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The document says "@[+]id/myid" as the definition for android:id, from the notation it indicates that the plus is optional. But nowhere can I find a definition of what the plus sign means or not supplying it would mean.
What does it mean and why is it there?
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Save questions or answers and organize your favorite content. Learn more. Show activity on this post. The document says "@[+]id/myid" as the definition for android:id, from the notation it indicates that the plus is optional.
The definition of Android ID All smartphones and tablets are identified by a unique device ID. The Android unique device ID is called the Android Advertising ID (AAID).
The at-symbol (@) at the beginning of the string indicates that the XML parser should parse and expand the rest of the ID string and identify it as an ID resource. The plus-symbol (+) means that this is a new resource name that must be created and added to our resources (in the R. java file).
Android ID is an unique ID to each device. It is used to identify your device for market downloads, specific gaming applications that needs to identify your device (so that they know it's a device that was used to pay for the application) and such.
android:id. Resource ID. A unique resource name for the element, which you can use to obtain a reference to the ViewGroup from your application.
@+id/foo means you are creating an id named foo in the namespace of your application. You can refer to it using @id/foo. @android:id/foo means you are referring to an id defined in the android namespace. This namespace is the namespace of the framework. In this case, you need to use @android:id/list and @android:id/empty because these are the id the framework expects to find (the framework knows only about the ids in the android namespace.)
Taken from one of the "Android Developer | Google Groups" discussions.
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The documentation says,
The plus-symbol (+) means that this is a new resource name that must be created and added to our resources (in the R.java file). There are a number of other ID resources that are offered by the Android framework. When referencing an Android resource ID, you do not need the plus-symbol, but must add the android package namespace, like so:
android:id="@android:id/empty" If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
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