* All dry goods
type of data:
java is a strongly typed language, each variable must declare its data type, then the java data types as the basic data types and application data types. java third base defined eight basic data types:
數值型：整數型（byte, short, int, long）,浮點型（ float, double）.
字符型：char.
布而類型：boolean.
以上為基本的數據類型
引用數據類型分為：
類（class)
接口（interface）
**
## operators:
arithmetic operators (+, -, *, /,%)
assignment operator (=, + =, - =, * = /% ,, = =)
relational operators (>,> =, ! <, <=, =)
conditional operator (&&, ||, &, | !, ^)
bitwise operators (&, |, ^, ~ , >>, <<, <<<, >>>)
The following reference topics for study:
bytes 1 java basic data type corresponding to?
Basic types of accounting memory (1 byte is 8 bits) indicates the range of
byte 1 byte to 127 -128: -1 -2 7 th to 7-th power of 2
Short -32768 to 32767 bytes 2: -2 the 15 th to the 15 th power of 2 -1
31 31 -1 -2 th power to 2: int 4 bytes -2147483648 2147483647
63 -2 63 bytes long 8-th power to 2 Party -1
a float. 4 byte valid bits fractional bits 6-7
double 8-bit byte valid decimal 15
char 2 bytes
boolean 1 byte
What JAVA identifier: the
terms through the element, the identifier is used to variables, classes, methods, and naming package.
Such as:. Welcome, Class, System, age, etc
but it must be a letter, underscore _ a dollar sign, $, can not be a keyword.
Stressed: not recommended Chinese