Android: "@+id/" and "@+id/"

Issue

According to this thread I need to use @+id/ for the first time to make resource be created.

But what if I forget that this resource was previously created and create it again with @+id/? I have some input and set nextFocusDown for the element that is still not declared.

<EditText 
...
android:nextFocusDown="@+id/myinput2"/>

200 lines below I create this element with @+id because I forgot that it's already declared.

<EditText 
...
android:id="@+id/myinput2"/>

It works like this but can it cause an issue?

Solution

Some quick definitions:

• @+id/foo means "use the id foo, and create it if it doesn't exist"
• @id/foo means "use the id foo" (which will be an error if the id foo doesn't exist)

Previously, there were reasons to prefer @id over @+id (the system could tell you if you tried to reference a view via an id that didn't exist), but now the system is smart enough that even writing android:layout_below="@+id/idthatdoesntexistanywhere" will be tagged as an error:

So just always use @+id.

Answered By - Ben P.