issue with “@id” vs “@+id” in positioning in Relative Layout

Question

Good day, i have a slight issue with relative layouts and i don\'t know why. Normally when you trying to position relative to other views, you use \"@id\" but it doesn\'t se

Answer 1

After experimenting with ConstraintLayout, check the snippet of code below, both views are wrapped in constraintLayout, i'll just paste the case code:

the line:

 app:layout_constraintTop_toBottomOf="@id/progress"

displays the textview pinned to the top of the view window in the editor, everything look fine in runtime but still this was confusing, now if you write it this way

 app:layout_constraintTop_toBottomOf="@+id/progress"

displays textview below the progress in UI editor as expected, reading through kcoppock explanation i find it matching the case.