Throw defined messages for a Custom Exception in Java

I'm a newbie programming in Java (actually already learning) and I have some doubts about how to handle different messages.

My goal is to include in the same class (CustomException class) those different messages to avoid writing the same strings again and again on each method that throw new CustomExceptions from other classes.

Until now I coded:

1. A CustomException class that extends from Exception and has the different messages (only two in the example but there are many more) included as a Strings, and of course the constructors:

   public class CustomException class extends Exception {
   
       private static final String MSG_ERR_NUM1 = "Error number 1";
       private static final String MSG_ERR_NUM2 = "Error number 2";
   
       public CustomException() { super(); }
       public CustomException(String message) { super(message); }
       public CustomException(String message, Throwable cause) { super(message, cause); }
       public CustomException(Throwable cause) { super(cause); }
   }
   

2. Other different classes with some methods on them that throw new CustomException:

   public class Car {
   
     public void checkWheels() throws CustomException {
         if (comparison = true) {
              throw new CustomException(what to call??);
         }
     }
   }
   

3. A class with the main method where executes the try and catch:

    public class Driving {
   
        public static void main() {
             try {
                   //doSomething
             }
             catch (CustomException e) {
                e.printStackTrace();
             }
        }
    }
   

My questions are:

1. Would it be a good procedure to add code for different getter methods on CustomException class to get the text from each String?

     public String getErrorNum1() {
          return MSG_ERR_NUM1;
     }
   

2. How would I call these getters from the throws included in the methods of other classes?

         if (comparison = true) {
              throw new CustomException(what here to get MSG_ERR_NUM1 or MSG_ERR_NUM2 text instead writing a String every time??);
         }
   

Thanks in advance for your support.

You can add the desired string to the "message" in the exception's constructor like:

public class CustomException class extends Exception {

  private static final String MSG_ERR_NUM1 = "Error number 1";
  private static final String MSG_ERR_NUM2 = "Error number 2";

  public CustomException() { super(); }
  public CustomException(String message) { super(MSG_ERR_NUM1 + message); }
  public CustomException(String message, Throwable cause) { super(MSG_ERR_NUM1 + message, cause); }
  public CustomException(Throwable cause) { super(cause); }
}

If you want to throw different message for different situations, you use your public static final String fields:

and when you throw the Exception you give the enum cause throw new CustomException(CustomException.MSG_ERR_NUM2);

But I think it is better and cleaner to create different Exception class for different errors.