List of Non-Repeating Ints in Java? Assignment

I'm trying to create a list of 20 integers between 0 and 26 (so in the 1-25 range) that does not repeat as a part of an assignment. I thought I had it figured out, but the program keeps looping over and over without ever ending. Can anyone help me out?

import java.util.Random;

public class prog433a
{
    public static void main(String args[])
    {
            Random r = new Random();

            int[] list = new int[20];

            for (int k = 0; k < list.length; k++)
            {
                boolean notADupe = false;

                while (notADupe == false)
                {
                    list[k] = r.nextInt(25) + 1;
                    for (int j = 0; j < list.length; j++)
                    {
                        if (list[j] == list [k] && j != k)
                        {
                            notADupe = true;
                        }
                        else
                        {
                            notADupe = false;
                            break;
                        }

                    }

                System.out.println(list[k]);
            }
        }
    }
}

EDIT: This is different from the other question because I am trying to figure out how to check for uniqueness using the methods that I am allowed to use in my assignment (essentially, the ones I'm already using in the code).