The rapid expansion of Java programs into the software market is often not supported by a proper development methodology. We present a formal development methodology, well suited for Java dependable distributed applications. It is based on the stepwise refinement of model oriented formal specifications, and enables validation of the obtained system 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 as 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.