OnClickListener in android app fails -

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when start android application on smartphone system closing app , says: "sorry. yourapplication closed."

it because of onclicklistener, why?

here code:

@override protected void oncreate(bundle savedinstancestate) {     super.oncreate(savedinstancestate);     setcontentview(r.layout.activity_main);      button addtodo = (button) findviewbyid((r.id.addtodobutton));     button cancel = (button) findviewbyid(r.id.cancel);      cancel.setonclicklistener(new onclicklistener() {         @override         public void onclick(view view) {             system.out.println("seas!");         }     }); }

stack trace:

java.lang.runtimeexception: unable start activity componentinfo{sstodo.app/sstodo.app.mainactivity}: java.lang.nullpointerexception         @ android.app.activitythread.performlaunchactivity(activitythread.java:2266)         @ android.app.activitythread.handlelaunchactivity(activitythread.java:2316)         @ android.app.activitythread.access$600(activitythread.java:150)         @ android.app.activitythread$h.handlemessage(activitythread.java:1298)         @ android.os.handler.dispatchmessage(handler.java:99)         @ android.os.looper.loop(looper.java:213)         @ android.app.activitythread.main(activitythread.java:5225)         @ java.lang.reflect.method.invokenative(native method)         @ java.lang.reflect.method.invoke(method.java:525)         @ com.android.internal.os.zygoteinit$methodandargscaller.run(zygoteinit.java:741)         @ com.android.internal.os.zygoteinit.main(zygoteinit.java:557)         @ dalvik.system.nativestart.main(native method)  caused by: java.lang.nullpointerexception         @ sstodo.app.mainactivity.oncreate(mainactivity.java:24)         @ android.app.activity.performcreate(activity.java:5133)         @ android.app.instrumentation.callactivityoncreate(instrumentation.java:1087)         @ android.app.activitythread.performlaunchactivity(activitythread.java:2230)

buttons (used in alet dialog):

<button         android:id="@+id/addtodobutton"         android:text="@string/add"         android:layout_width="fill_parent"         android:layout_height="wrap_content"         android:layout_weight="1"         android:clickable="true"         style="@style/addbuttonstyle"         />      <button         android:id="@+id/cancel"         android:text="@string/cancel"         android:layout_width="fill_parent"         android:layout_height="wrap_content"         android:layout_weight="1"         android:clickable="true"         style="@style/cancelbuttonstyle"         />

    

try changing code this

cancel.setonclicklistener(new view. onclicklistener() {  @override  public void onclick(view view)  {  system.out.println("seas!"); }  });

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