收到此錯誤--java.util.NoSuchElementException: No line found- on line 20,27, and 34

Question

如何修復此錯誤？

java.util.NoSuchElementException：找不到行。

我查看了其他類似的帖子，但無法弄清楚如何處理該解決方案。 它看起來（對我來說）就像每個 sc.nextLine(); 有一條對應的線。

重要代碼在下面對不起，對於錯誤的理解/理解。 這是我第一次來這里，我剛開始接觸編程。

package assignment2;
import java.util.Scanner;

public class StringToolsTester {

   public static void main(String[] args) {
       StringTools obj = new StringTools();
       
       
       //Method to get the reverse of the users string input
       Scanner s = new Scanner(System.in);
       System.out.print("reverse - Enter Any String: ");
       String z = s.nextLine();
       System.out.println("Reversed String: "+obj.reverse(z));
       s.close();
       
       //Method to get initials of the users string input
       Scanner a = new Scanner(System.in);
       System.out.print("initials - Enter Full Name: ");
       String initial = a.nextLine();
       System.out.println("Initials: "+obj.initials(initial));
       a.close();
      
       //Method to get the most frequent character from the users string input
       Scanner b = new Scanner(System.in);
       System.out.print("mostFrequent - Enter String: ");
       String most = b.nextLine();
       System.out.println("Most frequent character = "+obj.mostFrequent(most));
       b.close();
      
       //Method to get the binary equivalent of the users binary string input
       Scanner c = new Scanner(System.in);
       System.out.print("binaryToDecimal - Enter Binary: ");
       String str = c.nextLine();
       System.out.println(StringTools.binaryToDecimal(str));
       c.close();