Older Dick Silk Self-study note--java 0 basics to rookie--005

keywords, identifiers, comments, constants

1. Key words

The Java language has a specific meaning of the word, the letters are all lowercase, such as: class, public, static, void ...

2. Identifiers

Names of interfaces, classes, methods, variables, such as Fin, main ...

Composition rules: English letters, Numbers, $, _ ...

Note: Cannot start with a number, cannot use keywords, English letters are case-sensitive

Naming rules: Package: Lowercase letters, multi-level package between the subordinate ".", such as: Liverpool (single-stage package), Liverpool.gerrard (multi-level package) ...

Interface: Uppercase "I" with the first letter of each word capitalized, such as: Ifin, Iliverpoolgerrard ...

Class: Capitalize the first letter of each word, such as: Fin, Liverpoolgerrard ...

　　　　　Method: First letter lowercase, the remaining words capitalized, such as: Main, Liverpoolgerrard ...

Variables: First letter lowercase, the remaining words capitalized, such as: Liverpool, Liverpoolgerrard ...

Constants: All letters are capitalized, and words are separated by "_", such as: LIVERPOOL, Liverpool_gerrard ...

3. Comments

Single-line Comment://

Multiline Comment:/* ... */

Documentation Notes:/** ... */

4. Constants

The amount of value does not change during program execution.

String constants: "Liverpool"

Character constant: ' n '

Integer constants: 1892

Decimal constants: 3.14

Boolean constant: True, False

NULL constant: null

Older Dick Silk Self-study note--java 0 basics to rookie--005