Question

I couldn’t find anything on that while googling
so
I want to create an array only if it doesn’t already exists.

EDIT: I mean not initialized

I know how to check for values in the array

Should be simple but I’m stuck

best regards

static long f(long n) {
    int m = (int)n;
    **if (serie == null) {

   long[] serie = new long[40];
    }**
    if (n == 0) {
        return 0;
    }
    else if (n==1) {
        return 1;
    }
    else {
        long asdf = f(n-1)- 2*(f(n-2)) + n;
        return asdf;
    }
}

something like that
a recursive function and I want to save the values in an array

Answer 1

Are you looking for:

if (values == null)
{
    values = new int[10];
}

or something like that? If not, please edit your question to provide more information.

EDIT: Okay, judging by the updated question, I suspect you ought to have two methods:

static long f(long n)
{
    return f(n, new long[40]);
}

static long f(long n, long[] serie)
{
    // Code as before, but when you recurse, pass in serie as well
}

(Note that your current code doesn’t use serie at all.)