Java – How to define a class of constants in Java

class-constantsjava

Suppose you need to define a class which all it does is hold constants.

public static final String SOME_CONST = "SOME_VALUE";

What is the preferred way of doing this?

  1. Interface
  2. Abstract Class
  3. Final Class

Which one should I use and why?


Clarifications to some answers:

Enums – I'm not going to use enums, I am not enumerating anything, just collecting some constants which are not related to each other in any way.

Interface – I'm not going to set any class as one that implements the interface. Just want to use the interface to call constants like so: ISomeInterface.SOME_CONST.

Best Solution

Use a final class. for simplicity you may then use a static import to reuse your values in another class

public final class MyValues {
  public static final String VALUE1 = "foo";
  public static final String VALUE2 = "bar";
}

in another class :

import static MyValues.*
//...

if(variable.equals(VALUE1)){
//...
}