Android - trouble with R class

I am trying to code some basic stuff (listView and the like) in Android. My problem is as follows:

1. Any resource that I write (eg. an xml file specifying the content of a listView or a button), gets registered in the R class but eclipse flags it as an error when I try to use it.

Example:

Relative Layout xml file:

<?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">

  <ListView android:id="@android:id/android开发者_如何学运维:list"
     android:textFilterEnabled="true"
     android:layout_width="fill_parent"
     android:layout_height="wrap_content"
     android:layout_weight="1"
     android:dividerHeight="3dp"
  />

  <TextView android:id="@+id/simpleText"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:padding="10dp"
    android:textSize="16sp" >
</TextView>

  <Button android:id="@+id/nextButton"
     android:text="@string/next"
     android:layout_height="wrap_content"
     android:layout_width="wrap_content"
     android:layout_alignParentBottom="true"
     android:layout_centerHorizontal="true"
     android:layout_centerVertical="true"
  />

</RelativeLayout>  

Code is as follows:

public class sample extends ListActivity {
    /** Called when the activity is first created. */

    private Button nxtButton;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        Log.v(this.toString(), "Inside the function.");

        nxtButton = (Button)findViewById(R.id.nextButton);
        nxtButton.setOnClickListener(new View.OnClickListener() {   
            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub
                //This method is to change to the next screen.
                Log.v(this.toString(), "The next button has been clicked. Taking you to the next screen.");             
            }
        });

        }
}  

R.java looks like so:

public final class R {
    public static final class attr {
    }
    public static final class drawable {
        public static final int icon=0x7f020000;
    }
    public static final class id {
        public static final int nextButton=0x7f050001;
        public static final int simpleText=0x7f050000;
    }
    public static final class layout {
        public static final int relLayout=0x7f030000;
        public static final int list_item=0x7f030001;
        public static final int main=0x7f030002;
    }
    public static final class string {
        public static final int app_name=0x7f040001;
        public static final int hello=0x7f040000;
        public static final int nextButton=0x7f040002;
    }
}  

My problem is as follows:

1. Even though the next button is registered in R.java, I get an error every time I try to do a findViewById on any resource that I have defined. Building the project also does not yield any results.

The error I get is: nextButton cannot be resolved or is not a field

I have come across a few questions on SO on these lines, but none whose solutions I have been able to use successfully.

You should ensure you've imported your R java class, not android.R.

Remove any false R imports at the top of your Java classes. If that is not the problem, delete your R file and refresh the project (right-click -> refresh).