播放器值設置爲null（當播放和播放器對象不爲null時）。並調用player.pause發生錯誤。 如何請我暫停此one_week_friend !!!
public class SoundService extends Service {
MediaPlayer player; int num_ply, tim_pos; int [] resID;
public int onStartCommand(Intent intent, int flags, int startId) {
resID = new int []{ R.raw.tarane,R.raw.toofan,R.raw.shane,R.raw.kharazmi,
R.raw.golhaye_khofte,R.raw.rang,R.raw.naghmeh,R.raw.dar_rahe_to,R.raw.emperor };
player=MediaPlayer.create(this,resID[num_ply]);
play();
return Service.START_FLAG_REDELIVERY;
}
public void play() {
if(num_ply==9){num_ply=0; }
player.seekTo(tim_pos);
player.start();
player.setOnCompletionListener(new OnCompletionListener() {
public void onCompletion(MediaPlayer player) {
tim_pos=0; num_ply++; play();
}
});
}
public void resume(){
player.seekTo(tim_pos);
player.start();
}
public void pause() {
tim_pos= player.getCurrentPosition(); ////// ERROR
player.pause(); ////// ERROR
num_ply++;
}
public IBinder onBind(Intent arg0) {
// TODO Auto-generated method stub
return null;
}
}
而且我Popup_Menu類：
@Override
public void onClick(View whichButtonIsClicked) {
switch (whichButtonIsClicked.getId()) {
case R.id.btn_audio:
if (play_or_pause.equals("play")) {
btn_audio.setBackgroundResource(R.drawable.icon_audio_pause);
play_or_pause="pause"; // current state is 'pause'
SoundService ss = new SoundService();
ss.pause(); ////// ERROR
} else {
btn_audio.setBackgroundResource(R.drawable.icon_audio_play);
play_or_pause="play"; // current state is 'play'
Intent sound_Intent = new Intent(context , SoundService.class); // start service
context.startService(sound_Intent);
}
sp.edit().putString("play_or_pause", play_or_pause).commit(); // save current state
break;
的logcat：
08-05 01:03:31.440: E/AndroidRuntime(25356): FATAL EXCEPTION: main
08-05 01:03:31.440: E/AndroidRuntime(25356): java.lang.NullPointerException
08-05 01:03:31.440: E/AndroidRuntime(25356): at com.codegostarNiloo.negar.SoundService.pause(SoundService.java:47)
08-05 01:03:31.440: E/AndroidRuntime(25356): at com.codegostarNiloo.negar.Popup_Menu.onClick(Popup_Menu.java:234)
08-05 01:03:31.440: E/AndroidRuntime(25356): at android.view.View.performClick(View.java:4209)
08-05 01:03:31.440: E/AndroidRuntime(25356): at android.view.View$PerformClick.run(View.java:17457)
08-05 01:03:31.440: E/AndroidRuntime(25356): at android.os.Handler.handleCallback(Handler.java:725)
08-05 01:03:31.440: E/AndroidRuntime(25356): at android.os.Handler.dispatchMessage(Handler.java:92)
08-05 01:03:31.440: E/AndroidRuntime(25356): at android.os.Looper.loop(Looper.java:153)
08-05 01:03:31.440: E/AndroidRuntime(25356): at android.app.ActivityThread.main(ActivityThread.java:5341)
08-05 01:03:31.440: E/AndroidRuntime(25356): at java.lang.reflect.Method.invokeNative(Native Method)
08-05 01:03:31.440: E/AndroidRuntime(25356): at java.lang.reflect.Method.invoke(Method.java:511)
08-05 01:03:31.440: E/AndroidRuntime(25356): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:929)
08-05 01:03:31.440: E/AndroidRuntime(25356): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:696)
08-05 01:03:31.440: E/AndroidRuntime(25356): at dalvik.system.NativeStart.main(Native Method)
08-05 01:03:32.066: D/dalvikvm(25356): threadid=11: interp stack at 0x5f1c9000
你能包括你的堆棧跟蹤嗎？ – cjnash
請縮進代碼，很難閱讀 – litelite
發佈您的logcat消息 –