public int getCount(Uri uri){
Cursor c=null;
int size=0;
if(uri.equals(DatabaseContants.CONTENT_URI_SETTING)){
c=mContentResolver.query(uri,
DatabaseContants.COLUMNS_SETTING,null, null,null);
}
else if(uri.equals(DatabaseContants.CONTENT_URI_FAVORITEPOI)){
Log.v(TAG,"ContentResolver is "+mContentResolver);
c=mContentResolver.query(uri,
DatabaseContants.COLUMNS_FAVORITEPOI,null,
null,DatabaseContants.PLACEID_FAVORITE+" DESC");
Log.v(TAG,"Cursor c is "+c);
}
if(c!=null&&c.getCount()>0)size=c.getCount();
c.close();
return size;
}
the error appears in this function.
在 2012年12月12日星期三UTC+8上午11时13分55秒，Hilda Chen写道：
>
> Hi All:
> I create a datatbase with provider and get the data by content
> resolver. when call ContentResolver.insert is ok, but
> ContentResolver.query fail.
> c=mContentResolver.query(uri,
> DatabaseContants.COLUMNS_FAVORITEPOI,null,
> null,DatabaseContants.PLACEID_FAVORITE+" DESC");
> it return null, and the ContentResolver is not null;
> the log is
> 06-02 03:31:34.235: E/AndroidRuntime(23134): FATAL EXCEPTION: main
> 06-02 03:31:34.235: E/AndroidRuntime(23134): java.lang.RuntimeException:
> Unable to start activity
> ComponentInfo{com.example.providerdatabase/com.example.providerdatabase.PrivoterDatabaseActivity}:
>
> java.lang.NullPointerException
> 06-02 03:31:34.235: E/AndroidRuntime(23134): at
> android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2082)
> 06-02 03:31:34.235: E/AndroidRuntime(23134): at
> android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2107)
> 06-02 03:31:34.235: E/AndroidRuntime(23134): at
> android.app.ActivityThread.access$600(ActivityThread.java:139)
> 06-02 03:31:34.235: E/AndroidRuntime(23134): at
> android.app.ActivityThread$H.handleMessage(ActivityThread.java:1207)
> 06-02 03:31:34.235: E/AndroidRuntime(23134): at
> android.os.Handler.dispatchMessage(Handler.java:99)
> 06-02 03:31:34.235: E/AndroidRuntime(23134): at
> android.os.Looper.loop(Looper.java:137)
> 06-02 03:31:34.235: E/AndroidRuntime(23134): at
> android.app.ActivityThread.main(ActivityThread.java:4812)
> 06-02 03:31:34.235: E/AndroidRuntime(23134): at
> java.lang.reflect.Method.invokeNative(Native Method)
> 06-02 03:31:34.235: E/AndroidRuntime(23134): at
> java.lang.reflect.Method.invoke(Method.java:511)
> 06-02 03:31:34.235: E/AndroidRuntime(23134): at
> com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:789)
> 06-02 03:31:34.235: E/AndroidRuntime(23134): at
> com.android.internal.os.ZygoteInit.main(ZygoteInit.java:556)
> 06-02 03:31:34.235: E/AndroidRuntime(23134): at
> dalvik.system.NativeStart.main(Native Method)
> 06-02 03:31:34.235: E/AndroidRuntime(23134): Caused by:
> java.lang.NullPointerException
> 06-02 03:31:34.235: E/AndroidRuntime(23134): at
> com.example.providerdatabase.DatabaseController.getCount(DatabaseController.java:47)
> 06-02 03:31:34.235: E/AndroidRuntime(23134): at
> com.example.providerdatabase.PrivoterDatabaseActivity.onCreate(PrivoterDatabaseActivity.java:62)
> 06-02 03:31:34.235: E/AndroidRuntime(23134): at
> android.app.Activity.performCreate(Activity.java:5008)
> 06-02 03:31:34.235: E/AndroidRuntime(23134): at
> android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1079)
> 06-02 03:31:34.235: E/AndroidRuntime(23134): at
> android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2046)
> 06-02 03:31:34.235: E/AndroidRuntime(23134): ... 11 more
>
> can you help me?
> Thanks!
> Hilda
>
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