java - 空指针异常，我不知道我做错了什么

Question

错误出现在第 26 行

import java.util.*;
import java.io.*;

public class PG1gbm {

public static void main(String[] args) {

    try {
        File input = new File("input.txt");
        Scanner infile = new Scanner(input);
        Scanner i1 = new Scanner(input);
        int count= 0;
        while(infile.hasNext()) {
            infile.nextLine();
            count++;
        }
        User[] userArray = new User[count];
        int loopCount = 0;
        while(infile.hasNext()) {
            //userArray[loopCount] = new User(i1.next(), Integer.parseInt(i1.next()), Integer.parseInt(i1.next()), Integer.parseInt(i1.next()),Integer.parseInt(i1.next()));
            userArray[loopCount] = new User(i1.next(), i1.nextInt(), i1.nextInt(), i1.nextInt(), i1.nextInt());
            //userArray[count] = user;
            loopCount++;
        }
        for(int i = 0; i < count; i++) {
            System.out.println(userArray[i].getid());
        }

    }
    catch(FileNotFoundException e) {
        System.out.println("There is no file present.");
    }
}

}

这是我要退出的类(class)

public class User
{
   private String userID;
   private int in_time;
   private int out_time;
   private int priority;
   private int plotter_sheets;


   public User (String id, int t1, int t2, int prio, int pc)
   {
      userID=id;
      in_time=t1;
      out_time=t2;
      priority=prio;
      plotter_sheets=pc;
   }

       return userID;
   }

   public int getintime(){
       return in_time;
   }

      public int getouttime(){
       return out_time;
   }

      public int getPriority(){
       return priority;
   }

      public int getSheets(){
       return plotter_sheets;
   }

   public String toString()
   {
      String description;

      description = userID + "\t" + in_time + "\t"+ out_time +
      "\t"+priority+"\t"+plotter_sheets;

      return description;
   }
}

Answer 1

我敢打赌这里的问题是你对文件的第二个循环永远不会真正执行，所以当你创建了一个userArray，一个User数组，数组元素已统一化。

仔细检查后，您的第二个循环可能应该使用 i1:

while(i1.hasNext())