In this paper, a flow-sensitive, context-insensitive alias analysis in Java is proposed. It is more efficient and precise than previous analyses for C++, and it does not negatively affect the safety of aliased references. To this end, we first present a reference-set alias representation. Second, data-flow equations based on the propagation rules for the reference-set alias representation are introduced. The equations compute alias information more efficiently and precisely than previous analyses for C++. Third, for the constant time complexity of the type determination, a type table is introduced with reference variables and all possible types for each reference variable. Fourth, an alias analysis algorithm is proposed, which uses a popular iterative loop method for an alias analysis. Finally, running times of benchmark codes are compared for reference-set and existing object-pair representation.