Dynamic Strings and Xml

I'm new to Android (and surely I'm not an expert Java developer), so I'm sorry for the dumb question

I would like to "capture" the id of a textView and to set its text value dynamically, here is how I'm trying to do this:

public class AndStringTestActivity extends Activity {
/** Called when the activity is first created. */

String abc = "abcabc";

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

    TextView tv = (TextView)findViewById(R.id.test);
    tv.setText(abc);

    setContentView(R.layout.main);
}
}

and here is the Xml from which i'm reading the id of the textview i would like to write inside

// main.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android开发者_如何学Python="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
>
<TextView  
android:id="@+id/test"
android:layout_width="fill_parent"
android:layout_height="fill_parent"    
/> 
</LinearLayout>

the error i receive is the usual Application stopped unexpectedly

Thanks.

Call setContentView before trying to find the TextView. The TextView does not exist before you have called setContentView (which will inflate your XML layout)

Call setContentView(R.layout.main) before you call findViewById().