java - 未使用的声明使我的程序正常工作吗？

Question

所以我编写了这段代码，并在其中编写了“int number = input.nextInt();”作为实验。该程序完全按照我的要求执行，但我不明白为什么会这样。该变量稍后在程序中根本不会使用，但如果我删除它，程序将停止工作。有任何想法吗？我的代码如下:

import java.util.Scanner;
/*
 * Name: Ki
 */
public class Countdown {
    public static void main(String[] args) {
        //Create a Scanner object to accept the input from user
        Scanner input = new Scanner(System.in);

        // Prompt the user to enter starting number, I just set it to 5 because 
        // that's what the program had as standard input.
        System.out.println("Enter the beginning number: ");

        // I don't know how this works. I had this here as an experiment, but
        // the program now doesn't work without it so I guess I'll leave it here.
        int number = input.nextInt();

        // sets max countdown value
        int i=5;

        // Make a loop that makes the program countdown until it reaches 2
        while(i>1) 
        {
            System.out.print(i + " ... \n");
            i--;
        }
        // Makes the program print 1 without dots and print stopped at the end 
        if (i==1) System.out.println(i);
        System.out.print("Stopped");
    }
}

Answer 1

 int number = input.nextInt();

    // sets max countdown value


    // Make a loop that makes the program countdown until it reaches 2
    while(number>1) 
    {
        System.out.print(number + " ... \n");
        number--;
    }
    // Makes the program print 1 without dots and print stopped at the end 
    if (number==1) System.out.println(number);
    System.out.print("Stopped");