Java(TM) syntax supports three types of commenting, illustrated in the following table:

Comment Example	Description
int x; // a comment	Remainder of line beginning with "//" is a comment area
/* The variable x is an integer: */ int x;	All text between the "/*" and "*/", inclusive, is ignored by compiler
/** x -- an integer representing the x coordinate */ int x;	All text between the "/**" and "*/", inclusive, is ignored by compiler and intended for javadoc documentation utility

The javadoc documentation tool is quite powerful. The standard Java distribution from Sun includes documentation built with javadoc; hence, one avenue for learning this tool is to study the HTML documentation alongside the Java source code, which contains the comments that javadoc converts into HTML.