Question

I have an array of ints ie. [1,2,3,4,5] . Each row corresponds to decimal value, so 5 is 1’s, 4 is 10’s, 3 is 100’s which gives value of 12345 that I calculate and store as long.
This is the function :

public long valueOf(int[]x) {

    int multiplier = 1;
    value = 0;
    for (int i=x.length-1; i >=0; i--) {
        value += x[i]*multiplier;
        multiplier *= 10;
    }
    return value;
}

Now I would like to check if value of other int[] does not exceed long before I will calculate its value with valueOf(). How to check it ?
Should I use table.length or maybe convert it to String and send to

public Long(String s) ?

Or maybe just add exception to throw in the valueOf() function ?

Answer 1

I hope you know that this is a horrible way to store large integers: just use BigInteger.

But if you really want to check for exceeding some value, just make sure the length of the array is less than or equal to 19. Then you could compare each cell individually with the value in Long.MAX_VALUE. Or you could just use BigInteger.