java variables, strings, arrays, operators

variable

Variable naming convention

The word art cannot begin, and the rest can include numbers, letters, underscores, and $ signs;

Variable type

Basic data types: four types and eight (values ​​are stored)
reference data types: class, array, enumeration, (address values ​​are stored)

Eight basic data types

Variable definitions

Variable type variable name=variable value;
long integer: you can add lowercase l or uppercase L after the variable value, further explanation is long integer
float: must be the lowercase f or uppercase F after the variable value, indicating that it is a float type , Otherwise the system considers it to be a double type and prompts an error

//定义变量
		//数据类型  变量名=值；
		boolean boll1=true