Arrays.sort(arr);

int minimumDifference = Integer.MAX_VALUE;

for (int i = 0; i < arr.length - 1; i++) {
    int difference = arr[i + 1] - arr[i];
    
    if (difference < minimumDifference) {
        minimumDifference = difference;
        
        if (minimumDifference == 0) {
            return 0;
        }
    }
}

return minimumDifference;