Abstract: Data flow anomalies（DFA） are those anomalies related to the accessing and updating of data items in a program. The conventional DFA detection techniques alone can not be used to identify the data flow anomalies associated with the instance variables defined in a class. In this paper, a method for identifying the data flow anomalies present across the methods of a class is proposed. The method sequence specification（MtSS） is used in conjunction with the conventional DFA detection techniques to identify the data flow anomalies in classes. This technique can ensure that there are no data flow anomalies present across methods in a class if the methods are invoked in such a way that they are compliant with the method sequence specification.