import java.util.*;

class Fasc {
    long num;

    void input() {
        Scanner sc = new Scanner(System.in);
        System.out.print("Enter a number: ");
        num = sc.nextLong();
        sc.close();
    }

    boolean is_fasc() {
        if (num < 100)
            return false;
        long n2 = num * 2, n3 = num * 3;
        int[] cnt = new int[10];
        String join = "" + num + n2 + n3;
        num = Long.parseLong(join);
        while (num != 0) {
            int dig = (int) (num % 10);
            cnt[dig]++;
            num /= 10;
        }
        for (int x = 1; x < 10; x++) // we have to ignore 0s
            if (cnt[x] != 1)
                return false;
        return true;
    }

    public static void main(String[] args) {
        Fasc a = new Fasc();
        a.input();
        System.out.println("Is " + (a.is_fasc() ? "" : "not ") + "a Fascinating number");
    }
}

Algorithm

void main()

1. Initialize a object of class Fasc named as 'a', to call the methods.
2. invoke the input method using the 'a' object.
3. Use the 'is_fasc' method to check it is a fascinating number and accordingly display the appropriate messages.

boolean is_fasc()

1. The number has to be atleast of 3 digits, so if the number is smaller than 100 return false.
2. Initialize variables n2, n3 storing double and triple of the entered number 'num'.
3. Initialize a integer array 'cnt' of size of 10 in order to store the count of each digit.
4. Concat num, n2 and n3 as string and parser it back to a integer and store it in 'num'.
5. Start a while loop with condition num!=0.
6. Extract the last digit of 'num' and store it in an integer 'dig'.
7. increment value of cnt[dig] by 1 as this stores the count of digit.
8. Divide num by 10 and store it in num.
9. End While Loop
10. Start a for loop with value of x as 1, condition as x < 10 and x=x+1 (Starting x from as we don't want to check freequency of zero).
11. if cnt[x] is not 1 then return false, as this means that the digit is not unique and thus violates condition to be fascinating.
12. End for loop
13. Return true as it is a fascinating number.

void input()

1. Initialize the Scanner object with argument System.in to take input.
2. Enter the number into global variables 'num'.