Views in a RelativeLayout with MapView are null

Question

I have a MapActivity with a mapview. It works fine. Now I want to add a SeekBar onto my MapView. It has to be at the bottom but on the mapview. User will scroll to set the distance. Whatever. My problem is, that any view I am trying to put there is null, when I reach them by findViewById().

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

    <com.google.android.maps.MapView
        xmlns:android="http://schemas.android.com/apk/res/android"
        android:id="@+id/mapview"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:clickable="true"
        android:apiKey="mykey"/>
    <SeekBar
        android:id="@+id/DistanceBar"
        android:max="2000"
        android:progress="2000"
        android:layout_alignParentBottom="true"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:padding="14dip"></SeekBar>
</RelativeLayout>

I am trying to reach that like this:

public class MyActivity extends MapActivity implements LocationListener {
...
SeekBar DistanceBar;
...
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    mapView = (MapView) findViewById(R.id.mapview);
    DistanceBar = (SeekBar) findViewById(R.id.DistanceBar); //This is afterwards null.

I have made a research everywhere and couldn't find a similar problem. Someone used something very similar. So I ignored that it is null, I didn't call the SeekBar in onCreate(). But the SeekBar hasn't been drawen at all. Can't I add other Views to a mapactivity?

Thanks for any idea!

An IMPORTANT EDIT: The graphical layout viewer shows the SeekBar as it should at the bottom of mapview.

I still get NullPointerException: ERROR/AndroidRuntime(12738): FATAL EXCEPTION: main

ERROR/AndroidRuntime(12738): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.MyApps.MapLocations/com.MyApps.MapLocations.MyActivity}: java.lang.NullPointerException

ERROR/AndroidRuntime(12738): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2663)

ERROR/AndroidRuntime(12738): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2679)

ERROR/AndroidRuntime(12738): at android.app.ActivityThread.access$2300(ActivityThread.java:125)

ERROR/AndroidRuntime(12738): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2033)

ERROR/AndroidRuntime(12738): at android.os.Handler.dispatchMessage(Handler.java:99)

ERROR/AndroidRuntime(12738): at android.os.Looper.loop(Looper.java:123)

ERROR/AndroidRuntime(12738): at android.app.ActivityThread.main(ActivityThread.java:4627)

ERROR/AndroidRuntime(12738): at java.lang.reflect.Method.invokeNative(Native Method)

ERROR/AndroidRuntime(12738): at java.lang.reflect.Method.invoke(Method.java:521)

ERROR/AndroidRuntime(12738): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:871)

ERROR/AndroidRuntime(12738): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:629)

ERROR/AndroidRuntime(12738): at dalvik.system.NativeStart.main(Native Method)

ERROR/AndroidRuntime(12738): Caused by: java.lang.NullPointerException

ERROR/AndroidRuntime(12738): at com.MyApps.MapLocations.MyActivity.setupSeekbar(MyActivity.java:343)

ERROR/AndroidRuntime(12738): at com.MyApps.MapLocations.MyActivity.onCreate(MyActivity.java:89)

ERROR/AndroidRuntime(12738): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)

ERROR/AndroidRuntime(12738): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2627)

ERROR/AndroidRuntime(12738): ... 11 more

Here is the result from HierarchyViewer:

Answer 1

I just have copied the main.xml file as map.xml and deleted main.xml. And it worked. I still don't understand why it happened. Maybe the "main" causes some problem. Maybe MapActivities have defined for themselves a "main" layout which is interrupting my "main" layout. But this was the solution somehow. Thanks a lot for your patience!

IMPORTANT EDIT: I have definitely found the problem. main.xml file remained in layout-normal and layout-normal-long folders without any SeekBar. I forgot to edit those.