数组无法识别

Question

我的程序是输入 10 个数字并将它们相加，然后显示结果。然后我将较小的数字除以较大的数字并显示结果。用户不能输入字符或零。

我是新手，已经为此工作了 DAYS。我没有看到我的错误。

现在我的问题是变量 i 未被识别。

我引入了一个异常 (try..catch)，但它无法读取。我试着把东西搬过来（我是新来的，我在猜测，看看有什么作用..）我做错了什么，可能是一些愚蠢的小事。我需要一些帮助和新鲜的眼睛。

当用户输入 9999 时，我还需要结束程序。知道那会去哪里吗？因为我快要泪流满面了。

public static void main(String[] args) throws NumberFormatException {
    Scanner in = new Scanner(System.in);
    Scanner input = new Scanner(System.in);

    double[ ] digit = new double[11];
    int sum = 0;
    //Declare an array


    System.out.print("Please Enter Ten Numbers:");
    System.out.println();

    try{
    for (int i = 1; i < digit.length; i++) 
        System.out.print("Numbers " + i + ": ");
        digit[i] = (double)in.nextInt(); //Array Not recognized here
        sum += (int)digit[i];//Or recognized here
// Input the data into array from the user.

     if(digit[i]==0.0)//None of these are recognized either, what did I do? 
        {
            System.out.println("You can't enter zero. Try again");
            --i; //nope
            in.nextLine();//dispose of wrong number
        }
        }catch (NumberFormatException e){

        System.out.println("You Can Only Enter Numbers!");
            --i; //nope, not recognizing here either
            in.nextLine();//dispose of wrong input
        }

    System.out.println("Total Values in Array:"+ sum);
     // Calculate the sum and print the total


    System.out.println();
    System.out.println("Would you like to divide the values?");
    System.out.println("Yes or No to Exit the Program");
    String a = input.next();

     if(a.equalsIgnoreCase("yes")){   
            double [] divisionResult = new double[digit.length / 2];
//Division array declared

            for (int i = 1; i < digit.length; i += 2)
 //These are all good and recognized. No problem with the division part
            {
            double result = digit[i];
            if (result > digit[i + 1]) 
            result = result / digit[i + 1]; 
    else {
            result = digit[i + 1] / result;
        }
            divisionResult [i / 2] = result;
                System.out.println(result);
            }
        }
    else if(a.equalsIgnoreCase("no")){
       System.exit(0);
    }
    }
 }

}

Answer 1

你的 for 循环没有大括号。只有它下面的第一行是循环的一部分。

Answer 2

for 循环的内容需要用大括号括起来。

Answer 3

我已尝试修改附加代码sn-p。希望这对您有所帮助。

package com.so.general;

import java.util.Scanner;

public class AddNumbers
{
  private static final int SIZE_OF_ARRAY = 10;
  public static void main(String[] args)
  {
    int counter = 0;
    double sumOfTenDigits = 0.0;
    double[] digit = new double[SIZE_OF_ARRAY];
    int listOfElements = digit.length;
    System.out.print("Please Enter Ten Numbers:"+"\n");
    Scanner readInputFromUser = new Scanner(System.in);

    try
    {
        for (counter=0; counter<listOfElements; counter++)
        {
            System.out.print("Numbers " + (counter+1) + ": ");
            digit[counter] = Double.parseDouble(readInputFromUser.next());
            if(digit[counter] == 0.0)
            {
                System.out.println("Zero is not allowed. Please try again.");
                System.out.print("Numbers " + (counter+1) + ": ");
                digit[counter] = Double.parseDouble(readInputFromUser.next());
            }
            sumOfTenDigits += digit[counter];
        }
    }
    catch(NumberFormatException numberFormatExcep)
    {
        System.err.println(" You have entered other than numbers. Only numbers are allowed. Terminating the program.");
        numberFormatExcep.printStackTrace();
        System.exit(0);
    }

    System.out.println("Addition is: "+ sumOfTenDigits);
    System.out.println("Would you like to divide the values? Press Y to continue, any other character to terminate the program.");

    Scanner continueWithDivide = new Scanner(System.in);
    String userInput = continueWithDivide.nextLine();

    closeScanner(readInputFromUser);
    closeScanner(continueWithDivide);

    if(readInputFromUser != null)
    {
        readInputFromUser.close();
    }

    // Always use static string literals on the left hand side. 
    // This prevents Null pointer exception.
    if("Y".equalsIgnoreCase(userInput))
    {   
        double[] divisionResult = new double[listOfElements/2];
        for(int i=0; i<listOfElements; i+=2)
        {
           double result = digit[i];
           if (result > digit[i+1])
           {
               result = result/digit[i+1];
           }
           else 
           {
               result = digit[i+1]/result;
           }
           divisionResult[i/2] = result;
           System.out.println(result);
        }
    }
    else
    {
       System.out.println("You have entered "+userInput+". Terminating the program.");
       System.exit(0);
    }
}

/**
 * Closed the scanner
 * @param scanner
 */
public static void closeScanner(Scanner scanner)
{
    if(scanner != null)
    {   try
        {
            scanner.close();
        }
        catch(IllegalStateException illegatStateExcep)
        {
            System.err.println("Scanner is already closed.");
            illegatStateExcep.printStackTrace();
        }
    }
}

请注意以下几点：

• 始终使用正确的缩进。
• 始终匹配 { }

• 即使您的if 或for 只有一个语句，也请使用{ }。

  For example: 
  
  for (int counter=1; i<digit.length; i++) 
  {
     System.out.print("Numbers " + i + ": ");
  }
  

  如果您的程序出现问题，上述三点将为您节省大量时间。

• 为变量和方法使用正确的名称。

• 在使用完之后总是关闭 IO 资源。

  For example:
  
  if(scanner != null)
  {
     scanner.close();
  }