android - Caused by: java.lang.NullPointerException on onClickListener -
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i try create 1 onclicklistener multiple button , take following error
06-27 20:12:27.468: d/androidruntime(4810): shutting down vm 06-27 20:12:27.468: w/dalvikvm(4810): threadid=1: thread exiting uncaught exception (group=0x415caba8) 06-27 20:12:27.468: e/androidruntime(4810): fatal exception: main 06-27 20:12:27.468: e/androidruntime(4810): process: com.example.calculatorrr, pid: 4810 06-27 20:12:27.468: e/androidruntime(4810): java.lang.runtimeexception: unable start activity componentinfo{com.example.calculatorrr/com.example.calculatorrr.mainactivity}: java.lang.nullpointerexception 06-27 20:12:27.468: e/androidruntime(4810): @ android.app.activitythread.performlaunchactivity(activitythread.java:2184) 06-27 20:12:27.468: e/androidruntime(4810): @ android.app.activitythread.handlelaunchactivity(activitythread.java:2233) 06-27 20:12:27.468: e/androidruntime(4810): @ android.app.activitythread.access$800(activitythread.java:135) 06-27 20:12:27.468: e/androidruntime(4810): @ android.app.activitythread$h.handlemessage(activitythread.java:1196) 06-27 20:12:27.468: e/androidruntime(4810): @ android.os.handler.dispatchmessage(handler.java:102) 06-27 20:12:27.468: e/androidruntime(4810): @ android.os.looper.loop(looper.java:136) 06-27 20:12:27.468: e/androidruntime(4810): @ android.app.activitythread.main(activitythread.java:5001) 06-27 20:12:27.468: e/androidruntime(4810): @ java.lang.reflect.method.invokenative(native method) 06-27 20:12:27.468: e/androidruntime(4810): @ java.lang.reflect.method.invoke(method.java:515) 06-27 20:12:27.468: e/androidruntime(4810): @ com.android.internal.os.zygoteinit$methodandargscaller.run(zygoteinit.java:785) 06-27 20:12:27.468: e/androidruntime(4810): @ com.android.internal.os.zygoteinit.main(zygoteinit.java:601) 06-27 20:12:27.468: e/androidruntime(4810): @ dalvik.system.nativestart.main(native method) 06-27 20:12:27.468: e/androidruntime(4810): caused by: java.lang.nullpointerexception 06-27 20:12:27.468: e/androidruntime(4810): @ com.example.calculatorrr.mainactivity.oncreate(mainactivity.java:426) 06-27 20:12:27.468: e/androidruntime(4810): @ android.app.activity.performcreate(activity.java:5231) 06-27 20:12:27.468: e/androidruntime(4810): @ android.app.instrumentation.callactivityoncreate(instrumentation.java:1087) 06-27 20:12:27.468: e/androidruntime(4810): @ android.app.activitythread.performlaunchactivity(activitythread.java:2148) 06-27 20:12:27.468: e/androidruntime(4810): ... 11 more my main activitiy class this:
public class mainactivity extends actionbaractivity { @override protected void oncreate(bundle savedinstancestate) { super.oncreate(savedinstancestate); setcontentview(r.layout.activity_main); if (savedinstancestate == null) { getsupportfragmentmanager().begintransaction() .add(r.id.container, new placeholderfragment()).commit(); } framelayout mframelayout = (framelayout)findviewbyid(r.id.container); button mbutton0 = (button) mframelayout.findviewbyid(r.id.bt0); log.i("test1", mbutton0.tostring()); button mbutton1 = (button) mframelayout.findviewbyid(r.id.bt1); button mbutton2 = (button) mframelayout.findviewbyid(r.id.bt2); button mbutton3 = (button) mframelayout.findviewbyid(r.id.bt3); button mbutton4 = (button) mframelayout.findviewbyid(r.id.bt4); button mbutton5 = (button) mframelayout.findviewbyid(r.id.bt5); button mbutton6 = (button) mframelayout.findviewbyid(r.id.bt6); button mbutton7 = (button) mframelayout.findviewbyid(r.id.bt7); button mbutton8 = (button) mframelayout.findviewbyid(r.id.bt8); button mbutton9 = (button) mframelayout.findviewbyid(r.id.bt9); button mbuttonmul = (button) mframelayout.findviewbyid(r.id.bt_multiplication); button mbuttonplu = (button) mframelayout.findviewbyid(r.id.bt_plus); button mbuttonmin = (button) mframelayout.findviewbyid(r.id.btminus); button mbuttondiv = (button) mframelayout.findviewbyid(r.id.bt_divide); mbutton0.setonclicklistener(onclicklistener); mbutton1.setonclicklistener(onclicklistener); mbutton2.setonclicklistener(onclicklistener); mbutton3.setonclicklistener(onclicklistener); mbutton4.setonclicklistener(onclicklistener); mbutton5.setonclicklistener(onclicklistener); mbutton6.setonclicklistener(onclicklistener); mbutton7.setonclicklistener(onclicklistener); mbutton8.setonclicklistener(onclicklistener); mbutton9.setonclicklistener(onclicklistener); mbuttonmul.setonclicklistener(onclicklistener); mbuttonplu.setonclicklistener(onclicklistener); mbuttonmin.setonclicklistener(onclicklistener); mbuttondiv.setonclicklistener(onclicklistener); } private view.onclicklistener onclicklistener = new view.onclicklistener() { @override public void onclick(view v) { textview txtview = (textview) findviewbyid(r.id.txt1); string message = txtview.gettext().tostring(); switch (v.getid()) { case r.id.bt0: message = message + "0"; break; case r.id.bt1: message = message + "1"; break; case r.id.bt2: message = message + "2"; break; case r.id.bt3: message = message + "3"; break; case r.id.bt4: message = message + "4"; break; case r.id.bt5: message = message + "5"; break; case r.id.bt6: message = message + "6"; break; case r.id.bt7: message = message + "7"; break; case r.id.bt8: message = message + "8"; break; case r.id.bt9: message = message + "9"; break; case r.id.bt_multiplication: message = message + "*"; break; case r.id.bt_plus: message = message + "+"; break; case r.id.btminus: message = message + "-"; break; case r.id.bt_divide: message = message + "/"; break; } txtview.settext(message); } }; } my 2 resource files is:
activity_main.xml:
<framelayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:id="@+id/container" android:layout_width="match_parent" android:layout_height="match_parent" tools:context="com.example.calculatorrr.mainactivity" tools:ignore="mergerootframe" /> and fragment_main.xml:
<linearlayout xmlns:android="http://schemas.android.com/apk/res/android" android:orientation="vertical" android:layout_width="match_parent" android:layout_height="match_parent" > <textview android:id="@+id/txt1" android:layout_width="match_parent" android:layout_height="66dp" android:background="@android:color/darker_gray" android:hint="0" android:textsize="40dp" /> ........ other butttons i have search on google , here button nothing works far! maybe obvious didn't see! attention!
edit: line error:
mbutton0.setonclicklistener(onclicklistener);
in onclicklistener textview tx1 in null,because textview txt1 part of fragment not activity_main.
so either use tx1 in activity_main layout. or use in oncreateview method of fragment.
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