Question

I am creating instances of a class with extends Button and accessing an integer variable directly for better performance. I’m using constants to easily identify the variable’s current setting.

I have the constants declared both the Button class and in the Activity class which is instantiating them. I have found similar questions and read it’s not good practice to create a class just to hold constants.

What is the best way to use the same constant declaration in both classes?

I am a beginner programmer so it’s quite possible I am overlooking a simple solution.

Button class:

public class GridButton extends Button {
  public int displayStatus;

  // constants for mine display status
  private static final int UNTOUCHED = 1;
  private static final int UNCOVERED = 2;
  private static final int FLAGGED = 3;
  private static final int HIT = 4;
  ...
}

Activity class:

public class PlayGameActivity extends Activity {      
  private GridButton[][] gridButtons;      

  // constants for mine display status
  private static final int UNTOUCHED = 1;
  private static final int UNCOVERED = 2;
  private static final int FLAGGED = 3;
  private static final int HIT = 4;
  ...

  // e.g. accessing displayStatus value
  if (gridButtons[currentRow][currentColumn].displayStatus == FLAGGED)
  {
  }
}

Answer 1

To share things, you could make the constants in a separate class and access it statically

class Constants {
  public static final int UNTOUCHED = 1;
}

And then in both classes you could go Constants.UNTOUCHED.

In this case, I’d avoid using magic numbers and replace them with an Enum.

enum DisplayStatus {
  Untouched, Uncovered, Flagged, Hit
}

And replace all of your int displayStatus with DisplayStatus displayStatus. Now it’s clearly to you and other readers of the code what that int represents.

Ideally you always want to use a specific type to restrict the range of possible values. In your example, only the numbers 1-4 are valid, but your type is as wide as an int so could be any value (e.g. -1 or 23543).

Good luck!