1. 注释符
a./ /单行注释符
b./* */多行注释符
c./** */文档注释符
2. 关键字（不能做标识符）
| abstract | byte | volatile | const | while |
| try | null | this | char | void |
| new | static | super | double | break |
| for | final | implements | false | protected |
| else | do | package | native | transient |
| extends | public | catch | int | interface |
| class | long | finally | switch | private |
| throws | case | goto | import | float |
| synchronized | instanceof | true | if | default |
| return | boolean | short | assent | enum |
3. 标识符
a.可由字母、下画线（-）、$、数字组成
b.大小写敏感
标签：false,synchronized,int,注释,关键字,标识符 From： https://www.cnblogs.com/-su-jis-jiao-zi-1/p/17281636.html