Using Java’s Documentation Comments
As explained in Part I, Java supports three types of comments. The first two are the // and the /* */. The third type is called a documentation comment. It begins with the character sequence /**. It ends with */. Documentation comments allow you to embed information about your program into the program itself. You can then use the javadoc utility program (supplied with the JDK) to extract the information and put it into an HTML file. Documentation comments make it convenient to document your programs. You have almost certainly seen documentation that uses such comments because that is the way the Java API library was documented. Beginning with JDK 9, javadoc includes support for modules.