Java syntax base identifiers and keywords

First, identifiers

The variable names, method names, class names, and object names in Java are identifiers, and the program requires identifiers to be uniquely identified in the process of writing the program. The naming rules for identifiers in Java are as follows:

• Can consist of uppercase and lowercase letters, numbers, underscores, and dollar signs in any order.

• Cannot start with a number.

• cannot be a reserved keyword in java.

• There are no length restrictions, but case sensitivity, such as Hello and hello are different identifiers.

Second, the key word

Like other languages, there are many reserved keywords in Java (that is, special meaning in Java), such as public, break, and so on, which cannot be used as identifiers. We don't need to memorize any of the keywords and know that this is enough, and if you accidentally use these keywords, the compiler can tell us the error. The Java keyword is shown in the following table:

Abstract	Boolean	Break	Byte	Case	Catch
Char	Class	Continue	Default	Do	Double
Else	Extend	False	Final	Finally	Float
For	If	Implement	Import	instanceof	Int
Interface	Long	Native	New	Null	Package
Private	Protected	Public	Return	Short	Static
Super	Switch	Synchronized	This	Throw	Throws
Transient	True	Try	void	Volatile	Ehile
Goto	Const

Note : Gogo, const, and so on are no longer used in the Java language, but you cannot use Goto or const as the variable name.

III. naming conventions for Java identifiers

From the Java language syntax, the name is very arbitrary, but in our daily programming process, in order to improve the readability of the code, maintainability and convenient debugging, the name of the best "see", correctly use the case, and follow the following rules:

Package name: In lowercase English words, preferably have a hierarchy, such as: Com.hq.core.

Class name and interface name: usually nouns, denoted by one or several English words, with the first letter of each word capitalized, for example: Color, FileInputStream.

Method name: Usually a verb, the first letter is lowercase, and if there are other words, start with the first letter capitalized from the second word, such as: Main (), Draw (), SetColor ().

Variable name or object name: Same as method casing rules.

Constant name: declared as public static final, all uppercase letters, words and words separated by underscores, such as: Max_value.

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Java syntax base identifiers and keywords