The rapid expansion of Java programs into software market is often not supported by a proper development methodology. Here, we present a formal development methodology well-suited for Java dependable distributed applications. It is based on the stepwise refinement of model-oriented formal spcifications, and enables validation of the obtained systme wrt the client's requirements. Three refinement steps have been identified in the case of fault-tolerant distributed applications: first, starting from informal requirements, an initial formal specification is derived. It does not depend on implementation constraints and provides a centralized solution; second, dependability and distribution constraints are integrated; third, the Java implementation is realised. The CO-OPN/2 language is used to express specifications formally; and the dependability and distribution design is based on the Coordinated Atomic action concept. The methodology and the three refinement steps are presented through a very simple fault-tolerant distributed Java application.