Java.lang.RuntimeException cannot create service instance: java.lang.NullPointerException

Question

I tried to create an action that starts the service (in a new thread). It consists of a layout with two editText and a submit button. The thing is, when I execute MainActivity, it throws this:

06-15 22:32:13.312: E/AndroidRuntime(643): FATAL EXCEPTION: main 06-15 22:32:13.312: E/AndroidRuntime(643): java.lang.RuntimeException: Unable to instantiate service hikoki.services.NotificationsService: java.lang.NullPointerException 06-15 22:32:13.312: E/AndroidRuntime(643): at android.app.ActivityThread.handleCreateService(ActivityThread.java:2237) 06-15 22:32:13.312: E/AndroidRuntime(643): at android.app.ActivityThread.access$1600(ActivityThread.java:123) 06-15 22:32:13.312: E/AndroidRuntime(643): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1201) 06-15 22:32:13.312: E/AndroidRuntime(643): at android.os.Handler.dispatchMessage(Handler.java:99) 06-15 22:32:13.312: E/AndroidRuntime(643): at android.os.Looper.loop(Looper.java:137) 06-15 22:32:13.312: E/AndroidRuntime(643): at android.app.ActivityThread.main(ActivityThread.java:4424) 06-15 22:32:13.312: E/AndroidRuntime(643): at java.lang.reflect.Method.invokeNative(Native Method) 06-15 22:32:13.312: E/AndroidRuntime(643): at java.lang.reflect.Method.invoke(Method.java:511) 06-15 22:32:13.312: E/AndroidRuntime(643): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784) 06-15 22:32:13.312: E/AndroidRuntime(643): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551) 06-15 22:32:13.312: E/AndroidRuntime(643): at dalvik.system.NativeStart.main(Native Method) 06-15 22:32:13.312: E/AndroidRuntime(643): Caused by: java.lang.NullPointerException 06-15 22:32:13.312: E/AndroidRuntime(643): at android.content.ContextWrapper.getSystemService(ContextWrapper.java:386) 06-15 22:32:13.312: E/AndroidRuntime(643): at hikoki.services.NotificationsService.<init>(NotificationsService.java:35) 06-15 22:32:13.312: E/AndroidRuntime(643): at java.lang.Class.newInstanceImpl(Native Method) 06-15 22:32:13.312: E/AndroidRuntime(643): at java.lang.Class.newInstance(Class.java:1319) 06-15 22:32:13.312: E/AndroidRuntime(643): at android.app.ActivityThread.handleCreateService(ActivityThread.java:2234) 06-15 22:32:13.312: E/AndroidRuntime(643): ... 10 more 

Main Operation Code:

 public class MainActivity extends Activity { private String TAG = getClass().getSimpleName(); @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); Thread t= new Thread(){ public void run(){ Intent intent=new Intent(getContext(),NotificationsService.class); //Intent intent=new Intent("hikoki.services.NotificationsService"); Log.d(TAG,"sending notificationsService"); startService(intent); } }; t.start(); } protected Context getContext() { return this; } } 

The od NotificationsService code is here:

 public class NotificationsService extends IntentService{ private static int TIME_INTERVAL_MILIS=5000; private static final int REFRESH=10; private NotificationManager noteManager; private static List<FlightStatusNote> flights= new ArrayList<FlightStatusNote>(); public NotificationsService(){ super("NotificationsService"); noteManager= NotificationManager)getSystemService(Context.NOTIFICATION_SERVICE) } } 

and AndroidManifest:

 <?xml version="1.0" encoding="utf-8"?> <manifest xmlns:android="http://schemas.android.com/apk/res/android" package="hikoki.services" android:versionCode="1" android:versionName="1.0" > <uses-sdk android:minSdkVersion="15" android:targetSdkVersion="17" /> <uses-permission android:name="android.permission.INTERNET" /> <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" /> <application android:allowBackup="true" android:icon="@drawable/ic_launcher" android:label="@string/app_name" android:theme="@style/AppTheme" > <activity android:name="hikoki.services.MainActivity" android:label="@string/app_name" > <intent-filter> <action android:name="android.intent.action.MAIN" /> <category android:name="android.intent.category.LAUNCHER" /> </intent-filter> </activity> <service android:name=".FlightStatusService"></service> <service android:enabled="true" android:name=".NotificationsService"></service> </application> </manifest> 

Answer 1

You cannot call getSystemService() from the initializer (as you originally were) or from the constructor (as you are now). Please override onCreate() and call getSystemService() there.

Basically, until onCreate() is called (or, more precisely, until you call super.onCreate() from your onCreate() ), the inherited methods on Service are not yet ready for your use.

Answer 2

I had the same error. My mistake was that the service did not have an empty default constructor. Here is the code that solved it:

 public class MyService extends IntentService { public MyService() { super(null); // That was the lacking constructor } public MyService(String name) { super(name); } //... }