java - In Activity.onCreate(), why does Intent.getExtras() sometimes return null? -

this false alarm, see my own answer. original question below:

an activity has button takes user activity. launch new activity, populate our intent extras, , oncreate(), new activity reads extras via intent.getextras(). assumed returned bundle non-null, customer crash reports discovered, getextras() returns null.

null-guarding extras, this answer shows, fine, if populate intent's extras, why ever return null later? there better place (like onresume()) read extras?

edit: may because not following name convention required keys:

the name must include package prefix, example app com.android.contacts use names "com.android.contacts.showall".

this intent.putextras javadoc. happens if don't follow name convention; behavior defined?

here's relevant code:

class fromactivity extends activity {      imagebutton button;      @override     public void oncreate(bundle savedinstancestate) {         super.oncreate(savedinstancestate);         setcontentview(r.layout.from_view);          button = (imagebutton)findviewbyid(r.id.button);         button.setvisibility(view.visible);         button.setonclicklistener(new view.onclicklistener() {             @override             public void onclick(view v) {                 intent = new intent(fromactivity.this, toactivity.class);                 i.putextra(toactivity.server_param, ...);                 i.putextra(toactivity.uuid_param, ...);                 i.putextra(toactivity.template_param, ...);                 startactivityforresult(i, 0);                  overridetransition(r.anim.slide_left_in, r.anim.slide_left_out);             }         });     }  }  class toactivity extends activity {      public static final string server_param = "server";     public static final string uuid_param = "uuid";     public static final string template_param = "template";      @override     public void oncreate(bundle savedinstancestate) {         super.oncreate(savedinstancestate);          bundle extras = getintent().getextras();         if (extras == null) {             finish();             return;         }          // stuff extras     } } 

here sample stack trace of problem:

java.lang.runtimeexception: unable start activity componentinfo{toactivity}: java.lang.nullpointerexception     @  android.app.activitythread.performlaunchactivity(activitythread.java:2355)     @  android.app.activitythread.handlelaunchactivity(activitythread.java:2391)     @  android.app.activitythread.access$600(activitythread.java:151)     @  android.app.activitythread$h.handlemessage(activitythread.java:1335)     @  android.os.handler.dispatchmessage(handler.java:99)     @  android.os.looper.loop(looper.java:155)     @  android.app.activitythread.main(activitythread.java:5493)     @  java.lang.reflect.method.invokenative(native method)     @  java.lang.reflect.method.invoke(method.java:511)     @  com.android.internal.os.zygoteinit$methodandargscaller.run(zygoteinit.java:1028)     @  com.android.internal.os.zygoteinit.main(zygoteinit.java:795)     @  dalvik.system.nativestart.main(native method)      caused by: java.lang.nullpointerexception     @  toactivity.oncreate(sourcefile:49)     @  android.app.activity.performcreate(activity.java:5066)     @  android.app.instrumentation.callactivityoncreate(instrumentation.java:1101)     @  android.app.activitythread.performlaunchactivity(activitythread.java:2311)      ... 11 more      java.lang.nullpointerexception     @  toactivity.oncreate(sourcefile:49)     @  android.app.activity.performcreate(activity.java:5066)     @  android.app.instrumentation.callactivityoncreate(instrumentation.java:1101)     @  android.app.activitythread.performlaunchactivity(activitythread.java:2311)     @  android.app.activitythread.handlelaunchactivity(activitythread.java:2391)     @  android.app.activitythread.access$600(activitythread.java:151)     @  android.app.activitythread$h.handlemessage(activitythread.java:1335)     @  android.os.handler.dispatchmessage(handler.java:99)     @  android.os.looper.loop(looper.java:155)     @  android.app.activitythread.main(activitythread.java:5493)     @  java.lang.reflect.method.invokenative(native method)     @  java.lang.reflect.method.invoke(method.java:511)     @  com.android.internal.os.zygoteinit$methodandargscaller.run(zygoteinit.java:1028)     @  com.android.internal.os.zygoteinit.main(zygoteinit.java:795)     @  dalvik.system.nativestart.main(native method) 

you can this:

getintent().getstringextra(key); 

or:

getintent().getextras().getstring(key) 

and set in "fromactivity":

bundle extras = new bundle(); extras.putstring(key, value); intent.putextras(extras); //and start activity... 

or:

intent.putextra(key, string); //and start activity... 

either way should work, hope helps...

regards!