The difference between @+id/and Android:id

Android:id= "@+id/btn" means a new control index with ID btn is added to the R.java file, the most common way to declare a control ID. Android:id= "@android: Id/tabhost", refers to the system's existing ID, in the corresponding SDK directory of ids.xml inside. The general external does not go to call, is the component internal call when used: android:id= "@id/btn", indicating that an existing ID is referenced, In R.java, for example, we have built a ids.xml, which declares a set of IDs, one of which is btn, so you can refer to this.

The difference between @+id/and Android:id