Building Java applets by using DJ-a Java-based constraint language

DJ (Declarative Java) is an extension of Java that supports constraint programming. On the one hand, DJ can serve as a high-level specification language for Java applets. To construct a graphic user interface (GUI) with DJ, the users only need to specify the components that compose the GUI and the relationships among the components by using constraints. On the other hand, DJ, as a constraint language, improves the current constraint languages in that problems and solutions can be described in the same language. In addition, since DJ is a compiling language that uses Java as the object language for compilation, solutions can be distributed on the WWW as Java applets. We present DJ by examples, aiming at illustrating the power and programming methodology of DJ.