Java Exception in thread "main" java.util.NoSuchElementException 运行时错误

Question

我一直在制作一个简单的java程序作为学校的家庭作业。当我添加了一个从.txt文件中检索2D数组的方法时，出现了这个错误。程序在编译时不会显示任何错误。我是一个新程序员，所以请仔细检查任何添加或更改的内容。除了手头的问题，请随时给我更多的提示和建议。

提前感谢

这是代码：

import java.util.*;
import java.io.*;
public class simpleAI2
{
   public static void main (String [] args)
   {
      int count = 0;
      String[][] array = new String [20][4];
      simpleAI2.getArrayData(array);
      String leaveQ;
      int rep = 1;
      do
      {
         int countTwo = 0;
         boolean flag = false;
         Scanner scanName = new Scanner (System.in);
         Scanner scanSport = new Scanner (System.in);
         Scanner leave = new Scanner (System.in);

         System.out.println("My name is A.I.S.C.M.B.T. What is your name?");
         array[count][1] = scanName.nextLine ();
         System.out.println("Hi "+array[count][1]+"! What's your favourite sport?");
         array[count][2] = scanSport.nextLine ();
         String sport = array[count][2];
         for(int x = 1;x<rep;x++)
         {
            if(!array[countTwo][2].equals(null) && array[countTwo][2].equals(array[count][2]))
               {
               flag = true;
               x = 28;
               }
            else
               {
               flag = false;
               }
            countTwo ++;
         }

         countTwo --;
         if(flag == true)
            {
            System.out.println("I know "+array[countTwo][2]+". It is "+array[countTwo][3]+". My friend "+array[countTwo][1]+" knows it");
            }
         if(flag == false)
            {
            System.out.println("I don't know "+array[count][2]+". I only know robot boxing. Robots hit each other until one malfunctions. What is this alien sport you speak of?");
            array[count][3] = scanSport.nextLine ();
            }
         System.out.println("Go again? Type no to leave me :(");
         leaveQ = leave.nextLine ();
         rep ++;
         count ++;
         if(leaveQ.equals("no"));
            {
            simpleAI2.Save(array);
            }
      }while (!leaveQ.equals("no"));
   }

   public static void Save(String [][] array){
      try {
         PrintWriter writer = new PrintWriter(new File("arrayData.txt"));
         for(int x=0; x<array.length; x++){
            for(int y=0; y<array[x].length; y++){
               writer.write(String.valueOf(array[x][y]));
            }
            writer.println(); 
         }
         writer.flush();  
         writer.close();        

      } 
      catch (FileNotFoundException e) 
         {      
         e.printStackTrace();
         }

   }
   public static void getArrayData(String [][] array){
      try {
         Scanner scan2 = new Scanner(new File("arrayData.txt"));
         for(int i=0; i<array.length;  i++){
            for(int j=0; j<array[i].length; j++)
            {
               array[i][j]=scan2.next(); 

            }
         }

      } 
      catch (FileNotFoundException e)
         { 
         e.printStackTrace(); 
         }    
   }
}

Answer 1

如果在没有剩余内容可读取时调用Scanner函数next（），它将抛出一个NoSuchElementException
将您的代码更改为以下内容：

public static void getArrayData(String [][] array)
{
    try 
    {
        Scanner scan2 = new Scanner(new File("arrayData.txt"));
        for(int i=0; i<array.length;  i++)
        {
            for(int j=0; j<array[i].length; j++)
            {
                if ( ! scan2.hasNext() )  //if there's nothing left to read
                    return;               //exit the function
                array[i][j]=scan2.next(); 
            }
        }
    } 
    catch (FileNotFoundException e)
    { 
        e.printStackTrace(); 
    }    
}