public boolean returnLoan ( Loan loan ) { if ( loan != null ) { Book book = loan . getBook ( ) ; if ( book != null ) { String isbn = book . getIsbn ( ) ; if ( isbn != null ) { synchronized ( librarian ) { Integer quantity = isbns_to_quantities . get ( isbn ) ; if ( quantity != null ) { quantity = new Integer ( quantity . intValue ( ) + 1 ) ; isbns_to_quantities . put ( isbn , quantity ) ; return true ; } } } } } return false ; }
Return loan .