Question

我正在尝试（只是为了使分级电影更加容易；将您要添加的电影与列表中的其他电影进行比较，以了解适合的电影很难并且效率不高）该程序的工作方式类似于binary insertion sort，用于以正确的顺序将电影添加到其他电影的列表中。在确定电影应该播放的列表中的位置的部分中，我遇到了错误

Exception in thread "main" java.util.NoSuchElementException: No line found
    at java.util.Scanner.nextLine(Unknown Source)
    at Rater.binarySearch(Rater.java:32)
    at Rater.main(Rater.java:24)

我不确定是什么原因造成的。代码如下：

import java.awt.List;
import java.io.*;
import java.util.ArrayList;
import java.util.Scanner; 
public class Rater 
{ 
  public static void main(String[] args)throws Exception 
  { 
      File file = new File("E:\\topmovies.txt"); 

      BufferedReader br = new BufferedReader(new FileReader(file)); 

      String st; 
      ArrayList<String> movList = new ArrayList<String>();
      while ((st = br.readLine()) != null) {
        movList.add(st);
      } 
      br.close();
      while(true) {
          System.out.println("Enter a movie to add.");
          Scanner myObj = new Scanner(System.in);
          String userName = myObj.nextLine(); 
          myObj.close();
          int index = binarySearch(movList, userName, 0, movList.size()-1);
          movList.add(index, userName);
      }
  }

  static int binarySearch(ArrayList<String> a, String item, int low, int high) 
  { 
      Scanner myObj3 = new Scanner(System.in);
      if (high <= low) { 
          System.out.println("Did you like " + item + " more than " + a.get(low) + "?");
          String answer2 = myObj3.nextLine().toLowerCase(); 
          myObj3.close();
          if(answer2.equals("yes")) {
              return low + 1;
          }
          return low;
      }

      int mid = (low + high)/2; 

      if(item == a.get(mid)) {
          myObj3.close();
          return mid+1; 
      }

      System.out.println("Did you like " + item + " more than " + a.get(mid) + "?");
      String answer2 = "";
      if(myObj3.hasNextLine()){
          answer2 = myObj3.nextLine().toLowerCase(); 
      }
      myObj3.close();
      if(answer2.equals("yes")) { 
          return binarySearch(a, item, mid+1, high); 
      }
      return binarySearch(a, item, low, mid-1); 
  } 
}

请忽略不良的命名约定，以及该名称可能尚未达到预期功能的事实。现在，我只是想修复此扫描仪不起作用。

Answer 1

我不确定您的最终目标是什么，但是我可以通过以下方法解决您的错误：

import java.io.*;
import java.util.ArrayList;
import java.util.Scanner;
public class Rater
{
    static Scanner myObj = new Scanner(System.in);

    public static void main(String[] args)throws Exception
    {
        File file = new File("C:\\Users\\hparekh\\OneDrive - Visa Inc\\Documents\\test.txt");

        BufferedReader br = new BufferedReader(new FileReader(file));

        String st;
        ArrayList<String> movList = new ArrayList<String>();
        while ((st = br.readLine()) != null) {
            movList.add(st);
        }
        br.close();
        while(true) {
            System.out.println("Enter a movie to add.");
            String userName = myObj.nextLine();
            int index = binarySearch(movList, userName, 0, movList.size()-1);
            movList.add(index, userName);
        }
    }

    static int binarySearch(ArrayList<String> a, String item, int low, int high)
    {
        if (high <= low) {
            System.out.println("Did you like " + item + " more than " + a.get(low) + "?");
            String answer2 = myObj.nextLine().toLowerCase();
            if(answer2.equals("yes")) {
                return low + 1;
            }
            return low;
        }

        int mid = (low + high)/2;

        if(item == a.get(mid)) {
            return mid+1;
        }

        System.out.println("Did you like " + item + " more than " + a.get(mid) + "?");
        String answer2 = "";
        if(myObj.hasNextLine()){
            answer2 = myObj.nextLine().toLowerCase();
        }
        if(answer2.equals("yes")) {
            return binarySearch(a, item, mid+1, high);
        }
        return binarySearch(a, item, low, mid-1);
    }
}

希望这会有所帮助。祝你好运。

NoSuchElementException：使用扫描仪获取用户输入时找不到行？

1 个答案: