04-19 10:18:47.895 5888-5888/com.example.kotlinfirstsampleapp E/AndroidRuntime: FATAL EXCEPTION: main
                                                                                Process: com.example.kotlinfirstsampleapp, PID: 5888
                                                                                java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.kotlinfirstsampleapp/com.example.kotlinfirstsampleapp.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.Window$Callback android.view.Window.getCallback()' on a null object reference
                                                                                    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2327)
                                                                                    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)
                                                                                    at android.app.ActivityThread.-wrap11(ActivityThread.java)
                                                                                    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
                                                                                    at android.os.Handler.dispatchMessage(Handler.java:102)
                                                                                    at android.os.Looper.loop(Looper.java:148)
                                                                                    at android.app.ActivityThread.main(ActivityThread.java:5417)
                                                                                    at java.lang.reflect.Method.invoke(Native Method)
                                                                                    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
                                                                                    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
                                                                                 Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.Window$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:151)
                                                                                    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.AppCompatDelegateImplV23.<init>(AppCompatDelegateImplV23.java:33)
                                                                                    at android.support.v7.app.AppCompatDelegate.create(AppCompatDelegate.java:203)
                                                                                    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.example.kotlinfirstsampleapp.MainActivity.<init>(MainActivity.kt:49)
                                                                                    at java.lang.Class.newInstance(Native Method)
                                                                                    at android.app.Instrumentation.newActivity(Instrumentation.java:1067)
                                                                                    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2317)
                                                                                    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)
                                                                                    at android.app.ActivityThread.-wrap11(ActivityThread.java)
                                                                                    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
                                                                                    at android.os.Handler.dispatchMessage(Handler.java:102)
                                                                                    at android.os.Looper.loop(Looper.java:148)
                                                                                    at android.app.ActivityThread.main(ActivityThread.java:5417)
                                                                                    at java.lang.reflect.Method.invoke(Native Method)
                                                                                    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
                                                                                    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)