Question

When I using XML to design layout, I am using findViewById() in java code to load views and set listeners to them.

Is this correct what I am doing? May be it is possible to set listeners in XML or something?

Answer 1

Most people set their listeners in code. It’s sometimes easier to do it in code because you often times will need to add or remove listeners based on some action or state.

However, Android also gives you the option of setting a OnClickListener for any View in XML. Here’s an example:

<Button
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:onClick="onActionClick"
    android:text="Action" />

Using the onClick attribute, you assign the name of the method that will handle the click. This method must exist in the same Context as the View, so in the same Activity. So for example, I would have to implement this method:

public void onActionClick(View v) {

    // Do stuff for my "Action" button...
}

I believe it has to have a View parameter, just like implementing OnClickListener would. I also believe it must be public.

So as far as which way is “best”? That’s up to you. Both routes are viable. It’s worth noting though that this is only useful for click listeners and not other types of listeners.