importance of constants
Constants in Java are variables whose values do not change throughout the execution of a program. They are used to represent fixed values that remain constant and immutable during the runtime of the program. Constants are typically declared with the final keyword to indicate that their values cannot be modified once initialized.

Table of Contents
Here’s how to create constants in Java:
1. Using the ‘final’ Keyword:
- The ‘final’ keyword is used to declare constants in Java.
- Constants declared with ‘final’ keyword must be initialized at the time of declaration or in a constructor.
- Once initialized, the value of a ‘final’ variable cannot be changed throughout the program execution.
Example
public class ConstantsExample {
// Declaring constant variables
public static final int MAX_VALUE = 100;
public static final double PI = 3.14159;
public static final String MESSAGE = "Hello, world!";
public static void main(String[] args) {
// Accessing constant variables
System.out.println("Max value: " + MAX_VALUE);
System.out.println("PI: " + PI);
System.out.println("Message: " + MESSAGE);
}
}
2. Using ‘static’ and ‘final’ Together:
- Constants can also be declared as static final within a class to make them class-level constants accessible without creating an instance of the class.
- ‘static final’ constants are shared across all instances of the class.
Example
public class ConstantsExample {
// Declaring static final constant variables
public static final int MAX_VALUE = 100;
public static final double PI = 3.14159;
public static final String MESSAGE = "Hello, world!";
public static void main(String[] args) {
// Accessing static final constant variables
System.out.println("Max value: " + ConstantsExample.MAX_VALUE);
System.out.println("PI: " + ConstantsExample.PI);
System.out.println("Message: " + ConstantsExample.MESSAGE);
}
}
By declaring constants in Java, you ensure that their values remain consistent and immutable throughout the program, making the code more readable, maintainable, and error-resistant.