Java Features
1, the object-oriented (write once, run anywhere)
2, cross-platform
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Java Architecture
JavaSE,JavaEE,JavaME,Java Card
Understanding of the JDK, JRE, JVM's
Write Java programs
Edit -> compile -> run
Identifier naming rules
1,26 case letters, numbers, underscores, dollar symbols
2, the numbers do not begin with
3, can not use java keywords, reserved words, special value (53)
4, strict case-sensitive
5, can not have spaces between
Identifier naming convention
1, see the name EENOW
2, class name, interface name: capitalize the first letter of each word
3, variable names, method names: uppercase first letter from the second
4, Package Name: All lowercase words
5. Constant name: All words capitalized, with underscores split between words
variable
The definition of variables, use requirements
Java data types
Basic data types (8 types), reference data types