错误无法启动活动

Question

In my application I have three PNG file that I use as the background of the activity, placed in the folder drawable-nodpi, but the application crashes on tablet Samsung Galaxy Tab 2 10.1, that i used for test and gives me this error:

LogCat:

E/AndroidRuntime(4846): FATAL EXCEPTION: main
E/AndroidRuntime(4846): java.lang.RuntimeException: Unable to start activity ComponentInfo{it.bisemanuDEV.mathTools/it.bisemanuDEV.mathTools.MainActivity}: java.lang.NullPointerException
E/AndroidRuntime(4846):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2097)
E/AndroidRuntime(4846):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2122)
E/AndroidRuntime(4846):     at android.app.ActivityThread.access$600(ActivityThread.java:140)
E/AndroidRuntime(4846):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1228)
E/AndroidRuntime(4846):     at android.os.Handler.dispatchMessage(Handler.java:99)
E/AndroidRuntime(4846):     at android.os.Looper.loop(Looper.java:137)
E/AndroidRuntime(4846):     at android.app.ActivityThread.main(ActivityThread.java:4895)
E/AndroidRuntime(4846):     at java.lang.reflect.Method.invokeNative(Native Method)
E/AndroidRuntime(4846):     at java.lang.reflect.Method.invoke(Method.java:511)
E/AndroidRuntime(4846):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:994)
E/AndroidRuntime(4846):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:761)
E/AndroidRuntime(4846):     at dalvik.system.NativeStart.main(Native Method)
E/AndroidRuntime(4846): Caused by: java.lang.NullPointerException
E/AndroidRuntime(4846):     at it.bisemanuDEV.mathTools.MainActivity.onCreate(MainActivity.java:53)
E/AndroidRuntime(4846):     at android.app.Activity.performCreate(Activity.java:5163)
E/AndroidRuntime(4846):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1094)
E/AndroidRuntime(4846):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2061)

But the application works on different models of smartphones. What could be the problem?

Answer 1

You've got a NullPointerException:

Caused by: java.lang.NullPointerException
E/AndroidRuntime(4846):     at it.bisemanuDEV.mathTools.MainActivity.onCreate(MainActivity.java:53)

so look at that line 53 to find out what's wrong.