BigNerdRanch android tutorial, ClassCast exception in geoquiz -
can`t find out bug. application crashes when pressing "cheat" button (starting second activity). throws classcast exception
geoquizactivity.java:
package com.bignerdranch.android.quiz; import android.app.activity; import android.content.intent; import android.os.bundle; import android.util.log; import android.view.view; import android.widget.button; import android.widget.imagebutton; import android.widget.textview; import android.widget.toast; public class geoquizactivity extends activity { /** called when activity first created. */ private static final string tag = "geoquizactivity"; private static final string key_index ="index"; private button mtruebutton; private button mfalsebutton; private button mcheatbutton; private imagebutton mnextbutton; private imagebutton mprevbutton; private textview mquestiontextview; private boolean mischeater; private void updatequestion(){ int question = mquestionbank[mcurrentindex].getquestion(); mquestiontextview.settext(question); } private void checkanswer(boolean userpressedtrue){ boolean answeristrue = mquestionbank[mcurrentindex].istruequestion(); int messageresid = 0; if(mischeater){ messageresid=r.string.judgment_toast; } else{ if (userpressedtrue==answeristrue){ messageresid =r.string.correct_toast; } else{ messageresid = r.string.incorrect_toast; } toast.maketext(this, messageresid, toast.length_short).show(); } } @override protected void onactivityresult(int requestcode, int resultcode, intent data){ if(data==null){ return; } mischeater = data.getbooleanextra(cheatactivity.extra_answer_shown, false); } private truefalse [] mquestionbank = new truefalse[] { new truefalse(r.string.question_oceans, true), new truefalse(r.string.question_mideast, false), new truefalse(r.string.question_africa, false), new truefalse(r.string.question_americas, true), new truefalse(r.string.question_asia, true), }; private int mcurrentindex = 0; @override public void oncreate(bundle savedinstancestate) { log.d(tag, "oncreate(bundle) called"); super.oncreate(savedinstancestate); setcontentview(r.layout.main); if(savedinstancestate != null){ mcurrentindex = savedinstancestate.getint(key_index, 0); } mquestiontextview = (textview)findviewbyid(r.id.question_text_view); mquestiontextview.setonclicklistener(new view.onclicklistener(){ @override public void onclick(view v){ mcurrentindex=(mcurrentindex+1)%mquestionbank.length; updatequestion(); } }); mtruebutton = (button)findviewbyid(r.id.true_button); mtruebutton.setonclicklistener(new view.onclicklistener(){ @override public void onclick (view v){ checkanswer(true); } }); mfalsebutton = (button)findviewbyid(r.id.false_button); mfalsebutton.setonclicklistener(new view.onclicklistener(){ @override public void onclick (view v){ checkanswer(false); } }); mnextbutton =(imagebutton)findviewbyid(r.id.next_button); mnextbutton.setonclicklistener(new view.onclicklistener(){ @override public void onclick (view v){ mcurrentindex= (mcurrentindex+1)%mquestionbank.length; updatequestion(); mischeater=false; } }); mprevbutton = (imagebutton)findviewbyid(r.id.prev_button); mprevbutton.setonclicklistener(new view.onclicklistener(){ @override public void onclick(view v){ if(mcurrentindex==0){ mcurrentindex=mquestionbank.length-1; } else{ mcurrentindex=(mcurrentindex-1); } updatequestion(); mischeater=false; } }); mcheatbutton = (button)findviewbyid(r.id.cheat_button); mcheatbutton.setonclicklistener(new view.onclicklistener() { @override public void onclick(view v) { intent = new intent(geoquizactivity.this, cheatactivity.class); boolean answeristrue = mquestionbank[mcurrentindex].istruequestion(); i.putextra(cheatactivity.extra_answer_is_true, answeristrue); startactivityforresult(i, 0); } }); updatequestion(); } @override public void onsaveinstancestate(bundle savedinstancestate){ super.onsaveinstancestate(savedinstancestate); log.i(tag, "onsaveinstancestate"); savedinstancestate.putint(key_index, mcurrentindex); } @override public void onstart(){ super.onstart(); log.d(tag, "onstart() called"); } @override public void onpause(){ super.onpause(); log.d(tag, "onpause() called"); } @override public void onresume(){ super.onresume(); log.d(tag, "onresume() called"); } @override public void onstop(){ super.onstop(); log.d(tag, "onstop() called"); } @override public void ondestroy(){ super.ondestroy(); log.d(tag, "ondestroy() called"); } }cheatactivity.java:
