(Java syntax format, keyword, identifier, comment, data type, constant and variable, variable effect field, data type conversion, operator, expression. Program process control sentences and their usage scenarios, overloading of functions and functions, arrays and common operations. Goal oriented thinking, an overview of classes, the nature of goals, the relationship between classes and goals, and how to use goal oriented thinking to solve problems in practical development. How to design classes, the basic principles of designing classes, and the use of goals. Java call system structure, exception, IO concept, concept of multithreading, Java graphical user interface programming (AWT, Swing), Java network programming, network communication model, three elements of network communication, and their corresponding Java implementations. Java's high-end features: classloader,)