What are the main projects in the company with those technologies in java?

java has a wide range of applications, most companies use ssh, ssi, javascript (jquery, extjs) and some other frameworks, some companies will also be packaged on the basis of some of their own things, to make their own framework.

java development is mainly bs, do the website (WAN, LAN) and things like that, the client program is relatively less.

Java is an object-oriented programming language that allows you to write cross-platform applications. java technology has excellent versatility, efficiency, platform portability and security, and is widely used in PCs, data centers, gaming consoles, scientific supercomputers, cell phones, and the Internet, as well as having the world's largest professional community of developers.

Java consists of four aspects:

The Java programming language, or syntax.

The Java file format, i.e., the suffixes of various folders and files.

The Java Virtual Machine (JVM), i.e., the interpreter that handles *.class files.

Java Application Programming Interface (Java API).