Upendra 
@id vs @+id
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). In other words, the + symbol tells Android build tools that you are declaring a new resource, @id/ you are referring to an existing resource (predefined by @+id/ and already exists in R.java.