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Android

Timothy Boland
Timothy Boland
18,237 Points
Posted by Timothy Boland
Timothy Boland
18,237 Points

Android Activity Lifecycle | Creating the Adapter | Just curious why not start with int i = 1 instead of i = 0

I noticed you prefer to increment the for loop with:

    for (int i = 0; i < mHoles.length; i++) {
        mHoles[i] = new Hole("Hole" + (i + 1) + " :" +, strokes);
    }

I prefer to start with 1 like this, so I wont have to do the +1 later...and so its clear from the beginning whether , I truly am starting count by 0 or 1 with the data Im using

    for (int i = 1; i <= mHoles.length; i++) {
        mHoles[i] = new Hole("Hole" + (i) + " :" +, strokes);
    }

Is your way better? Is there a performance-gain im not aware of? Or a reason for this as a best practice?

1 Answer

J.D. Sandifer
J.D. Sandifer
18,813 Points
J.D. Sandifer
J.D. Sandifer
18,813 Points

Arrays are generally indexed starting with 0. I.e. array[0] is the first item and array[1] is the second.

Both styles you show would loop the same number of times, but the second hits an "array out of bounds" exception if you just do mHoles[i]. The line needs to be like this:

mHoles[i-1] = new Hole("Hole" + (i) + " :" +, strokes);

Since mHoles[length-1] is the last slot in the array.

As you can see, in an example where the array slots need to hold numbers starting with 1, you end up either adding 1 to the index to get the number or subtracting 1 from the index to get the slot since array[0] holds 1, array[1] holds 2, etc. Either way can make sense in that case.

However, there are a lot of times where you just want to loop through an array and then it makes less sense to keep writing array[index-1] when you aren't also trying to count up from 1.

Thus, for consistency it can make sense to always start with index = 0.

(That being said, I believe there is at least one language that accesses arrays starting at index 1 which solves that problem. Unless you want to count up from 0...)