android - getActionBar().setDisplayHomeAsUpEnabled(true); throws NullPointerException on new activity creation (Google - Basic Tutorial) -


i following this tutorial , getting nullpointerexception @ oncreate method of displaymessageactivity @ block of code:

if (build.version.sdk_int >= build.version_codes.honeycomb) { // show button in action bar. getactionbar().setdisplayhomeasupenabled(true); //exception here }

i running app @ emulator following nexusone avd template.
when click send button text typed in exception.

here log:

09-03 23:02:07.586: e/androidruntime(7095): fatal exception: main 09-03 23:02:07.586: e/androidruntime(7095): java.lang.runtimeexception: unable start activity componentinfo{com.mypackage.myfirstapp/com.mypackage.myfirstapp.displaymessageactivity}: java.lang.nullpointerexception 09-03 23:02:07.586: e/androidruntime(7095):     @ android.app.activitythread.performlaunchactivity(activitythread.java:2180) 09-03 23:02:07.586: e/androidruntime(7095):     @ android.app.activitythread.handlelaunchactivity(activitythread.java:2230) 09-03 23:02:07.586: e/androidruntime(7095):     @ android.app.activitythread.access$600(activitythread.java:141) 09-03 23:02:07.586: e/androidruntime(7095):     @ android.app.activitythread$h.handlemessage(activitythread.java:1234) 09-03 23:02:07.586: e/androidruntime(7095):     @ android.os.handler.dispatchmessage(handler.java:99) 09-03 23:02:07.586: e/androidruntime(7095):     @ android.os.looper.loop(looper.java:137) 09-03 23:02:07.586: e/androidruntime(7095):     @ android.app.activitythread.main(activitythread.java:5041) 09-03 23:02:07.586: e/androidruntime(7095):     @ java.lang.reflect.method.invokenative(native method) 09-03 23:02:07.586: e/androidruntime(7095):     @ java.lang.reflect.method.invoke(method.java:511) 09-03 23:02:07.586: e/androidruntime(7095):     @ com.android.internal.os.zygoteinit$methodandargscaller.run(zygoteinit.java:793) 09-03 23:02:07.586: e/androidruntime(7095):     @ com.android.internal.os.zygoteinit.main(zygoteinit.java:560) 09-03 23:02:07.586: e/androidruntime(7095):     @ dalvik.system.nativestart.main(native method) 09-03 23:02:07.586: e/androidruntime(7095): caused by: java.lang.nullpointerexception 09-03 23:02:07.586: e/androidruntime(7095):     @ com.mypackage.myfirstapp.displaymessageactivity.oncreate(displaymessageactivity.java:40) 09-03 23:02:07.586: e/androidruntime(7095):     @ android.app.activity.performcreate(activity.java:5104) 09-03 23:02:07.586: e/androidruntime(7095):     @ android.app.instrumentation.callactivityoncreate(instrumentation.java:1080) 09-03 23:02:07.586: e/androidruntime(7095):     @ android.app.activitythread.performlaunchactivity(activitythread.java:2144) 09-03 23:02:07.586: e/androidruntime(7095):     ... 11 more

by commenting block app runs successfuly.

why nullpointerexception thrown?

you using theme doesn't support actionbar. hence getactionbar() method throws nullpointerexception.

trying using theme:

android:theme="@android:style/theme.holo.light"

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