JTN is a formal graphic notation for Java-targeted design speci cations, that are speci cations of systems that will be implemented using Java. JTN is aimed to be a part of a more articulated project for the production of a development method for reactive/concurrent/distributed systems. The starting point of this project is an existing general method that however does not cover the coding phase of the development process. Such approach provides formal graphic speci cations for the system hat are too abstract to be transformed into Java code in just one step, or at least, the transformation is really hard and complex. We introduce in the development process an intermediate step that transe above abstract speci cations into JTN speci cations, for which the transformation into a Java program is almost automatic and can be guaranteed correct. In this paper we present JTN on a simple toy example.