java - 无法弄清楚为什么程序无法正常运行

Question

我一直在尝试让这个程序正常工作，它应该继续接受用户的输入，直到输入 -1 并计算总和。问题如下: 设计并实现一个 Java 程序(将其命名为输入和)，提示用户输入一个正整数。该程序应接受整数，直到用户输入值 -1(负数)。用户输入-1后，程序应显示输入的数字及其总和如下所示。请注意，-1 不是输出的一部分。确保程序在 proc 之前验证每个输入的数字当用户可能输入否定时进行处理句子值-1以外的数字.
设计你的程序，使其 允许用户重新运行如上所示，在同一运行中具有不同输入集的程序。 记录您的代码，并组织和如上所示间隔输出。

这是我的代码:

/* Class:        CS1301
* Section:       9:30
* Term:          Fall 2015
* Name:          Matthew Woolridge
* Instructor:    Mr. Robert Thorsen
* Assignment:    Assignment 6
* Program:       1
* ProgramName:   InputSum
* Purpose:       The program prompts the user to input numbers until -1 is entered and calculates the sum
* Operation:     The information is statically instantiated in the code and
*                the data is output to the screen.
* Input(s):      The input is the numbers
* Output(s):     The output will be the sum of the numbers
* Methodology:   The program will use loops to determine if numbers or still to be entered or if -1 was entered
*
*/

import java.util.*;
import java.io.*;
public class InputSum
{

   public static void main (String[] args)
   {

      /******************************************************************************
      *                          Declarations Section                               *
      ******************************************************************************/
      /****************************CONSTANTS********************************/
      Scanner scan = new Scanner(System.in); //Initializes scanner

      int n = 1;
      int [] num = new int[n]; //Creates array for input numbers
      int i;
      int sum=0;

      /******************************************************************************
      *                             Inputs Section                                  *
      ******************************************************************************/

      System.out.print("Please input integers, note that -1 ends the submissions: "); //Prompts the user for input

     /****************************variables********************************/
     //***************************Calculations in processing************************//
     /******************************************************************************
      *                             Processing Section                            *
      ******************************************************************************/
      for(i=0; i<num.length; i++)
      {
         num[i] = scan.nextInt(); //Continues to read numbers and add them to the sum
         n = n + 1; //Adds to the array maximum
         sum = sum + num[i]; //Calculates the sum
         if (num[i] == -1){
            break;
         }
      }
      System.out.print("The numbers entered are: " + num[i]);
      System.out.print("\nThe sum of the numbers is: " + sum);

      /******************************************************************************
       *                              Outputs Section                                *
       ******************************************************************************/
       //***************Output is in the processing**************************//
   }
}

问题是，程序总是卡在应该打印总和的行上。感谢任何和所有的帮助!

Answer 1

您可以使用列表来存储数字，并使用无限循环来不断接收用户的输入。此外，您应该在开始处理数字之前检查停止条件(因为您的问题提到 -1 不是输出的一部分)。这是一个说明

import java.util.*;
import java.io.*;
public class InputSum
{

   public static void main (String[] args)
   {

      /******************************************************************************
      *                          Declarations Section                               *
      ******************************************************************************/
      /****************************CONSTANTS********************************/
      Scanner scan = new Scanner(System.in); //Initializes scanner
      int number; //Declare a variable that will hold the temporal value that is read on the input stream      
      int sum=0;

      // Use a List 
      List<Integer> numbers = new ArrayList<Integer>();

      /******************************************************************************
      *                             Inputs Section                                  *
      ******************************************************************************/

      System.out.print("Please input integers, note that -1 ends the submissions: "); //Prompts the user for input

     /****************************variables********************************/
     //***************************Calculations in processing************************//
     /******************************************************************************
      *                             Processing Section                            *
      ******************************************************************************/
      // use an infinite loop
      for(; ; )
      {


         // You should normally do this check when you enter the loop
         // so that -1 which is a stop token should not be added to the list
         // and not taken into account in the sum


         number = scan.nextInt(); //Continues to read numbers and add them to the sum
         if (number == -1){
              break;
         }

         // You could write numbers.add(number) which would be
         // Java's autoboxing feature, but this is what would really take place
         numbers.add(Integer.valueOf(number));
         sum += number; //Calculates the sum


      }
      System.out.print("The numbers entered are: " + numbers);
      System.out.print("\nThe sum of the numbers is: " + sum);

      /******************************************************************************
       *                              Outputs Section                                *
       ******************************************************************************/
       //***************Output is in the processing**************************//
   }
}