FATAL EXCEPTION: main
                                                                               Process: com.esame.itraining.itraining, PID: 24141
                                                                               java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.esame.itraining.itraining/com.esame.itraining.itraining.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.Window$Callback android.view.Window.getCallback()' on a null object reference
                                                                                   at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2373)
                                                                                   at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2524)
                                                                                   at android.app.ActivityThread.access$800(ActivityThread.java:167)
                                                                                   at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1419)
                                                                                   at android.os.Handler.dispatchMessage(Handler.java:111)
                                                                                   at android.os.Looper.loop(Looper.java:194)
                                                                                   at android.app.ActivityThread.main(ActivityThread.java:5546)
                                                                                   at java.lang.reflect.Method.invoke(Native Method)
                                                                                   at java.lang.reflect.Method.invoke(Method.java:372)
                                                                                   at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:964)
                                                                                   at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:759)
                                                                                Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.Window$Callback android.view.Window.getCallback()' on a null object reference
                                                                                   at android.support.v7.app.AppCompatDelegateImplBase.<init>(AppCompatDelegateImplBase.java:120)
                                                                                   at android.support.v7.app.AppCompatDelegateImplV9.<init>(AppCompatDelegateImplV9.java:155)
                                                                                   at android.support.v7.app.AppCompatDelegateImplV11.<init>(AppCompatDelegateImplV11.java:31)
                                                                                   at android.support.v7.app.AppCompatDelegateImplV14.<init>(AppCompatDelegateImplV14.java:55)
                                                                                   at android.support.v7.app.AppCompatDelegate.create(AppCompatDelegate.java:205)
                                                                                   at android.support.v7.app.AppCompatDelegate.create(AppCompatDelegate.java:185)
                                                                                   at android.support.v7.app.AppCompatActivity.getDelegate(AppCompatActivity.java:519)
                                                                                   at android.support.v7.app.AppCompatActivity.findViewById(AppCompatActivity.java:190)
                                                                                   at com.esame.itraining.itraining.MainActivity.<init>(MainActivity.java:33)
                                                                                   at java.lang.reflect.Constructor.newInstance(Native Method)
                                                                                   at java.lang.Class.newInstance(Class.java:1572)
                                                                                   at android.app.Instrumentation.newActivity(Instrumentation.java:1070)
                                                                                   at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2363)
                                                                                   at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2524)
                                                                                   at android.app.ActivityThread.access$800(ActivityThread.java:167)
                                                                                   at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1419)
                                                                                   at android.os.Handler.dispatchMessage(Handler.java:111)
                                                                                   at android.os.Looper.loop(Looper.java:194)
                                                                                   at android.app.ActivityThread.main(ActivityThread.java:5546)
                                                                                   at java.lang.reflect.Method.invoke(Native Method)
                                                                                   at java.lang.reflect.Method.invoke(Method.java:372)
                                                                                   at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:964)
                                                                                   at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:759)