java - Unfortunately app stopped working in Android emulator -
this question has answer here:
the ui portion alone worked fine, later when wrote onclicklistener , ran code got error stating "unfortunately app stopped working".
i re-tried new project again getting these error. have attached xml, mainactivity class , logs well. kindly me out. have been stuck simple program whole week. :(
log:
05-18 01:54:31.015: d/android :(1436): oncreate() event 05-18 01:54:31.015: d/androidruntime(1436): shutting down vm 05-18 01:54:31.015: w/dalvikvm(1436): threadid=1: thread exiting uncaught exception (group=0xb2afaba8) 05-18 01:54:31.055: e/androidruntime(1436): fatal exception: main 05-18 01:54:31.055: e/androidruntime(1436): process: com.example.test3, pid: 1436 05-18 01:54:31.055: e/androidruntime(1436): java.lang.runtimeexception: unable start activity componentinfo{com.example.test3/com.example.test3.mainactivity}: java.lang.nullpointerexception 05-18 01:54:31.055: e/androidruntime(1436): @ android.app.activitythread.performlaunchactivity(activitythread.java:2195) 05-18 01:54:31.055: e/androidruntime(1436): @ android.app.activitythread.handlelaunchactivity(activitythread.java:2245) 05-18 01:54:31.055: e/androidruntime(1436): @ android.app.activitythread.access$800(activitythread.java:135) 05-18 01:54:31.055: e/androidruntime(1436): @ android.app.activitythread$h.handlemessage(activitythread.java:1196) 05-18 01:54:31.055: e/androidruntime(1436): @ android.os.handler.dispatchmessage(handler.java:102) 05-18 01:54:31.055: e/androidruntime(1436): @ android.os.looper.loop(looper.java:136) 05-18 01:54:31.055: e/androidruntime(1436): @ android.app.activitythread.main(activitythread.java:5017) 05-18 01:54:31.055: e/androidruntime(1436): @ java.lang.reflect.method.invokenative(native method) 05-18 01:54:31.055: e/androidruntime(1436): @ java.lang.reflect.method.invoke(method.java:515) 05-18 01:54:31.055: e/androidruntime(1436): @ com.android.internal.os.zygoteinit$methodandargscaller.run(zygoteinit.java:779) 05-18 01:54:31.055: e/androidruntime(1436): @ com.android.internal.os.zygoteinit.main(zygoteinit.java:595) 05-18 01:54:31.055: e/androidruntime(1436): @ dalvik.system.nativestart.main(native method) 05-18 01:54:31.055: e/androidruntime(1436): caused by: java.lang.nullpointerexception 05-18 01:54:31.055: e/androidruntime(1436): @ com.example.test3.mainactivity.oncreate(mainactivity.java:25) 05-18 01:54:31.055: e/androidruntime(1436): @ android.app.activity.performcreate(activity.java:5231) 05-18 01:54:31.055: e/androidruntime(1436): @ android.app.instrumentation.callactivityoncreate(instrumentation.java:1087) 05-18 01:54:31.055: e/androidruntime(1436): @ android.app.activitythread.performlaunchactivity(activitythread.java:2159) 05-18 01:54:31.055: e/androidruntime(1436): ... 11 more --- i not sure if wrong mainactivity.java.i attaching xml file , mainactivity.java here getting clear picture.
mainactivity.java:
package com.example.test3; import android.app.activity; import android.os.bundle; import android.util.log; import android.view.view; import android.widget.button; import android.widget.textview; public class mainactivity extends activity { string msg = "android : "; int counter; button add,sub; textview display; /** called when activity first created. */ @override public void oncreate(bundle savedinstancestate) { super.oncreate(savedinstancestate); setcontentview(r.layout.activity_main); log.d(msg, "the oncreate() event"); counter=0; add=(button) findviewbyid(r.id.addbutton); sub=(button) findviewbyid(r.id.subbutton); display=(textview) findviewbyid(r.id.disp); add.setonclicklistener(new view.onclicklistener() { @override public void onclick(view v) { // todo auto-generated method stub counter++; display.settext("count "+counter); } }); sub.setonclicklistener(new view.onclicklistener() { @override public void onclick(view v) { // todo auto-generated method stub counter--; display.settext("count "+counter); } }); } } xml file :
<relativelayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" android:paddingbottom="@dimen/activity_vertical_margin" android:paddingleft="@dimen/activity_horizontal_margin" android:paddingright="@dimen/activity_horizontal_margin" android:paddingtop="@dimen/activity_vertical_margin" tools:context="com.example.test3.mainactivity$placeholderfragment" > <button android:id="@+id/subbutton" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_above="@+id/disp" android:layout_torightof="@+id/addbutton" android:text="sub 1" /> <button android:id="@+id/addbutton" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_alignparentleft="true" android:layout_alignparenttop="true" android:layout_marginleft="58dp" android:layout_margintop="14dp" android:text="add 1" /> <textview android:id="@+id/disp" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_below="@+id/addbutton" android:layout_centerhorizontal="true" android:layout_margintop="56dp" android:text="count 0" android:textappearance="?android:attr/textappearancelarge" /> </relativelayout>
the cause (guessing) views belong fragment layout. should initialize views in fragment oncreateview below.
the other thing notice counter++ on both button click. should count-- on sub button click
@override public view oncreateview(layoutinflater inflater, viewgroup container, bundle savedinstancestate) { view rootview = inflater.inflate(r.layout.fragment_main, container, false); counter=0; add=(button) rootview.findviewbyid(r.id.add); sub=(button) rootview.findviewbyid(r.id.sub); disp=(textview) rootview.findviewbyid(r.id.display); add.setonclicklistener(new view.onclicklistener() { @override public void onclick(view v) { // todo auto-generated method stub counter++; disp.settext("counter "+counter); } }); sub.setonclicklistener(new view.onclicklistener() { @override public void onclick(view v) { // todo auto-generated method stub counter++; disp.settext("counter "+counter); } }); return rootview; }
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