我已经坚持了太长时间（昨天4个小时，今天3个小时！）现在。在我的主菜单屏幕中，我有一个静音按钮。我希望它在我的后台服务中调用一个方法，该方法将所有将在我的游戏背景中播放的MediaPlayer音频静音。
以下内容可能导致此问题：
每当音频播放（播放正常）时我都会收到错误：
QCMediaPlayer mediaplayer NOT present
E/MediaPlayer﹕ Should have subtitle controller already set
package com.example.USERNAME.buttonsmasher;
import android.app.Service;
import android.content.Context;
import android.content.Intent;
import android.media.MediaPlayer;
import android.os.CountDownTimer;
import android.os.IBinder;
import android.support.annotation.Nullable;
import android.util.Log;
public class TwentySeconds extends Service {
static MediaPlayer ten;
static MediaPlayer three;
final String TAG = "MyCountdown";
static CountDownTimer cdt;
double millisUntilFinishedRounded;
@Nullable
@Override
public IBinder onBind(Intent intent) {
return null;
}
@Override
public int onStartCommand(Intent intent, int flags, int startId) {
Context context = this;
three = MediaPlayer.create(TwentySeconds.this, R.raw.threetwoone);
ten = MediaPlayer.create(TwentySeconds.this, R.raw.tenmoreseconds);
// ten = MediaPlayer.create(TwentySeconds.this, R.raw.tenmoreseconds);
// three = MediaPlayer.create(TwentySeconds.this, R.raw.threetwoone);
Log.v(TAG, "In start command");
cdt = new CountDownTimer(20000, 1000) {
@Override
public void onTick(long millisUntilFinished) {
Log.v(TAG, millisUntilFinished + "left");
millisUntilFinishedRounded = (millisUntilFinished / 1000) * 1000;
if (millisUntilFinishedRounded == 10000) { //TEN SECONDS
// ten = MediaPlayer.create(TwentySeconds.this, R.raw.tenmoreseconds);
// while(ten == null){
ten = MediaPlayer.create(TwentySeconds.this, R.raw.tenmoreseconds);
// }
ten.start();
}
if (millisUntilFinishedRounded == 3000) {
/* Context context = this;
three = MediaPlayer.create(TwentySeconds.this, R.raw.threetwoone);
*/
// while(three == null){
three = MediaPlayer.create(TwentySeconds.this, R.raw.tenmoreseconds);
//}
three.start();
}
}
@Override
public void onFinish() {
Log.v(TAG, "Finished");
Intent intent = new Intent(TwentySeconds.this, GameOver.class);
intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
Log.v(TAG, "About to start activity");
startActivity(intent);
}
};
cdt.start();
return START_STICKY;
}
public static void stopTimer() {
cdt.cancel();
}
public static void myMute() {
ten.setVolume(0, 0);
three.setVolume(0, 0);
}
public static void unMute() {
ten.setVolume(1, 1);
three.setVolume(1, 1);
}
@Override
public void onDestroy() {
stopSelf();
super.onDestroy();
}
}
_______________________________________________________________________________________________________________________________
Here is the method in Main_Menu (x starts as zero)
if ((x%2) == 0) { //If it's even
TwentySeconds.unMute();
Toast.makeText(Main_Menu.this, "UNMUTED", Toast.LENGTH_SHORT).show();
x++;
} else { //If its odd
TwentySeconds.myMute();
Toast.makeText(Main_Menu.this, "MUTED", Toast.LENGTH_SHORT).show();
x++;
}
__________________________________________________________________
这是堆栈跟踪：
java.lang.IllegalStateException: Could not execute method of the activity
at android.view.View$1.onClick(View.java:3842)
at android.view.View.performClick(View.java:4457)
at android.view.View$PerformClick.run(View.java:18491)
at android.os.Handler.handleCallback(Handler.java:733)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5272)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:883)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:699)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.reflect.InvocationTargetException
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at android.view.View$1.onClick(View.java:3837)
at android.view.View.performClick(View.java:4457)
at android.view.View$PerformClick.run(View.java:18491)
at android.os.Handler.handleCallback(Handler.java:733)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5272)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:883)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:699)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException
at com.example.USERNAME.buttonsmasher.TwentySeconds.myMute(TwentySeconds.java:106)
at com.example.USERNAME.buttonsmasher.Main_Menu.mute(Main_Menu.java:103)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at android.view.View$1.onClick(View.java:3837)
at android.view.View.performClick(View.java:4457)
at android.view.View$PerformClick.run(View.java:18491)
at android.os.Handler.handleCallback(Handler.java:733)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5272)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:883)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:699)
at dalvik.system.NativeStart.main(Native Method)
我真的很感激任何反馈（积极或消极）！ 需要帮助请叫我。非常感谢所有事情，我希望我能解决这个问题... :)