从服务启动活动

Question

When I am trying to launch a call activity from a Service, I get a NullPointerException . Here is my code:

Intent callIntent = new Intent(Intent.ACTION_CALL);
callIntent.setData(Uri.parse("tel:" + number));
callIntent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
startActivity(callIntent);

I get the exception on the startActivity line.

I tried to use getApplication.startActivity and getApplicationContext.startActivity but no luck.

Any ideas?

edit : Maybe some usefull info: I am trying to create a service that will run on the background and scan sensor data, when a certain signal is given i would like to maken an automated call to a number.

edit : full adb error code:

03-31 09:04:10.214: ERROR/AndroidRuntime(1896): Uncaught handler: thread main exiting due to uncaught exception
03-31 09:04:10.226: ERROR/AndroidRuntime(1896): java.lang.RuntimeException: Unable to instantiate service dfz.epilepsiedetector.services.DetectionService: java.lang.NullPointerException
03-31 09:04:10.226: ERROR/AndroidRuntime(1896):     at android.app.ActivityThread.handleCreateService(ActivityThread.java:2668)
03-31 09:04:10.226: ERROR/AndroidRuntime(1896):     at android.app.ActivityThread.access$3100(ActivityThread.java:116)
03-31 09:04:10.226: ERROR/AndroidRuntime(1896):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1846)
03-31 09:04:10.226: ERROR/AndroidRuntime(1896):     at android.os.Handler.dispatchMessage(Handler.java:99)
03-31 09:04:10.226: ERROR/AndroidRuntime(1896):     at android.os.Looper.loop(Looper.java:123)
03-31 09:04:10.226: ERROR/AndroidRuntime(1896):     at android.app.ActivityThread.main(ActivityThread.java:4203)
03-31 09:04:10.226: ERROR/AndroidRuntime(1896):     at java.lang.reflect.Method.invokeNative(Native Method)
03-31 09:04:10.226: ERROR/AndroidRuntime(1896):     at java.lang.reflect.Method.invoke(Method.java:521)
03-31 09:04:10.226: ERROR/AndroidRuntime(1896):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:791)
03-31 09:04:10.226: ERROR/AndroidRuntime(1896):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:549)
03-31 09:04:10.226: ERROR/AndroidRuntime(1896):     at dalvik.system.NativeStart.main(Native Method)
03-31 09:04:10.226: ERROR/AndroidRuntime(1896): Caused by: java.lang.NullPointerException
03-31 09:04:10.226: ERROR/AndroidRuntime(1896):     at android.content.ContextWrapper.getPackageName(ContextWrapper.java:120)
03-31 09:04:10.226: ERROR/AndroidRuntime(1896):     at android.content.ComponentName.<init>(ComponentName.java:75)
03-31 09:04:10.226: ERROR/AndroidRuntime(1896):     at android.content.Intent.<init>(Intent.java:2302)
03-31 09:04:10.226: ERROR/AndroidRuntime(1896):     at dfz.epilepsiedetector.services.DetectionService.<init>(DetectionService.java:35)
03-31 09:04:10.226: ERROR/AndroidRuntime(1896):     at java.lang.Class.newInstanceImpl(Native Method)
03-31 09:04:10.226: ERROR/AndroidRuntime(1896):     at java.lang.Class.newInstance(Class.java:1472)
03-31 09:04:10.226: ERROR/AndroidRuntime(1896):     at android.app.ActivityThread.handleCreateService(ActivityThread.java:2665)

edit Trimmed class code:

public class DetectionService extends IntentService implements SensorEventListener
{   
 private SensorManager mSensorManager;
 private Sensor mAccelerometer;
 private boolean hasSeizure = false;

 private final int POLLS_PER_SECOND = 10;

 public DetectionService()
 {
 super("EpilepsionDetectionService");

 Intent callIntent = new Intent(DetectionService.this,
 InformationActivity.class);
 callIntent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);        
 getApplication().startActivity(callIntent);
}

Answer 1

You have to get that context from an activity where you calling a service.. from that you have to call`

Intent callIntent = new Intent(Intent.ACTION_CALL);
callIntent.setData(Uri.parse("tel:" + number));


 callIntent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
 context.startActivity(callIntent);

edit :

callIntent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
getApplication().startActivity(callIntent);`

`

hope it helps...

Answer 2

You can try:

getBaseContext().startActivity(callIntent);

Or use:

this.startActivity(callIntent);

Answer 3

For future reference:

The problem went away when inhereting directly from Service as opposed to Intent service.

Hop this helps!

Answer 4

Move the code out of the constructor and into the onCreate() method. The long and short of it is that the class hasn't been totally initialized yet and is causing the NullPointerException .

Answer 5

在服务的onStart方法而不是onCreate方法中调用意图。