ManagedQuery causing nullpointerexception

Question

I am working on a project and want to read call logs and write them to file and send it to server. My code for reading call logs in working fine in a separate project. But it causes NullPointerException when integrates code with original project. All permissions are verified. here is my code

BufferedWriter buf = new BufferedWriter(new FileWriter(logFile, true)); 
              buf.append("Testing ");
              buf.newLine();
                sb = new StringBuffer();
                Uri str = CallLog.Calls.CONTENT_URI;
                str.toString();
                Log.e("TAG", str.toString());


                  @SuppressWarnings("deprecation")
            Cursor managedCursor =managedQuery(CallLog.Calls.CONTENT_URI, null,
                            null, null, null);
                Log.e("TAG", "in while " + ++i);
              int number = managedCursor.getColumnIndex(CallLog.Calls.NUMBER);
                int type = managedCursor.getColumnIndex(CallLog.Calls.TYPE);
                int date = managedCursor.getColumnIndex(CallLog.Calls.DATE);
                int duration = managedCursor.getColumnIndex(CallLog.Calls.DURATION);
                sb.append("Call Details :");

Logcat shows this error 05-15 16:17:14.107: E/AndroidRuntime(20715): FATAL EXCEPTION: main 05-15 16:17:14.107: E/AndroidRuntime(20715): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.atu_proto/com.example.atu_proto.MenuList}: java.lang.NullPointerException

05-15 16:17:14.107: E/AndroidRuntime(20715): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2313)

05-15 16:17:14.107: E/AndroidRuntime(20715): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2365)

05-15 16:17:14.107: E/AndroidRuntime(20715): at android.app.ActivityThread.access$600(ActivityThread.java:156)

05-15 16:17:14.107: E/AndroidRuntime(20715): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)

05-15 16:17:14.107: E/AndroidRuntime(20715): at android.os.Handler.dispatchMessage(Handler.java:99)

05-15 16:17:14.107: E/AndroidRuntime(20715): at android.os.Looper.loop(Looper.java:153)

05-15 16:17:14.107: E/AndroidRuntime(20715): at android.app.ActivityThread.main(ActivityThread.java:5336)

05-15 16:17:14.107: E/AndroidRuntime(20715): at java.lang.reflect.Method.invokeNative(Native Method)

05-15 16:17:14.107: E/AndroidRuntime(20715): at java.lang.reflect.Method.invoke(Method.java:511)

05-15 16:17:14.107: E/AndroidRuntime(20715): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:833)

05-15 16:17:14.107: E/AndroidRuntime(20715): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:600)

05-15 16:17:14.107: E/AndroidRuntime(20715): at dalvik.system.NativeStart.main(Native Method)

05-15 16:17:14.107: E/AndroidRuntime(20715): Caused by: java.lang.NullPointerException

05-15 16:17:14.107: E/AndroidRuntime(20715): at android.content.ContextWrapper.getContentResolver(ContextWrapper.java:99)

05-15 16:17:14.107: E/AndroidRuntime(20715): at android.app.Activity.managedQuery(Activity.java:1751)

05-15 16:17:14.107: E/AndroidRuntime(20715): at com.example.atu_proto.CallLogsRetrieve.getCallDetails(CallLogsRetrieve.java:89)

05-15 16:17:14.107: E/AndroidRuntime(20715): at com.example.atu_proto.MenuList.onCreate(MenuList.java:78)

05-15 16:17:14.107: E/AndroidRuntime(20715): at android.app.Activity.performCreate(Activity.java:5122)

05-15 16:17:14.107: E/AndroidRuntime(20715): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1081)

05-15 16:17:14.107: E/AndroidRuntime(20715): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2277) 05-15 16:17:14.107: E/AndroidRuntime(20715): ... 11 more

Answer 1

05-15 16:17:14.107: E/AndroidRuntime(20715): Caused by: java.lang.NullPointerException

05-15 16:17:14.107: E/AndroidRuntime(20715): at android.content.ContextWrapper.getContentResolver(ContextWrapper.java:99)

...

05-15 16:17:14.107: E/AndroidRuntime(20715): at com.example.atu_proto.CallLogsRetrieve.getCallDetails(CallLogsRetrieve.java:89)

05-15 16:17:14.107: E/AndroidRuntime(20715): at com.example.atu_proto.MenuList.onCreate(MenuList.java:78)

This suggests you're calling another activity from your MenuList activity, likely creating the other activity with new.

Never instantiate activities with new.

In this case it seems CallLogsRetrieve should not be an activity and you could pass in an Activity reference as an argument to methods that need it.