Your content must have a ListView whose id attribute is 'android.R.id.list'

I have created an xml file like this:

<?xml version="1.0" encoding="utf-8"?>
<ListView xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:id="@+id/list" >
</ListView>

and an activity:

public class ExampleActivity extends ListActivity {
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {   
        super.onCreate(savedInstanceState);
        setContentView(R.layout.mainlist);
    }
}

As you can see, I have not done anything else. But I'm getting this error:

Your content must have a ListView whose id attribute is 'android.R.id.list'

Even though I have the android:id="@+id/list" line in my xml.

What is the problem?

Rename the id of your ListView like this,

<ListView android:id="@android:id/list"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"/>

Since you are using ListActivity your xml file must specify the keyword android while mentioning to a ID.

If you need a custom ListView then instead of Extending a ListActivity, you have to simply extend an Activity and should have the same id without the keyword android.