public class MainClass {

    public static void main(String[] args) {
        int[] array = {12, 14, 14, 89, 11, 10};
        int[] resultArray = changeByDomainLogic(array);
        for(int i = 0; i < resultArray.length; i++) {
            System.out.print(array[i] + " ");
        }
    }

    private static int[] changeByDomainLogic(int[] array) {
        if(checkIfArrayEven(array)) {
            array[0] = sumOfSecondPart(array);
        }
        return array;
    }

    private static int sumOfSecondPart(int[] array) {
        int sum  = 0;
        int mediumIndex = array.length / 2 ;
        for(int i = mediumIndex; i < array.length; i++) {
            sum += array[i];
        }
        return sum;
    }

    private static boolean checkIfArrayEven(int[] array) {
        if(array.length == 0) return false;
        return array.length % 2 == 0;
    }
}