public static String readLine ( ) throws IOException {
  st = null ;
  return br . readLine ( ) ;
}

public static String readLine ( ) throws IOException { st = null ; return br . readLine ( ) ; }
(method_declaration (modifiers) type: (type_identifier) name: (identifier) parameters: (formal_parameters) (throws (type_identifier)) body: (block (expression_statement (assignment_expression left: (identifier) right: (null_literal))) (return_statement (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)))))