java - 正在使用变量？

Question

我已经看到了关于同一问题的一些帖子，所以如果我错过了阅读某些内容，我深表歉意，但这个问题真的很烦我。所以我这里有这段代码:

int megaBytes = 0;
int megaByteSpeed = 0;
int totalSeconds = 0;
int secondsRemainder = 0;
int hours = 0;
int minutes = 0;
int seconds = 0;
Scanner sc = new Scanner(System.in);

和

if (megaBytes < 1000)
    {
        totalSeconds = megaBytes / megaByteSpeed;
        hours = totalSeconds / 3600;
        secondsRemainder = totalSeconds % 3600;
        minutes = secondsRemainder / seconds;
        seconds = minutes % 60;
    }

我知道我的编码可能有很大错误，但我是 Java 新手，我开始变得有点慌乱。 我收到的错误是变量； megaByteSpeed、totalSeconds 和 secondsRemainder 未使用。很明显，它们在数学部分是这样的。有谁知道为什么会发生这种情况？这导致我的项目在运行中停止。

感谢您提供任何信息， 斯奎尔.

整个代码:

public class Ch03_ex3_DownloadTime {
  /**
   * @param args the command line arguments
   */
  public static void main(String[] args) 
  {
    System.out.println("Welcome to the Download Time Estimator!");
    System.out.println();

    int megaBytes = 0;
    int megaByteSpeed = 0;
    int totalSeconds = 0;
    int secondsRemainder = 0;
    int hours = 0;
    int minutes = 0;
    int seconds = 0;
    Scanner sc = new Scanner(System.in);

    while (megaBytes != 1000)
    {
      System.out.print("Enter download size: ");
      megaBytes = sc.nextInt();

      System.out.print("Enter download speed: ");
      megaByteSpeed = sc.nextInt();

      if (megaBytes < 1000)
      {
        totalSeconds = megaBytes / megaByteSpeed;
        hours = totalSeconds / 3600;
        secondsRemainder = totalSeconds % 3600;
        minutes = secondsRemainder / seconds;
        seconds = minutes % 60;
      }
      String message = "\n" 
                   +  "This download will take approximately " + hours + "hours" + minutes + "minutes and " + seconds + "seconds";
      System.out.println(message);
    }
  }
}

Answer 1

首先让我给您一个提示:按照网站上有关如何发布代码的说明进行操作。

现在，从你的代码中我可以看出你正在除以 0 这里:

    minutes = secondsRemainder / seconds; 

这是您需要更改以停止循环的部分

    boolean quit = false;
    while (!quit)
    {
        System.out.print("Enter download size: ");
        megaBytes = sc.nextInt();

        System.out.print("Enter download speed: ");
        megaByteSpeed = sc.nextInt();

    if (megaBytes < 1000)
        {
            totalSeconds = megaBytes / megaByteSpeed;
            hours = totalSeconds / 3600;
            secondsRemainder = totalSeconds % 3600;
            minutes = secondsRemainder / seconds;
            seconds = minutes % 60;

        }
        String message = "\n" 
                       +  "This download will take approximately " + hours + "hours" + minutes + "minutes and " + seconds + "seconds";
        System.out.println(message);

        System.out.println("Do you want to continue 1= yes 0 = no");
        int ans  = 0;
        ans = sc.nextInt();
        if(ans ==0){
            quit = true;
        }
    }