Project Euler 24 using java Logical Error

I am trying to solve problem 24 https://projecteuler.net/problem=24 of the project euler and I have spent a lot of time on this problem but still no success.

But now it's not about the problem, I wanted to know what wrong with my method.

I am using simple permutation to get the leftmost digit and getting the remaining value from the term to be found (by subtracting i.e. using modulo operator).

Java Code:

import java.util.ArrayList;

public class LexOrder
{

public static int factorial(int num)
{
    int res=1;
    if(num <= 1)
        return 1;

    while(num > 1)  
    {
        res *= num--;   
    }
    return res;
}

public static ArrayList<Integer> addValue(int digit, ArrayList<Integer> al)
{
    int temp=0, count=0;    
    while( count <= digit )
    {
        if( al.contains(count) )
            temp++;
     count++;
    }

    int val = digit+temp;

    //checking weather the new number exists in the ArrayList or not.
    while(true)
    {
        if(! al.contains(val) )
        {
            al.add(val);
            break;
        }
        else
        {
            val++;
        }
    }
    return al;
}

public static void main(String args[])
{
    ArrayList<Integer> al = new ArrayList<Integer>();   
    int index = 999999; 
    int numOfDigit = 10;

    if( factorial( numOfDigit ) > index && index >= 0)
    {
            System.out.println("Index Validated");
    }
    else
    {
            System.out.println("Index out of bounds");
            System.exit(0);
    }

    int digit, count=1;
    while( index !=0  )
    {
        digit = ( index / factorial( numOfDigit - count ) );
        al = addValue(digit, al);

        index = ( index % factorial( numOfDigit - count ) );

        if(index == 0)
            break;
        count++;
    }

    // Adding value in ascending order.
    int temp =0;
    while( al.size() < numOfDigit )
    {

        if(!al.contains(temp))
            al.add(temp);

    temp++;
    }

    System.out.println(al);
}
}

Output: [2, 7, 8, 3, 9, 1, 4, 5, 6, 0]

Output should be: 2783915460