How do I find the largest negative value in an array with both positive and negative values?

Question

I need to return the greatest negative value, and if there are no negative values, I need to return zero. Here is what I have:

public int greatestNegative(int[]          


        

Answer 1

Start by setting your "maxNegative" value to 0. Then assign the first negative number you come across. After that, only assign negative numbers that are higher. If there are no negative numbers, then your "maxNegative" will still be zero.

public static void main(String[] args) {
    int arr[] = {2, -1, 4, 1, 0, 7, 2, -3, 5, 9, -4, 5, -9};
    int maxNegative = 0;
    for (int i = 0; i < arr.length; i++) {
        if (maxNegative == 0 && arr[i] < maxNegative) {
            // Set the first negative number you come across
            maxNegative = arr[i];
        } else if (maxNegative < arr[i] && arr[i] < 0) {
            // Set greater negative numbers
            maxNegative = arr[i];
        }
    }
    System.out.println(maxNegative);
}

Results:

-1

Java 8

Then there are streams, that allow you to do this with one line of code.

public static void main(String[] args) {
    int arr[] = {2, 4, 1, 0, 7, 2, -3, 5, 9, -4, 5, -9};
    int maxNegative = Arrays.stream(arr).filter(a -> a < 0).max().orElse(0);
    System.out.println(maxNegative);
}

Results:

-3