How to define variables in java

In java, variables can be defined through the statement "data type identifier;" or "data type identifier = initialization value;"; the identifier is also called the variable name, which consists of numbers (0~9) , uppercase and lowercase letters, underscores, dollar signs ($), RMB signs (¥), and all ASCII codes before hexadecimal 0xc0.

The operating environment of this tutorial: windows7 system, java8 version, DELL G3 computer.

Define/Declare variables

For developers, variables are aliases used to describe a piece of information. One or more variables can be used in program code. Various types of information can be stored in variables, such as login information, version name, file size, a certain English word, and flight ticket price.

In Java, users can declare variables by specifying data types and identifiers. The basic syntax is as follows:

DataType identifier;

or

DataType identifier=value;

The above syntax code involves 3 Each content: DataType, identifier and value, the specific description is as follows:

• DataType: variable type, such as int, string, char and double, etc.

• identifier: identifier, also called variable name.

• value: The value when the variable is declared.

The naming convention for variable identifiers is as follows:

• The first character must be a letter, underscore (-), dollar symbol ($) or RMB symbol (¥).

• The identifier consists of numbers (0~9), uppercase letters (A~Z), lowercase letters (a~z), underscore (-), dollar sign ($), RMB symbol (¥) and all ASCII codes before hexadecimal 0xc0.

• Keywords and reserved words cannot be used as identifiers.

• There is no limit on the length of identifiers.

• Identifiers are case-sensitive.

The following code declares variables of type String, boolean and int respectively.

String employee;    // String 类型的变量
boolean isSave;    // boolean 类型的变量
int create_at;    // int 类型的变量

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