לפניך שתי מחלקות: המחלקה MyArray והמחלקה Program.

import java.util.*;
public class MyArray
{
    private int[] arr;
    private Scanner in;

    public MyArray(int n)
    {
        in = new Scanner(System.in);
        arr = new int[n];
        for (int i = 0; i < n; i++)
            if (i % 2 == 0) arr[i] = 1;
            else arr[i] = -1;
    }

    public void one(int n)
    {
        for (int i = 0; i < n; i++)
            arr[i] = in.nextInt();
    }

    public void two()
    {
        for (int i = 0; i < arr.length; i++)
            System.out.println(i + " " + arr[i]);
    }

    public void three()
    {
        int lastPlace = arr.length - 1;
        int halfLen = lastPlace / 2;
        int temp;

        for (int i = 0; i <= halfLen; i++)
        {
            temp = arr[i];
            arr[i] = arr[lastPlace - i];
            arr[lastPlace - i] = temp;
        }
    }
}

class Program
{
    public static void main(String[] args)
    {
        MyArray star = new MyArray(8);
        System.out.println("------------------------------");
        star.two();
        star.one(6);
        System.out.println("------------------------------");
        star.two();
        System.out.println("------------------------------");
        star.three();
        star.two();
    }
}