JRE extension and jar files and documentation generator

1.JRE jar file extensions and
apparently java runtime environment provided by the library does not meet all our needs, so it must be extended, the path is \ jre \ lib \ ext we just write your own class packaged as jar file format ext put in, we can use with the import statement.
Demo Link: https: //www.cnblogs.com/blog5277/p/5920560.html

2. Document Generator
javadoc.exe JDK provided can make html document source file class structure, we can see the composition of the structure of these files in the documentation for the class.
Demo Link: https: //www.cnblogs.com/toutou/p/javadoc.html