How are Java variables declared?

In Java, you can use keywords to declare variables. Declarations typically include the type and name of the variable.

Syntax format:

数据类型 变量名;

In this case, the data type can be either a primitive data type provided by Java, such as int, double, boolean, etc., or a custom class type.

For example, we can define an integer variable.

int num;

Declare a string variable:

String name;

You can also assign an initial value to a variable when defining it.

int age = 18;
String message = "Hello World!";

When defining a variable, you can also use the keyword “final” to modify the variable, indicating that the value of the variable cannot be changed once it is assigned, making it a constant.

final double PI = 3.14;