Question

Write a program that prompts the user to enter the number of students and each student’s name and score, and finally displays the student with the highest score and the student with the second-highest score. Use the next() method in the Scanner class to read a name rather using the nextLine() method.
This is my code , but i get this error Enter the number of students: Exception in thread "main" java.util.InputMismatchException
   at java.util.Scanner.throwFor(Scanner.java:871)
   at java.util.Scanner.next(Scanner.java:1494)
   at java.util.Scanner.nextInt(Scanner.java:2139)
   at java.util.Scanner.nextInt(Scanner.java:2095)
   at Exercise05_09.main(Exercise05_09.java:16)

import java.util.Scanner;

public class Exercise05_09 {
   public static void main(String[] args) {
       // Create a Scanner
       Scanner input = new Scanner(System.in);

       // Prompt the user to enter the number of students
       System.out.print("Enter the number of students: ");
       int numberOfStudents = input.nextInt();

       int score,                    // Holds students' score      
           highest = 0,            // Highest score
           secondHigest = 0;   // Second highest score
       String name = "",        // Holds students' name
               student1 = "",    // Highest scoring student name
               student2 = "";   // Second highest scoring student name
      
       // Prompt the user to enter each students' name and score
       System.out.println("Enter each students' name and score:");
       for (int i = 0; i < numberOfStudents; i++) {
           System.out.print(
               "Student: " + (i + 1) + "\n Name: ");
           name = input.next();
           System.out.print(" Score: ");
           score = input.nextInt();

           if (i == 0) {
               // Make the first student the highest scoring student so far
               highest = score;
               student1 = name;
           }
           else if (i == 1 && score > highest) {
               // Second student entered scored
               // higher than first student
               secondHigest = highest;
               highest = score;
               student2 = student1;
               student1 = name;
           }
           else if (i == 1) {
               // Second student entered scored
               // lower than first student
               secondHigest = score;
               student2 = name;
           }      
           else if (i > 1 && score > highest && score > secondHigest) {
               // Last student entered has the highest score
               secondHigest = highest;
               student2 = student1;
               highest = score;
               student1 = name;
           }
           else if (i > 1 && score > secondHigest) {
               // Last student entered has the second highest score
               student2 = name;
               secondHigest = score;
           }
       }

       // Display the student with the hightest score
       // and the student with the second-hightest score.
       System.out.println(
           "Higest scoring student: " + student1 +
           "\nSecond Higest scoring student: " + student2);
   }
}

Answer 1

Exception in thread "main" java.util.InputMismatchException

This runtime error indicate that there is input mismatch this exception thrown when data type of variable to hold input and data type of input is not matched.

consider the following code line

score = input.nextInt();

here if keyborad input is intger type then there will be no error and if keyborad input is non integer (decimal value) say 45.8 then program get terminated with runtime error because nextInt() throws InputMismatchException if next token is not an Integer.

To resolve the above issue declare variables score, highest, secondHighest as double

and use nextDouble() instead of nextInt() as follow :

score = input.nextDouble();

by using nextDouble we can get integer input and non integer (decimal value) input as well without InputMismatchException.

Currected Code : please refer to the corrected code below

import java.util.Scanner;

public class Exercise05_09 {
   public static void main(String[] args) {
       // Create a Scanner
       Scanner input = new Scanner(System.in);

       // Prompt the user to enter the number of students
       System.out.print("Enter the number of students: ");
       int numberOfStudents = input.nextInt();

       // declare score, highest, secondHigest as double/ 
       double score,                    // Holds students' score      
           highest = 0,            // Highest score
           secondHigest = 0;   // Second highest score
       String name = "",        // Holds students' name
               student1 = "",    // Highest scoring student name
               student2 = "";   // Second highest scoring student name
      
       // Prompt the user to enter each students' name and score
       System.out.println("Enter each students' name and score:");
       for (int i = 0; i < numberOfStudents; i++) {
           System.out.print(
               "Student: " + (i + 1) + "\n Name: ");
           name = input.next();
           System.out.print(" Score: ");
           //score = input.nextInt(); //change this line to below
           score = input.nextDouble();

           if (i == 0) {
               // Make the first student the highest scoring student so far
               highest = score;
               student1 = name;
           }
           else if (i == 1 && score > highest) {
               // Second student entered scored
               // higher than first student
               secondHigest = highest;
               highest = score;
               student2 = student1;
               student1 = name;
           }
           else if (i == 1) {
               // Second student entered scored
               // lower than first student
               secondHigest = score;
               student2 = name;
           }      
           else if (i > 1 && score > highest && score > secondHigest) {
               // Last student entered has the highest score
               secondHigest = highest;
               student2 = student1;
               highest = score;
               student1 = name;
           }
           else if (i > 1 && score > secondHigest) {
               // Last student entered has the second highest score
               student2 = name;
               secondHigest = score;
           }
       }

       // Display the student with the hightest score
       // and the student with the second-hightest score.
       System.out.println(
           "Higest scoring student: " + student1 +
           "\nSecond Higest scoring student: " + student2);
   }
}

Sample Output :

Please refer to the below Screenshot of the code to understand indentation of the code :