What is better android.R or custom R?

When I started developping android applications, I had a tendency to define custom R values wherever I need, in particular in layout files. For instance:

findViewById(R.id.customerName).setText(customer.getName())

with layout:

<TextView android:text="TextView" android:id="@id/customerName"
    android:layout_height="wrap_content" android:layout_width="fill_parent" />

Now I realize, it might be better to use android.R instead.

findViewById(android.R.id.text1).setText(customer.getName())

with layout:

<TextView android:text="TextView" android:id="@android:id/text1"
    android:layout_height="wrap_content" android:layout_width="fill_parent" />

What practice do you follow? What are the advantages and disadvantages of each?

Solution

There is no big advantage or disadvantage of the framework id vs the custom id in layouts.

Advantages of using framework identifiers:

Avoid the creation of more identifiers. Saves one field in the apk (and there is an apk size limit).
Must be used in some situations, like ListActivity

Drawbacks of using framework identifiers:

Don't provide a descriptive name

In both practices

The code will work in the future
Missing references are discovered at runtime, and hidden at compile time

I thought the the samples in the SDK would help me take a decision, and (guess what?) it doesn't. The Notepad and LunarLander applications use the android.R.id for the view identifiers, whereas the ApiDemos project uses custom identifiers.

Best practice for GestureBuilder which mixes both approaches? (@+id/addButton and @android:id/empty)

IHMO, worse practice for HelloActivity and JetBoy which define @+id/text @+id/Button01... This is not descriptive and could have been replaced by (@andoid:id/button1, or by @+id/startButton)