SumsArray

package com.company;
import java.util.Scanner;

public class Main {

    public static int inputLength() {
        Scanner scan = new Scanner(System.in);
        int length = 0;
        boolean isIncorrect;
        System.out.println("Enter the length of the array (from 1 to 20)");
        do {
            isIncorrect = false;
            try {
                length = Integer.parseInt(scan.nextLine());
            } catch (Exception e) {
                System.out.println("Incorrect input!\nEnter the integer");
                isIncorrect = true;
            }
            if (!isIncorrect && (length < 1 || length > 20)) {
                System.out.println("Incorrect input!\nEnter the length of the range from 1 to 20");
                isIncorrect = true;
            }
        } while (isIncorrect);
        return length;
    }

    public static void inputArray(double[] array) {
        Scanner scan = new Scanner(System.in);
        boolean isIncorrect;

        for (int i = 0; i < array.length; i++) {
            do {
                isIncorrect = false;
                System.out.println("Enter the array element at number " + (i + 1));
                try {
                    array[i] = Double.parseDouble(scan.nextLine());
                } catch (Exception e) {
                    System.out.println("Incorrect input!\nEnter the number");
                    isIncorrect = true;
                }
            } while (isIncorrect);
        }
    }

    public static void printArray(double[] array) {
        System.out.println("Array: ");
        for (double element : array) {
            System.out.print(element + "; ");
        }
        System.out.println("\n");
    }

    public static double findSumOfOddElements(double[] array) {
        double sum = 0;
        for (int i = 0; i < array.length; i++) {
            if (i % 2 == 0) {
                sum += array[i];
            }
        }
        return sum;
    }

    public static int findIndexOfFirstNegative(double[] array) {
        int i = 0;
        int firstNegative = -1;
        boolean isNotFound = true;
        while (i < array.length && isNotFound) {
            if (array[i] < 0) {
                isNotFound = false;
                firstNegative = i;
            }
            i++;
        }
        return firstNegative;
    }

    public static int findIndexOfLastNegative(double[] array) {
        int i = array.length - 1;
        int lastNegative = -1;
        boolean isNotFound = true;
        while (i > 0 && isNotFound) {
            if (array[i] < 0) {
                isNotFound = false;
                lastNegative = i;
            }
            i--;
        }
        return lastNegative;
    }

    public static double findSumBetweenNegatives(double[] array, int firstNegative, int lastNegative) {
        int sum = 0;
        for (int i = firstNegative + 1; i < lastNegative; i++) {
            sum += array[i];
        }
        return sum;
    }

    public static void outputResult (double sumOfOddElements,  double sumBetweenNegatives, int firstNegative, int lastNegative) {
        if (firstNegative != -1 || lastNegative != -1) {
            System.out.println("The sum of odd elements of the array is " + sumOfOddElements);
            System.out.println("The sum between the first and last negative array element is " + sumBetweenNegatives);
        } else {
            System.out.println("The sum of even elements of the array is " + sumOfOddElements);
            System.out.println("The array does not contain at least two negative elements");
        }
    }

    public static void main(String[] args) {
        int length = inputLength();
        double[] array = new double[length];
        inputArray(array);
        printArray(array);
        double sumOfOddElements = findSumOfOddElements(array);
        int firstNegative = findIndexOfFirstNegative(array);
        int lastNegative = findIndexOfLastNegative(array);
        double sumBetweenNegatives = findSumBetweenNegatives(array, firstNegative, lastNegative);
        outputResult(sumOfOddElements, sumBetweenNegatives, firstNegative, lastNegative);
    }
}