Activity Layout: Fragment class: vs android:name attributes

Gianni Costanzi picture Gianni Costanzi · Apr 15, 2012 · Viewed 20.8k times · Source

I've read the documentation about Fragments in the Android Developer Guide and I've seen that sometimes they specify the class to instantiate with the Fragment tag attribute android:name and sometime they use the class: attribute:

<fragment
    android:name="com.example.news.ArticleReaderFragment"
    android:id="@+id/viewer"
    android:layout_weight="2"
    android:layout_width="0dp"
    android:layout_height="match_parent" />

<fragment
    class="com.example.android.apis.app.FragmentLayout$TitlesFragment"
    android:id="@+id/titles" 
    android:layout_weight="1"
    android:layout_width="0px" 
    android:layout_height="match_parent" />

Are android:name and class: interchangeable? If I use the autocompletion function in Eclipse, they both show the same documentation tip (i.e. the attribute provides the class name to be instantiated). Maybe you must use the second one when the class to be instantiated has a name which is different from the java file name, like TitlesFragment which is in the FragmentLayout.java file? Or can I use the syntax package.fileDOTjava$Class also with the android:name attribute?

I'd like to have some documentation for XML tags and attributes as for Android Java Classes (I've asked about it in another question).

Answer

far.be picture far.be · Dec 19, 2012

As Activity.onCreateView source says:

String fname = attrs.getAttributeValue(null, "class");
TypedArray a = context.obtainStyledAttributes(attrs, com.android.internal.R.styleable.Fragment);
if (fname == null) {
    fname = a.getString(com.android.internal.R.styleable.Fragment_name);
}

That seemingly means that program looks "class" attribute first. And on fail looks "name" attribute. So as far as it's true using "class" if more efficient.