The first stage:. Java foundation 1.JAVA Development Introduction --- 5 Java comments, identifiers, identifier naming convention

1.java comments

　　There are three ways java comment, single-line comments, multiline comments, the document notes.

　　. (1) single-line comments:shortcut Ctrl + / revoked again by the comment,

　　. (2) multi-line comments: Ctrl + shift + / Undo Ctrl + shift + \

　　. (3) Documentation Comments: shift + alt + j

2. Identifier

　　(1) An identifier of English character case 26 (a ~ zA ~ Z), numbers (0 to 9), underscore (_) and the dollar sign ($) composition.

　　(2) You can not start with a number, not a keyword

　　(3) strictly case-sensitive

　　(4) The identifier may be any length