Key features:
1, completely lowercase letters
2, the software is a special color
Identifier:
All components of the Java name is required. Class names, method names and variable names are called tags.
- All identifier can not begin with a number
- After the first character may be a letter (AZ or az), any combination of characters dollar sign ($), underscore (_) or digital
- Keywords can not be used as an identifier
- Identifiers are case sensitive
- Legal identifier, for example: age, $ salary, _value, __ 1_value
- Illegal identifier example: 123abc, -salary