Understand the R class in Android
I cant understand why use 'R' Class in android application.
Can explain why use R used here.
Your question is duplicate of Understand the R class in Android
When your application is compiled, aapt generates the R class, which contains resource IDs for all the resources in your res/ directory. For each type of resource, there is an R subclass (for example, R.drawable for all drawable resources) and for each resource of that type, there is a static integer (for example, R.drawable.icon). This integer is the resource ID that you can use to retrieve your resource.
I got this detail from the below link ,check this once for more details : http://developer.android.com/guide/topics/resources/accessing-resources.html
R.java which is Automatically System generated file it contains the id of each resources used in Application which is used to make refrence.
R.class contains IDs for all your android resources.
You can find more info here: http://developer.android.com/reference/android/R.html
R.class holds reference for all your android resources.. without which you cannot access any resources (drawable, layout, xmls etc) And R.class is Autogenerated.
R is the class that contains all the resource ids for your application.
Its a resource class, contains ID for for all resources. Here you can also use