Return array of integers except 0. How do I do?

Question

The method takes two numbers per parameter, and returns one array with the odd numbers between these two numbers.

public static int[] oddNumbers(int l, int r) {
    int odd[] = new int[r];
    for(int i=0; i<odd.length;i++){
        if(l<=r && l%2!=0){
            odd[i]=l;
        } l++; 
    }
        return odd;
}

However, it is returning the zeros in the array, and is to return only the odd.

At the moment, if put oddNumbers(2,5), the result will be: 0 3 0 5 0

How do I return only filled positions? 3 5

Answer 1

No need to create a array that fits all the generated elements, can make one with the amount of final elements. But you don’t need to filter anything, you can use math to know beforehand which are the odd ones. I haven’t made necessary validations. You can even simplify more, but not to complicate too much for beginners is this:

class HelloWord {
    public static void main (String[] args) {
        for (int i : oddNumbers(2, 5)) System.out.println(i);
    }

    public static int[] oddNumbers(int l, int r) {
        l += 1 - l % 2;
        r -= 1 - r % 2;
        int odd[] = new int[(r - l) / 2 + 1];
        for (int i = 0; i < odd.length; i++) odd[i] = l + (i * 2);
        return odd;
    }
}

Behold working in the ideone. And in the repl it.. Also put on the Github for future reference.