Android Studio ile "hello world" nasıl yazılır?

package com.dnm;

import android.app.Activity;
import android.os.Bundle;

public class MainActivity extends Activity {

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

}

<resources>
   <string name="app_name">HelloWorld</string>
   <string name="hello_world">Hello world!</string>
</resources>

<TextView
        android:id="@+id/textView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Hello World" />

// in onCreate method
TextView textView = new TextView(this);
textView.setText("Hello World");

setContentView(textView);