Question

Here’s the relevant part of the Dice class:

import java.util.*;
class Dice 
{ 
    String name ; 
    int x ; 
    int[] sum ; 

…

public Dice (String name) 
    { 
        this.name = name ; 
        this.x = 0 ; 
        this.sum = new int[7] ; 
    }

…

public void roll () 
    {
        this.x = randNum(1, this.sum.length) ; 
        this.sum[x] ++ ;
    }

I am invoking this method in a separate class named Risk

class Risk 
{

Heres the first line of the method:

public static void IdiceRoll (Dice o)

So this method takes a dice that already exists as a paramater so theres no need to create a new dice inside it.

Finaly here is how i’m trying to invoke roll on o:

o.Dice.roll () ; 

Answer 1

In your other class, in some method, you need to get an instance of the class you’re trying to use. You need an import statement if you’re in another package.

Then it’s simple:

// Create an instance of class Dice named dice
Dice dice = new Dice();

// call the method on the instance you just created
dice.roll();

Also, refer to Sun’s documentation and try examples to get your feet under you.

Revision to match your changes:

public class Risk
{
   public static void IdiceRoll(Dice o)
   {
      o.roll();
   }
}