I want to reverse the order of the int-type array, how can I do that?

When you flip the arrangement, hold the middle point and swap the ends.

for(int i = 0; i < validData.length / 2; i++)
{
    int temp = validData[i];
    validData[i] = validData[validData.length - i - 1];
    validData[validData.length - i - 1] = temp;
}

You can do it like this. What's wrong with the above is that when you swap elements at both ends, you change the changed part again after the middle It's because it swaps twice and eventually returns to its original state.