public class BinarySearch {
    public static void main(String[] args) {
        int[] arr = { 3, 6, 9, 12, 15 };
        int key = 15;
        int arrlength = arr.length;
        binarySearch(arr, 0, key, arrlength);
    }

    public static void binarySearch(int[] arr, int start, int key, int length) {
        int midValue = (start + length) / 2;
        while (start <= length) {
            if (arr[midValue] < key) {
                start = midValue + 1;
            } else if (arr[midValue] == key) {
                System.out.println("Element is found at index: " + midValue);
                break;
            } else {
                length = midValue - 1;
            }
            midValue = (start + length) / 2;
        }
        if (start > length) {
            System.out.println("Element is not found");
        }
    }
}