Question

I am having a very weird exception!. First I reference to a Relative layout, then i try to get its visibility state, but the activity crashes and throws a NullPointerException at getVisibilty();
I Have no idea why!, I spent a lot of time trying to figure out the problem but I couldn’t!,Here is my Activity code:

    setContentView(R.layout.main3d_activity);
    RelativeLayout optionLayout;
    optionLayout = (RelativeLayout) findViewById(R.id.main_optionLayout);
    int vis= optionLayout.getVisibility();

main3d_activity code:

    <?xml version="1.0" encoding="utf-8"?> 
    <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/MainLayout"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >

    <include
        android:id="@+id/include_headerbar"
        android:layout_width="fill_parent"
        android:layout_height="60dp"
        layout="@layout/headerbar_layout" />
    <include
        android:id="@+id/include_footerbar"
        android:layout_width="fill_parent"
        android:layout_height="60dp"
        android:layout_alignParentBottom="true"
        layout="@layout/footerbar_layout" />

    <ViewFlipper
        android:id="@+id/vf"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_above="@+id/include_footerbar"
        android:layout_below="@+id/include_headerbar" >

        <include
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            layout="@layout/container_mainlayout" />

        <include
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            layout="@layout/living_layout" />

        <include
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            layout="@layout/bedroom_layout" />

        <include
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            layout="@layout/childrenbedroom_layout" />

        <include
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            layout="@layout/kitchen_layout" />

        <include
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            layout="@layout/dinningroom_layout" />

        <include
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            layout="@layout/corridor_layout" />

        <include
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            layout="@layout/roof_layout" />

        <include
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            layout="@layout/garden_layout" />

        <include
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            layout="@layout/garage_layout" />

        <include
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            layout="@layout/container_mainlayout" />
    </ViewFlipper>

    <include
        android:layout_width="300dp"
        android:layout_height="match_parent"
        android:layout_above="@+id/include_footerbar"
        android:layout_alignParentRight="true"
        android:layout_below="@+id/include_headerbar"
        layout="@layout/slidingdrawer_infolayout" />

    <include
        android:layout_width="300dp"
        android:layout_height="400dp"
        android:layout_alignParentBottom="true"
        android:layout_centerHorizontal="true"
        layout="@layout/slidingdrawer_roomslistlayout" />

    <include
        android:layout_width="350dp"
        android:layout_height="300dp"
        android:layout_above="@+id/include_footerbar"
        android:layout_alignParentRight="true"
        layout="@layout/logger_layout" />

    <include
        android:id="@+id/include_relativeMenu"
        android:layout_width="200dp"
        android:layout_height="wrap_content"
        android:layout_alignParentRight="true"
        android:layout_below="@+id/include_headerbar"
        layout="@layout/options_menulayout" />

</RelativeLayout>

options_menuLayout xml code:

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/main_optionLayout"
android:layout_width="200dp"
android:layout_height="wrap_content"
android:layout_alignParentRight="true"
android:background="@drawable/main_headerbackground"
android:orientation="vertical"
android:visibility="invisible" >

<Button
    android:id="@+id/relativeMenuAllSensorsButton"
    android:layout_width="200dp"
    android:layout_height="50dp"
    android:layout_alignParentTop="true"
    android:background="@drawable/main_headerbackground"
    android:gravity="center_vertical|center_horizontal"
    android:text="Activation List"
    android:textColor="@android:color/white"
    android:textSize="18sp" />

<Button
    android:id="@+id/relativeMenuUsersButton"
    android:layout_width="200dp"
    android:layout_height="50dp"
    android:layout_below="@+id/relativeMenuAllSensorsButton"
    android:background="@drawable/main_headerbackground"
    android:gravity="center_vertical|center_horizontal"
    android:text="Users"
    android:textColor="@android:color/white"
    android:textSize="18sp" />

<Button
    android:id="@+id/relativeMenuPreferencesButton"
    android:layout_width="200dp"
    android:layout_height="50dp"
    android:layout_below="@+id/relativeMenuUsersButton"
    android:background="@drawable/main_headerbackground"
    android:gravity="center_vertical|center_horizontal"
    android:text="Settings"
    android:textColor="@android:color/white"
    android:textSize="18sp" />

I tried cleaning the project, rebuilding the workspace and even using different emulator but the same problem persists!

Answer 1

In main3d_activity.xml you have:

<include
    android:id="@+id/include_relativeMenu"
    android:layout_width="200dp"
    android:layout_height="wrap_content"
    android:layout_alignParentRight="true"
     android:layout_below="@+id/include_headerbar"
    layout="@layout/options_menulayout" />

And then in options_menulayout.xml you have:

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/main_optionLayout"

So it looks like you’re overriding the id when you include it. Remove

    android:id="@+id/include_relativeMenu"

from the include, or search for that ID rather than the other one.