Java, non-static cannot be reference to static context

问题

Doing Java course, at UNI atm, and I'm having a bit of trouble with a dice-problem.

I have the following:

 public class Die {
   public int eyes;
   private java.util.Random r;
   private int n;

   public Die (int n) {
     r = new Random();
     this.n = n;
   }

   public void roll() {
     eyes = r.nextInt(Die.n);
   }

When compiling I get: non-static variable n cannot be referenced from a static context. How would I go about fixing this, whilst having it randomize from a user given value?

回答1:

n is not a static variable, so you cannot refer to it in a static manner (Die.n).

Since it is an instance variable in the Die class, and you are referring to it in the Die class, you can just use n instead of Die.n.

回答2:

Remove

Die.n

and change it to simply

n

If n were declared static, you could use the both notations, even though the first one would be redundant (because you're from the inside of containing class)

来源：https://stackoverflow.com/questions/32595371/java-non-static-cannot-be-reference-to-static-context