LinearLayout cannot be cast to android.widget.Button

Question

My original layout xml file looks like this:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/app"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_margin="0px"
android:background="#e4e8ed"
android:orientation="vertical"
android:padding="0px" >

<include
    android:id="@+id/tabBar"
    layout="@layout/tab" />


<Button
    android:id="@+id/nist"
    android:layout_width="301dp"
    android:layout_height="63dp"
    android:text="Generate NIST file" />

<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/rectangle"
    android:layout_width="276dp"
    android:layout_height="wrap_content"
    android:background="@drawable/rectangle"
    android:layout_gravity="center_horizontal">

    <ToggleButton
        android:id="@+id/toggleButton1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="ToggleButton" />

    <Button
        android:id="@+id/button1"
        android:layout_width="wrap_content"
        android:layout_height="128dp"
        android:text="Button" />

</LinearLayout>

</LinearLayout>

But if I move the Button beneath the inner LinearLayout my app is just throwing an exception:

LinearLayout cannot be cast to android.widget.Button 

I think this is weird, how can I manage to do so?

EDIT:

This is the way I "import" the button to my java code:

setTabBar(R.layout.horz_scroll_app);
nist = (Button) findViewById(R.id.nist);

The setTabBar method:

public void setTabBar(int id) {

    LayoutInflater inflater = LayoutInflater.from(this);
    scrollView = (MyHorizontalScrollView) inflater.inflate(
            R.layout.horz_scroll_with_list_menu, null);
    setContentView(scrollView);

    menu = inflater.inflate(R.layout.horz_scroll_menu, null);

    app = inflater.inflate(id, null);
    ViewGroup tabBar = (ViewGroup) app.findViewById(R.id.tabBar);

    ListView listView = (ListView) app.findViewById(R.id.list);

    listView = (ListView) menu.findViewById(R.id.list);

    ArrayList<MenuItem> menuItems = getMenuItems();
    listView.setAdapter(new MenuCustomAdapter(this, menuItems));

    btnSlide = (ImageButton) tabBar.findViewById(R.id.BtnSlide);
    btnSlide.setOnTouchListener(new OnTouchListener() {

        @Override
        public boolean onTouch(View v, MotionEvent event) {

            switch (event.getAction()) {

            case MotionEvent.ACTION_DOWN:
                btnSlide.setImageResource(R.drawable.lincolor);
                break;
            case MotionEvent.ACTION_UP:
                btnSlide.setImageResource(R.drawable.lin);
                break;
            }

            return false;
        }

    });
    btnSlide.setOnClickListener(new ClickListenerForScrolling(scrollView,
            menu));

    final View[] children = new View[] { menu, app };

    int scrollToViewIdx = 1;
    scrollView.initViews(children, scrollToViewIdx,
            new SizeCallbackForMenu(btnSlide));

}

I should also mention that this problem occurs ONLY for the Button element if I add other elements under the inner LinearLayout it works..

Answer 1

Try cleaning and rebuilding the project, or restart Eclipse if that doesn't work.

Answer 2

Experienced the same problem, what helped me out:

Make sure you do not use the default ID for your view-element (togglebutton, editText, etc).

When you add and remove new elements of the same type in your layout they seem to disturb each other.

So, always use an individual ID.