Difference between “@id/” and “@+id/” in Android

Question

What is the diffirence between the @id/ and @+id/?

In @+id/ the plus symbol

Answer 1

If the view item performs the same operation, you can use the @+id for each entry in any layout because during the compilation of multiple @+id/foo the R.java file only creates one enumeration. So for example, if I have a save button on each page that performs the same operation, I use android:id="@+id/button_save" in each layout. The R.java file only has one entry for the button_save.