package com.bignerdranch.android.quiz; import android.app.activity; import android.content.intent; 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.quiz.answer_is_true"; public static final string extra_answer_shown = "com.bignerdranch.android.quiz.answer_shown"; private void setanswershownresult(boolean isanswershown){ intent data = new intent(); data.putextra(extra_answer_shown, isanswershown); setresult(result_ok, data); } @override protected void oncreate(bundle savedinstancestate){ super.oncreate(savedinstancestate); setcontentview(r.layout.activity_cheat); mansweristrue = getintent().getbooleanextra(extra_answer_is_true, true); manswertextview = (textview)findviewbyid(r.id.answertextview); mshowanswer = (button)findviewbyid(r.id.showanswerbutton); setanswershownresult(false); 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); } setanswershownresult(true); } }); } }main.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" android:orientation="vertical" > <textview android:layout_width="wrap_content" android:layout_height="wrap_content" android:padding="24dp" android:id="@+id/question_text_view" /> <linearlayout android:layout_width="wrap_content" android:layout_height="wrap_content" android:orientation="horizontal" > <button android:id="@+id/true_button" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="@string/true_button" /> <button android:id="@+id/false_button" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="@string/false_button" /> </linearlayout> <linearlayout android:layout_width="wrap_content" android:layout_height="wrap_content" android:orientation="horizontal"> <imagebutton android:id="@+id/prev_button" android:layout_width="wrap_content" android:layout_height="wrap_content" android:contentdescription="@string/prev_button" android:src="@drawable/arrow_left" /> <imagebutton android:id="@+id/next_button" android:layout_width="wrap_content" android:layout_height="wrap_content" android:contentdescription="@string/next_button" android:src="@drawable/arrow_right" /> <button android:id="@+id/cheat_button" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="@string/cheat_button"/> </linearlayout> </linearlayout><?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:orientation="vertical" android:gravity="center"> <textview android:layout_width="wrap_content" android:layout_height="wrap_content" android:padding="24dp" android:text="@string/warning_text"/> <textview android:id="@+id/answertextview" android:layout_width="wrap_content" android:layout_height="wrap_content" android:padding="24dp"/> <textview android:id="@+id/showanswerbutton" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="@string/show_answer_button"/> </linearlayout>thanks!
edit: logcat: dont know line causes exception or how find it. in logcat, its in 3rd line top.
05-15 15:32:57.116: w/dalvikvm(349): threadid=1: thread exiting uncaught exception (group=0x40015560) 05-15 15:32:57.256: e/androidruntime(349): fatal exception: main 05-15 15:32:57.256: e/androidruntime(349): java.lang.runtimeexception: unable start activity componentinfo{com.bignerdranch.android.quiz/com.bignerdranch.android.quiz.cheatactivity}: java.lang.classcastexception: android.widget.textview 05-15 15:32:57.256: e/androidruntime(349): at android.app.activitythread.performlaunchactivity(activitythread.java:1647) 05-15 15:32:57.256: e/androidruntime(349): at android.app.activitythread.handlelaunchactivity(activitythread.java:1663) 05-15 15:32:57.256: e/androidruntime(349): at android.app.activitythread.access$1500(activitythread.java:117) 05-15 15:32:57.256: e/androidruntime(349): at android.app.activitythread$h.handlemessage(activitythread.java:931) 05-15 15:32:57.256: e/androidruntime(349): at android.os.handler.dispatchmessage(handler.java:99) 05-15 15:32:57.256: e/androidruntime(349): at android.os.looper.loop(looper.java:123) 05-15 15:32:57.256: e/androidruntime(349): at android.app.activitythread.main(activitythread.java:3683) 05-15 15:32:57.256: e/androidruntime(349): at java.lang.reflect.method.invokenative(native method) 05-15 15:32:57.256: e/androidruntime(349): at java.lang.reflect.method.invoke(method.java:507) 05-15 15:32:57.256: e/androidruntime(349): at com.android.internal.os.zygoteinit$methodandargscaller.run(zygoteinit.java:839) 05-15 15:32:57.256: e/androidruntime(349): at com.android.internal.os.zygoteinit.main(zygoteinit.java:597) 05-15 15:32:57.256: e/androidruntime(349): at dalvik.system.nativestart.main(native method) 05-15 15:32:57.256: e/androidruntime(349): caused by: java.lang.classcastexception: android.widget.textview 05-15 15:32:57.256: e/androidruntime(349): at com.bignerdranch.android.quiz.cheatactivity.oncreate(cheatactivity.java:28) 05-15 15:32:57.256: e/androidruntime(349): at android.app.instrumentation.callactivityoncreate(instrumentation.java:1047) 05-15 15:32:57.256: e/androidruntime(349): at android.app.activitythread.performlaunchactivity(activitythread.java:1611) 05-15 15:32:57.256: e/androidruntime(349): ... 11 more
logcat friend:
... @ com.bignerdranch.android.quiz.cheatactivity.oncreate(cheatactivity.java:28) ... apparently, you're trying cast object class it's not assignable from. check cheatactivity.java, line 28.
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