Java learns from scratch (identifiers and keywords), starts from scratch and

Java learns from scratch (identifiers and keywords), starts from scratch and
Identifier, keyword, comment 1, identifier

The packages, classes, methods, parameters, and variable names in Java are composed of letters, numbers, underscores (_), and dollar signs ($) in any order,

Identifier: it cannot start with a number or be a reserved keyword in JAVA.

For example, yourname, yourname_dxh, li_yourname, and $ yourname are all valid identifiers.

Class, 67.9, Hello World is illegal, class is a keyword, 67.9 starts with a number, there is a space in the middle of Hello World

Ii. Keywords

Keywords in Java

 

Abstract	Boolean	Break	Byte	Case	Catch	Char
Class	Continue	Default	Do	Double	Else	Extends
False	Final	Finally	Float	For	If	Implements
Import	Instanceof	Int	Interface	Long	Native	New
Null	Package	Private	Protected	Public	Return	Short
Static	Synchronized	Super	This	Throw	Throws	Transient
True	Try	Void	Volatile	While	Assert	Enum

 

3. Notes

• Single line comment:

// Indicates a single line comment. The comment content is here, and a line is commented. Add a double slash before the content to be commented (//)

• Multi-line comment:

/** Multi-line comment, starting with a single slash plus a star (/*), ending with a star plus a single slash */

• Document comment

 

/*** Document comments * start with a single slash plus two star tags (/**), and add a slash to a star tag (*/) at the end of * The content annotated with this method will be interpreted as a formal document of the program and can be included in the document generated by a tool such as javadoc */