What is the best way to define constants in Java?

General Discussions
, ,
1

What is the recommended way to define constants in Java?

I’ve come across examples where constants are declared using public static final, like this:

public class MaxSeconds {
   public static final int MAX_SECONDS = 25;
}

Some suggest wrapping constants in a separate class, but as someone new to Java, I’m wondering if this is the best approach. How should I properly define a Java constant to ensure efficiency and good coding practices?

2

I’ve worked with Java for years, and the most common way to define a java constant is by using public static final inside a dedicated constants class. This keeps values immutable and globally accessible.

public class Constants {
    public static final int MAX_SECONDS = 25;
    public static final String APP_NAME = "MyApp";
}

Then, use it like this:

int timeout = Constants.MAX_SECONDS;

:white_check_mark: Why use this? :heavy_check_mark: Keeps constants organized

:heavy_check_mark: Prevents accidental modification

:heavy_check_mark: Improves code readability

:rotating_light: When to use?

:point_right: Best for shared constants used across multiple classes."

3

Great approach, @ishrth_fathima But if your java constant values are logically related, an enum is even better. Enums not only group constants but can also hold extra functionality.

public enum TimeConstants {
    MAX_SECONDS(25),
    MIN_SECONDS(5);

    private final int value;

    TimeConstants(int value) {
        this.value = value;
    }

    public int getValue() {
        return value;
    }
}

Then, use it like this:

java

CopyEdit

int timeout = TimeConstants.MAX_SECONDS.getValue();

:white_check_mark: Why use this?

:heavy_check_mark: Groups related constants

:heavy_check_mark: Ensures type safety

:heavy_check_mark: Allows additional behavior

:rotating_light: When to use?

:point_right: Best when constants belong to a category, like time limits or error codes."

4

Enums are great, But if you want a quick and direct way to access a java constant without using a class reference, an interface works too.

public interface TimeConfig {
    int MAX_SECONDS = 25;
    int MIN_SECONDS = 5;
}

Then, you can use:

int timeout = TimeConfig.MAX_SECONDS;

:white_check_mark: Why use this?

:heavy_check_mark: No need for Constants.MAX_SECONDS—just use it directly

:heavy_check_mark: Works well in small projects

:rotating_light: Downsides?

:x: Pollutes the namespace (everything is public)

:x: Not extendable like enums

:point_right: Use it when you need quick, direct access but avoid it for large-scale projects!"