how to set imagebutton src in onCreateView?

In my app, I have several `ImageButton`s that are controlled by their respective `StateListDrawable`s. I use them as tab menu at the bottom of the activity to switch fragments. They change states just fine (when pressed, focused, default). Switching of fragments also works okay. However, I don't know how can I make a button be highlighted (for example, use the image set when pressed) when the fragment it represents is currently shown. I've tried setting the `BackgroundResource`, `ImageDrawable`, `ImageResource` during runtime but I am getting a `NullPointerException` everytime I launch my app. Here's my log if this helps ``` 05-16 14:15:19.489: E/AndroidRuntime(4800): FATAL EXCEPTION: main 05-16 14:15:19.489: E/AndroidRuntime(4800): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.meralco/com.meralco.pms.TestPMSActivity}: java.lang.NullPointerException 05-16 14:15:19.489: E/AndroidRuntime(4800): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1651) 05-16 14:15:19.489: E/AndroidRuntime(4800): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1667) 05-16 14:15:19.489: E/AndroidRuntime(4800): at android.app.ActivityThread.access$1500(ActivityThread.java:117) 05-16 14:15:19.489: E/AndroidRuntime(4800): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:935) 05-16 14:15:19.489: E/AndroidRuntime(4800): at android.os.Handler.dispatchMessage(Handler.java:99) 05-16 14:15:19.489: E/AndroidRuntime(4800): at android.os.Looper.loop(Looper.java:130) 05-16 14:15:19.489: E/AndroidRuntime(4800): at android.app.ActivityThread.main(ActivityThread.java:3687) 05-16 14:15:19.489: E/AndroidRuntime(4800): at java.lang.reflect.Method.invokeNative(Native Method) 05-16 14:15:19.489: E/AndroidRuntime(4800): at java.lang.reflect.Method.invoke(Method.java:507) 05-16 14:15:19.489: E/AndroidRuntime(4800): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:867) 05-16 14:15:19.489: E/AndroidRuntime(4800): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:625) 05-16 14:15:19.489: E/AndroidRuntime(4800): at dalvik.system.NativeStart.main(Native Method) 05-16 14:15:19.489: E/AndroidRuntime(4800): Caused by: java.lang.NullPointerException 05-16 14:15:19.489: E/AndroidRuntime(4800): at com.meralco.pms.HomeFragment.onCreateView(HomeFragment.java:19) 05-16 14:15:19.489: E/AndroidRuntime(4800): at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:870) 05-16 14:15:19.489: E/AndroidRuntime(4800): at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1080) 05-16 14:15:19.489: E/AndroidRuntime(4800): at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:622) 05-16 14:15:19.489: E/AndroidRuntime(4800): at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1416) 05-16 14:15:19.489: E/AndroidRuntime(4800): at android.support.v4.app.FragmentActivity.onStart(FragmentActivity.java:505) 05-16 14:15:19.489: E/AndroidRuntime(4800): at android.app.Instrumentation.callActivityOnStart(Instrumentation.java:1129) 05-16 14:15:19.489: E/AndroidRuntime(4800): at android.app.Activity.performStart(Activity.java:3791) 05-16 14:15:19.489: E/AndroidRuntime(4800): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1624) 05-16 14:15:19.489: E/AndroidRuntime(4800): ... 11 more ``` Here's HomeFragment.xml: ``` public class HomeFragment extends Fragment { @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { View view = inflater.inflate(R.layout.home, container, false); ImageButton btn_sin = (ImageButton) view.findViewById(R.drawable.button_sin); btn_sin.setBackgroundResource(R.drawable.pp_sin_1); return view; } } ``` home.xml ``` <?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical" android:gravity="center_horizontal|center_vertical" > <TextView android:id="@+id/home_text1" android:layout_width="match_parent" android:layout_height="wrap_content" android:text="@string/home_text1" android:textSize="20sp" android:textStyle="bold" android:textColor="#000000" android:padding="10dp" android:gravity="center_horizontal|center_vertical" /> <TextView android:id="@+id/home_text2" android:layout_width="match_parent" android:layout_height="wrap_content" android:text="@string/home_text2" android:textSize="12sp" android:textColor="#000000" android:paddingLeft="10dp" android:paddingRight="10dp" android:gravity="center_horizontal|center_vertical"/> <TextView android:id="@+id/home_text3" android:layout_width="match_parent" android:layout_height="wrap_content" android:text="@string/home_text3" android:textSize="10sp" android:textColor="#000000" android:padding="15dp" android:textStyle="italic" android:gravity="center_horizontal|center_vertical"/> </LinearLayout> ``` main.xml: ``` <?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:orientation="vertical" android:layout_width="match_parent" android:layout_height="match_parent"> <ImageView android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_weight="0.3" android:src="@drawable/phone_portrait_bg_01" /> <FrameLayout android:id="@+id/fragment_content" android:layout_weight="7" android:layout_width="match_parent" android:layout_height="0dp"> <ImageView android:src="@drawable/phone_portrait_bg_02" android:layout_width="match_parent" android:layout_height="match_parent" android:scaleType="centerCrop"/> </FrameLayout> <fragment class="com.meralco.pms.ButtonsHandler" android:id="@+id/titles" android:layout_weight="1" android:layout_width="match_parent" android:layout_height="0dp" > <!-- Preview: layout=@layout/buttons --> </fragment> </LinearLayout> ``` ButtonsHandler.java ``` public class ButtonsHandler extends Fragment{ @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { // Inflate the layout for this fragment return inflater.inflate(R.layout.buttons, container, false); } } ``` buttons.xml ``` <?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent" android:gravity="center_horizontal|center_vertical"> <ImageButton android:id="@+id/button_sin" android:layout_weight="1" android:layout_width="0dp" android:layout_height="wrap_content" android:background="#000000" android:src="@drawable/button_sin" android:onClick="buttonClick" /> <ImageButton android:id="@+id/button_city" android:layout_weight="1" android:layout_width="0dp" android:layout_height="match_parent" android:background="#000000" android:src="@drawable/button_city" android:onClick="buttonClick" /> <ImageButton android:id="@+id/button_date" android:layout_weight="1" android:layout_width="0dp" android:layout_height="match_parent" android:background="#000000" android:src="@drawable/button_date" android:onClick="buttonClick" /> <ImageButton android:id="@+id/button_all" android:layout_weight="1" android:layout_width="0dp" android:layout_height="match_parent" android:background="#000000" android:src="@drawable/button_all" android:onClick="buttonClick" /> <ImageButton android:id="@+id/button_help" android:layout_weight="1" android:layout_width="0dp" android:layout_height="match_parent" android:background="#000000" android:src="@drawable/button_help" android:onClick="buttonClick" /> </LinearLayout> ``` TIA!