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..

could you post your reference code(JAVA)?

code-jaff
– code-jaff

2012-08-03 08:35:40 +00:00
Commented Aug 3, 2012 at 8:35 — code-jaff
– code-jaff, Commented Aug 3, 2012 at 8:35

Maragues · Accepted Answer · 2012-08-03 08:43:57Z

11

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

answered Aug 3, 2012 at 8:43

Maragues

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2 Comments

Maragues Over a year ago

ADT plugin sometime fails... I also went crazy when this first happened to me

Garnet Ulrich Over a year ago

Son of a gun. Fixed the problem. Thank you.

KarlchenKanther · Accepted Answer · 2012-10-31 12:10:32Z

1

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.

answered Oct 31, 2012 at 12:10

KarlchenKanther

814 bronze badges

Comments

Franky · Accepted Answer · 2020-08-18 06:27:15Z

To be further extensive for all of those that may have also missed something obvious in their code (as I did):

Make sure that your java code doesn't literally cast your layout as a button:

public class MainActivity extends AppCompatActivity {
    protected Button LL_vertical; //MISTAKE HERE


    public void someFunction() {

        //R.id.LL_vertical is a linearlayout
        LL_vertical = view.findViewById(R.id.LL_vertical); 

        ...

    }

 ... rest of code ..
}

should be

public class MainActivity extends AppCompatActivity {
    protected LinearLayout LL_vertical; //MISTAKE FIXED

    public void someFunction() {

        //R.id.LL_vertical is a linearlayout
        LL_vertical = view.findViewById(R.id.LL_vertical); 
        
        ...

    }

 ... rest of code ..
}

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