I'm getting a NullPointerException when I click a button on my Android app -


i’m working on simple quiz app user presented question , can select either true or false answer question. added “show answer” button, when click on button i’m getting following nullpointerexception. think i'm missing in activity_cheat.xml can't figure out what.

05-31 19:30:59.238    5978-5978/com.bignerdranch.android.geoquiz.geoquiz e/androidruntime﹕ fatal exception: main     process: com.bignerdranch.android.geoquiz.geoquiz, pid: 5978     java.lang.nullpointerexception: attempt invoke virtual method 'void android.widget.textview.settext(int)' on null object reference             @ com.bignerdranch.android.geoquiz.geoquiz.cheatactivity$1.onclick(cheatactivity.java:33)             @ android.view.view.performclick(view.java:5197)             @ android.view.view$performclick.run(view.java:20926)             @ android.os.handler.handlecallback(handler.java:739)             @ android.os.handler.dispatchmessage(handler.java:95)             @ android.os.looper.loop(looper.java:145)             @ android.app.activitythread.main(activitythread.java:5942)             @ java.lang.reflect.method.invoke(native method)             @ java.lang.reflect.method.invoke(method.java:372)             @ com.android.internal.os.zygoteinit$methodandargscaller.run(zygoteinit.java:1400)             @ com.android.internal.os.zygoteinit.main(zygoteinit.java:1195)


cheatactivity.java 

package com.bignerdranch.android.geoquiz.geoquiz;  import android.app.activity; import android.os.bundle; import android.view.view; import android.widget.button; import android.widget.textview;   public class cheatactivity extends activity {     private boolean mansweristrue;      private textview manswertextview;     private button mshowanswer;      public static final string extra_answer_is_true =  "com.bignerdranch.android.geoquiz.answer_is_true";      @override     protected void oncreate(bundle savedinstancestate) {         super.oncreate(savedinstancestate);         setcontentview(r.layout.activity_cheat);          mansweristrue = getintent().getbooleanextra(extra_answer_is_true, false);           mshowanswer = (button)findviewbyid(r.id.showanswerbutton);         mshowanswer.setonclicklistener(new view.onclicklistener() {             @override             public void onclick(view v) {                 if (mansweristrue) {                     manswertextview.settext(r.string.true_button);                 } else {                     manswertextview.settext(r.string.false_button);                 }             }         });     }  }

activity_cheat.xml

<?xml version="1.0" encoding="utf-8"?> <linearlayout xmlns:android="http://schemas.android.com/apk/res/android"               android:layout_width="match_parent"               android:layout_height="match_parent">               android:gravity="center">      <textview         android:layout_width="wrap_content"         android:layout_height="wrap_content"         android:padding="24dp"         android:text="@string/warning_text_view" />      <textview         android:id="@+id/answertextview"         android:layout_width="wrap_content"         android:layout_height="wrap_content"         android:padding="24dp" />      <button         android:id="@+id/showanswerbutton"         android:layout_width="wrap_content"         android:layout_height="wrap_content"         android:text="@string/show_answer_button" />   </linearlayout>

manswertextview never initialized. that's why npe.

add

manswertextview = (textview)findviewbyid(r.id.answertextview);

before 

 if (mansweristrue)

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