static final

static final is a keyword used in the Java programming language to define a constant variable that cannot be changed once it has been assigned a value. When a variable is declared as static final

it means that it belongs to the class itself rather than an instance of the class

and its value remains the same for all instances of the class.

The static keyword means that the variable is associated with the class itself rather than an instance of the class. This means that the variable is shared among all instances of the class and can be accessed without creating an object of the class. This is useful for defining constants or variables that need to be shared among multiple instances of the class.

The final keyword means that the value of the variable cannot be changed once it has been assigned a value. This ensures that the variable remains constant throughout the execution of the program and prevents accidental changes to its value. When a variable is declared as final

it must be initialized with a value at the time of declaration or in a constructor of the class.

Combining the static and final keywords creates a variable that is both constant and shared among all instances of the class. This is useful for defining global constants or variables that need to be accessed by multiple parts of the program without the risk of their values being changed unintentionally.

For example

consider a class that defines a constant for the value of pi:

```java

public class MathUtils {

public static final double PI = 3.14159;

}

```

In this example

the variable PI is declared as static final

which means it is a constant value that can be accessed by any part of the program without the risk of its value being changed. The value of PI will remain constant throughout the execution of the program

making it a reliable constant for calculations involving the value of pi.

In summary

the static final keyword in Java is used to define constant variables that are shared among all instances of the class and cannot be changed once assigned a value. This is useful for creating global constants or variables that need to be accessed by multiple parts of the program without the risk of their values being changed inadvertently.