Outlines the concepts and methodology for developing object-oriented programs in C++ CLI, C #, and Java (J #). The presentation is accompanied by numerous examples of completed programs. The programs are explained by UML diagrams. Particular attention is paid to the most difficult to understand delegates, events, notifications, flows and their synchronization. A parallel presentation of similar basic language constructs will better reveal not only the proximity and difference between C++ CLI, C # and Java, but also better understand the features of these languages.