question: public MailInAdapterResult findMail ( Mail mail ) { int indexPosition = Collections . binarySearch ( items , mail , MailComparator . INSTANCE ) ; boolean containsMail = false ; Mail found = null ; if ( indexPosition < 0 ) { indexPosition = ~ indexPosition ; } else { found = items . get ( indexPosition ) ; if ( found . getId ( ) == mail . getId ( ) ) { containsMail = true ; } else { containsMail = false ; found = null ; } } return new MailInAdapterResult ( containsMail , found , indexPosition ) ; }
target:  Searches for an equal mail (compares mail id) in the adapter.