Android Studio: App stürzt ab?

Hallo! Seit neuestem stürzt meine App immer an der gleichen Stelle ab. Habe versucht das Problem selber zu lösen, kam aber zu keiner Lösung. Ich bin über jede Hilfe dankbar :) Hier unten ist meine Logcat:

java.lang.RuntimeException: Unable to start activity ComponentInfo{mycompany.werwolf/mycompany.werwolf.test.Seite2_Karten_Activity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.TextView.setText(java.lang.CharSequence)' on a null object reference
                                                                           at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2452)
                                                                           at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2512)
                                                                           at android.app.ActivityThread.access$900(ActivityThread.java:158)
                                                                           at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1364)
                                                                           at android.os.Handler.dispatchMessage(Handler.java:102)
                                                                           at android.os.Looper.loop(Looper.java:148)
                                                                           at android.app.ActivityThread.main(ActivityThread.java:5521)
                                                                           at java.lang.reflect.Method.invoke(Native Method)
                                                                           at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:804)
                                                                           at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:666)
                                                                        Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.TextView.setText(java.lang.CharSequence)' on a null object reference
                                                                           at mycompany.werwolf.test.Seite2_Karten_Activity.onCreate(Seite2_Karten_Activity.java:230)
                                                                           at android.app.Activity.performCreate(Activity.java:6446)
                                                                           at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1112)
                                                                           at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2405)
                                                                           at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2512) 
                                                                           at android.app.ActivityThread.access$900(ActivityThread.java:158) 
                                                                           at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1364) 
                                                                           at android.os.Handler.disp
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