https://github.com/yabushi/TimeStampCamera

自分で書いた部分↓
https://github.com/yabushi/TimeStampCamera/blob/4b4c441675a6a5e7d6b2cf1f0448e19b1a115fd7/app/src/main/java/com/example/shigeki/timestampcamera/MainActivity.java

のプログラムをRUNしようとすると「Android端末には問題が発生したのでTimeStampCameraを終了します」と表示され、以下のエラーが出ます。

72行目の characteristics.get(CameraCharacteristics.LENS_FACING)の部分に問題がありそうだとは思いましたが、解決方法がわかりません。
よろしくお願いします。

E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.example.shigeki.timestampcamera, PID: 867
    java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.shigeki.timestampcamera/com.example.shigeki.timestampcamera.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:2366)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2517)
        at android.app.ActivityThread.access$800(ActivityThread.java:162)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1412)
        at android.os.Handler.dispatchMessage(Handler.java:106)
        at android.os.Looper.loop(Looper.java:189)
        at android.app.ActivityThread.main(ActivityThread.java:5529)
        at java.lang.reflect.Method.invoke(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:372)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:950)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:745)
     Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.Window$Callback android.view.Window.getCallback()' on a null object reference
        at android.support.v7.app.AppCompatDelegateImplBase.<init>(AppCompatDelegateImplBase.java:117)
        at android.support.v7.app.AppCompatDelegateImplV9.<init>(AppCompatDelegateImplV9.java:149)
        at android.support.v7.app.AppCompatDelegateImplV14.<init>(AppCompatDelegateImplV14.java:56)
        at android.support.v7.app.AppCompatDelegate.create(AppCompatDelegate.java:202)
        at android.support.v7.app.AppCompatDelegate.create(AppCompatDelegate.java:183)
        at android.support.v7.app.AppCompatActivity.getDelegate(AppCompatActivity.java:519)
        at android.support.v7.app.AppCompatActivity.findViewById(AppCompatActivity.java:190)
        at com.example.shigeki.timestampcamera.MainActivity.<init>(MainActivity.java:46)
        at java.lang.reflect.Constructor.newInstance(Native Method)
        at java.lang.Class.newInstance(Class.java:1572)
        at android.app.Instrumentation.newActivity(Instrumentation.java:1065)
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2356)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2517) 
        at android.app.ActivityThread.access$800(ActivityThread.java:162) 
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1412) 
        at android.os.Handler.dispatchMessage(Handler.java:106) 
        at android.os.Looper.loop(Looper.java:189) 
        at android.app.ActivityThread.main(ActivityThread.java:5529) 
        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:950) 
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:745)