“线程中的异常”；“主要”；当读取文本文件时，java.util.NoSuchElementException扫描仪

我试图在我的程序中实现扫描器在文本文件中搜索，直到找到一行与其搜索的字符串相同的内容。 我不断得到以下错误：

Exception in thread "main" java.util.NoSuchElementException
    at java.util.Scanner.throwFor(Scanner.java:862)
    at java.util.Scanner.next(Scanner.java:1371)
    at hangman.HangmanArr.<init>(HangmanArr.java:62)
    at hangman.HangmanApp.main(HangmanApp.java:18)

课程的完整代码是：

package hangman;

import java.io.*;
import javax.swing.*;
import java.util.*;

/**
 *
 * @author ghost
 */
public class HangmanArr {

    String letter;
    int x = 0;
    String word;
    String dashWord;
    String newWord;
    String username;
    String password;
    private Hangman[] arrUsers = new Hangman[100];

    public HangmanArr() {
        JOptionPane.showInputDialog(null, "The aim of Hangman is to form "
                + "a word \nby guessing individual letters \nof the word "
                + "before a"
                + " hanging man \nand gallows are built. Every letter\n "
                + "that is entered "
                + "which does not \nappear in the word will contribute to "
                + "\nthe hanging"
                + " man and gallows; by adding \na single component to "
                + "drawing – \nif the hanging "
                + "man and gallows are \ncomplete before guessing the "
                + "complete word;\n you have lost "
                + "the game. Goodluck!" + "\nPress Enter to continue", "H_NGM_N", JOptionPane.INFORMATION_MESSAGE);
        String ans = " ";

        ans = JOptionPane.showInputDialog(null, "Please enter an option of "
                + "your choice\n"
                + "A – login\n"
                + "B - Sign up\n"
                + "C - Scoreboard\n"
                + "D - quit", "Menu A", JOptionPane.QUESTION_MESSAGE).toUpperCase();

        if (ans.equals("A")) {
            username = JOptionPane.showInputDialog(null, "Enter usesrname:", "Login 1/2", JOptionPane.QUESTION_MESSAGE);

            try {
                Scanner scFile = new Scanner(new File("TextFileB.txt"));

                String line = scFile.nextLine();
                int flse = 0;
                String user = " ";

                while (scFile.hasNext() || flse == 0) {
                    line = scFile.nextLine();
                    Scanner scLine = new Scanner(line).useDelimiter("#"); 
                    user = scFile.next();
                    if (user.equals(username)) {
                        password = JOptionPane.showInputDialog(null, "Welcome " + username + ". \n Please enter your password to play", "Login 2/2", JOptionPane.QUESTION_MESSAGE);
                        flse++;

                    }

                }
                scFile.close();

            } catch (IOException i) {
                System.out.println("Text File could not be found");
            }
        }


        if (ans.equals("B")) {
            username = JOptionPane.showInputDialog(null, "Enter usesrname:", "Sign Up 1/2", JOptionPane.QUESTION_MESSAGE);
            password = JOptionPane.showInputDialog(null, "Welcome " + username + ". \n Please enter your password to play", "Sign Up 2/2", JOptionPane.QUESTION_MESSAGE);
            File add = new File("TextFileB.txt");
            try {
                PrintWriter fw = new PrintWriter(new FileWriter(add, true));
                fw.write(username + "#" + password + "#");
                fw.println();
                fw.close();
            } catch (IOException e) {
                System.out.println("Could not locate text file to store data");
            }
        }
    }
}

---

您的

while

状况有问题

如果到达文件末尾时没有找到用户名，

flse

的值仍然是

0

，因此循环条件将被评估为

true

，这意味着您将到达

scFile.nextLine（）

调用，该调用将导致一个

NoTouchElementException

，因为您已到达文件末尾

您必须将该条件更改为：

scFile.hasNext() && flse == 0

---

你是说

user=scFile.next（）

将成为

user=scLine.next（）

？现在我不知道你在哪里使用它，如果你调用

scFile.next

两次，每次都不检查，你可能会遇到I/O错误。要检查的代码是什么？这是我修改过的代码：你能替换

user=scLine.next（）

看看它是否有效吗？

scFile.hasNext() && flse == 0