Dynamic vs XML layout in Android?

I'm new to Android development and have started creating my own UI. I see that you can either create it dynamically something like this (Dynamic Layouts):

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    ScrollView sv = new ScrollView(this);
    LinearLayout ll = new LinearLayout(this);
    ll.setOrientation(LinearLayout.VERTICAL);
    sv.addView(ll);
    TextView tv = new TextView(this);
    tv.setText("Name");
    ll.addView(tv);
    EditText et = new EditText(this);
    ll.addView(et);
    Button b = new Button(this);
    b.setText("Ok");
    ll.addView(b);
}

but I also see that netbeans has a file Resources->layout->main.xml. So you can create an XML layout for the UI (Declaring XML layout):

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    >
<TextView  
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content" 
    android:text="Hello World, AndroidTest"
    />
</LinearLayout>

So my question is which should I use? what is recommended and what are the pros/cons of dynamic vs XML layouts in Android development?