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NullPointerException: if (cursor.moveToFirst()) { - Java / Android Application for University

 
UniversityOfTxtech Students
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My classmates and I have an issue with a project we are building.

We've successfully built an Android app which contains an activity which searches our browser histories / bookmarks for specific urls and launches another activity (successfully) if a match is found as an example of an adult content warning implementation.

This is functioning fine.


Now we are implementing a service class to continually execute every few seconds - in order to execute the search of our recent history using our new service class - but we're experiencing a few issues.


Our problem is when we attempt to add the "Nanny" source code from Nanny.java to the service class so the "Nanny" script will search the history continuously, instead of just once - the "Nanny" application continually force closes - due to a null pointer exception at the initialization of our cursor: `if (cursor.moveToFirst()) {`

Which is a bit strange because the NullPointerException does not occur when the exact same script is executed outside the service class in a test file we have (Main.java)


Our working Main.java and our working service class [which successfully displays a toast every few seconds] as well as our [failed] combination of the two - are shown below:




Empty Service Class:

Working Nanny.java


Unsuccessful method we've attempted to implement (adding the functioning nanny script to the service class) which causes the NullPointerException: if (cursor.moveToFirst()) {





LOGCAT (When using combined implementation shown above)


Fails on Line 53: if (cursor.moveToFirst()) {



04-15 18:26:24.761: D/dalvikvm(7466): Late-enabling CheckJNI
04-15 18:26:25.651: D/dalvikvm(7466): GC_FOR_ALLOC freed 82K, 4% free 7379K/7608K, paused 13ms, total 13ms
04-15 18:26:25.651: I/dalvikvm-heap(7466): Grow heap (frag case) to 10.861MB for 3686416-byte allocation
04-15 18:26:25.661: D/dalvikvm(7466): GC_FOR_ALLOC freed 1K, 3% free 10977K/11212K, paused 13ms, total 13ms
04-15 18:26:25.681: D/dalvikvm(7466): GC_CONCURRENT freed <1K, 3% free 10977K/11212K, paused 3ms+2ms, total 17ms
04-15 18:26:25.901: D/dalvikvm(7466): GC_FOR_ALLOC freed <1K, 3% free 10977K/11212K, paused 11ms, total 11ms
04-15 18:26:25.911: I/dalvikvm-heap(7466): Grow heap (frag case) to 17.086MB for 6529744-byte allocation
04-15 18:26:25.931: D/dalvikvm(7466): GC_FOR_ALLOC freed 0K, 2% free 17354K/17592K, paused 13ms, total 13ms
04-15 18:26:25.941: D/dalvikvm(7466): GC_CONCURRENT freed <1K, 2% free 17354K/17592K, paused 3ms+2ms, total 16ms
04-15 18:26:26.051: D/libEGL(7466): loaded /system/lib/egl/libEGL_tegra.so
04-15 18:26:26.061: D/libEGL(7466): loaded /system/lib/egl/libGLESv1_CM_tegra.so
04-15 18:26:26.071: D/libEGL(7466): loaded /system/lib/egl/libGLESv2_tegra.so
04-15 18:26:26.091: D/OpenGLRenderer(7466): Enabling debug mode 0
04-15 18:26:31.181: D/AndroidRuntime(7466): Shutting down VM
04-15 18:26:31.181: W/dalvikvm(7466): threadid=1: thread exiting with uncaught exception (group=0x40f4f930)
04-15 18:26:31.181: E/AndroidRuntime(7466): FATAL EXCEPTION: main
04-15 18:26:31.181: E/AndroidRuntime(7466): java.lang.RuntimeException: Unable to start service com.ut.appdemo.Service_class@41698e90 with Intent { cmp=com.ut.appdemo/.Service_class }: java.lang.NullPointerException
04-15 18:26:31.181: E/AndroidRuntime(7466): at android.app.ActivityThread.handleServiceArgs(ActivityThread.java:2673)
04-15 18:26:31.181: E/AndroidRuntime(7466): at android.app.ActivityThread.access$1900(ActivityThread.java:141)
04-15 18:26:31.181: E/AndroidRuntime(7466): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1331)
04-15 18:26:31.181: E/AndroidRuntime(7466): at android.os.Handler.dispatchMessage(Handler.java:99)
04-15 18:26:31.181: E/AndroidRuntime(7466): at android.os.Looper.loop(Looper.java:137)
04-15 18:26:31.181: E/AndroidRuntime(7466): at android.app.ActivityThread.main(ActivityThread.java:5041)
04-15 18:26:31.181: E/AndroidRuntime(7466): at java.lang.reflect.Method.invokeNative(Native Method)
04-15 18:26:31.181: E/AndroidRuntime(7466): at java.lang.reflect.Method.invoke(Method.java:511)
04-15 18:26:31.181: E/AndroidRuntime(7466): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
04-15 18:26:31.181: E/AndroidRuntime(7466): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
04-15 18:26:31.181: E/AndroidRuntime(7466): at dalvik.system.NativeStart.main(Native Method)
04-15 18:26:31.181: E/AndroidRuntime(7466): Caused by: java.lang.NullPointerException
04-15 18:26:31.181: E/AndroidRuntime(7466): at com.ut.appdemo.Service_class.onStartCommand(Service_class.java:53)
04-15 18:26:31.181: E/AndroidRuntime(7466): at android.app.ActivityThread.handleServiceArgs(ActivityThread.java:2656)
04-15 18:26:31.181: E/AndroidRuntime(7466): ... 10 more
 
Steve Luke
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1) Where do you get the cursor fom?

2) What does that method return (always)?
 
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