서비스의 생성자에서 Context.getPackageManager를 사용할 수없는 이유

Question

사용하려고하면 NullPointerException이 표시됩니다. 생성자 밖으로 이동하면 잘 동작합니다. 그래서, 나는 무슨 일이 일어나고 있는지 궁금해. 여기

코드입니다 :

package com.example.nullptrservice; 

import android.app.Service; 
import android.content.Intent; 
import android.content.pm.PackageManager; 
import android.os.IBinder; 
import android.util.Log; 

public class MyService extends Service { 
    public MyService() { 
     super(); 
     PackageManager pm = this.getPackageManager(); 
    } 

    @Override 
    public int onStartCommand(Intent intent, int flags, int startId){ 
     Log.i("MyService", "---------- started --------"); 
     return Service.START_NOT_STICKY; 
    } 

    @Override 
    public IBinder onBind(Intent intent) { return null; } 
} 

내가 수동으로 서비스를 실행할 때, 로그 캣 출력입니다 :

 
D/AndroidRuntime(4174): 
D/AndroidRuntime(4174): AndroidRuntime START com.android.internal.os.RuntimeInit 
D/AndroidRuntime(4174): CheckJNI is OFF 
D/AndroidRuntime(4174): Calling main entry com.android.commands.am.Am 
D/dalvikvm(4184): Late-enabling CheckJNI 
D/AndroidRuntime(4174): Shutting down VM 
I/ActivityManager( 148): Start proc com.example.nullptrservice for service com.example.nullptrservice/.MyService: pid=4184 uid=10066 gids={} 
I/AndroidRuntime(4174): NOTE: attach of thread 'Binder Thread #3' failed 
D/dalvikvm(4174): GC_CONCURRENT freed 103K, 81% free 489K/2560K, paused 1ms+1ms 
D/jdwp (4174): Got wake-up signal, bailing out of select 
D/dalvikvm(4174): Debugger has detached; object registry had 1 entries 
D/AndroidRuntime(4184): Shutting down VM 
W/dalvikvm(4184): threadid=1: thread exiting with uncaught exception (group=0x409ee1f8) 
E/AndroidRuntime(4184): FATAL EXCEPTION: main 
E/AndroidRuntime(4184): java.lang.RuntimeException: Unable to instantiate service com.example.nullptrservice.MyService: java.lang.NullPointerException 
E/AndroidRuntime(4184): at android.app.ActivityThread.handleCreateService(ActivityThread.java:2237) 
E/AndroidRuntime(4184): at android.app.ActivityThread.access$1600(ActivityThread.java:123) 
E/AndroidRuntime(4184): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1201) 
E/AndroidRuntime(4184): at android.os.Handler.dispatchMessage(Handler.java:99) 
E/AndroidRuntime(4184): at android.os.Looper.loop(Looper.java:137) 
E/AndroidRuntime(4184): at android.app.ActivityThread.main(ActivityThread.java:4424) 
E/AndroidRuntime(4184): at java.lang.reflect.Method.invokeNative(Native Method) 
E/AndroidRuntime(4184): at java.lang.reflect.Method.invoke(Method.java:511) 
E/AndroidRuntime(4184): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784) 
E/AndroidRuntime(4184): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551) 
E/AndroidRuntime(4184): at dalvik.system.NativeStart.main(Native Method) 
E/AndroidRuntime(4184): Caused by: java.lang.NullPointerException 
E/AndroidRuntime(4184): at android.content.ContextWrapper.getPackageManager(ContextWrapper.java:86) 
E/AndroidRuntime(4184): at com.example.nullptrservice.MyService.(MyService.java:12) 
E/AndroidRuntime(4184): at java.lang.Class.newInstanceImpl(Native Method) 
E/AndroidRuntime(4184): at java.lang.Class.newInstance(Class.java:1319) 
E/AndroidRuntime(4184): at android.app.ActivityThread.handleCreateService(ActivityThread.java:2234) 
E/AndroidRuntime(4184): ... 10 more 

안드로이드 4.0.3

또한 여기 related 질문 a bunch있다 on SO

Answer 1

012를 사용할 수 없습니다.(해당 문제의 경우 Activity)은 Context으로 개체가 생성/초기화 될 때 나타납니다.

대신에 onCreate()을 재정 의하여 거기에서 초기화를 수행하고 명시 적 생성자를 제거하십시오.

Answer 2

onCreate() 또는 서비스 생성자에서 처리기를 사용하여 처리기 내부에서 작업을 수행하십시오.