The string format, when added to string.xml resource, has a differente syntax, for exemple:
Hello, %s! You have %d new messages.
Becomes:
Hello, %1$s! You have %2$d new messages.
The syntax is: *%<position>$<type>*
. where <position>
starts at 1 and type
is the Java String format like d, s, f.
Source: String Resources