Scanner not working correctly

Question

I have a program which allows the user to enter a number for the amount of students they wish to assign a grade to. Afterwards, it prints out which student that is out of the total (for example 1 of 6) then prompts the user for their name as well as score.

The scores I have working correctly but when the final message is displayed I can't get the max name and second max name to display anything.

Enter the number of students:2 
Student 1 of 2 
Enter Student's name:Noah 
Enter Student's score:100 
Student 2 of 2 
Enter Student's name:Ryan 
Enter Student's score:50 
The highest score was 100.0 and got it 
The second highest score was 50.0 and got it

Could someone please tell me why this is happening?

public class TwoHighestScores {

    public static void main(String[] args) {

        //Declare variables

        // Initialize Scanner
        Scanner stdin = new Scanner(System.in);

        // Enter the number of students
        System.out.print("Enter the number of students:");
        int n = stdin.nextInt();
        double MaxValue = 0.0;
        double secondMax = 0.0;
        String MaxName = " ";
        String secondMaxName = " ";
        int count = 1;

        for (int i = 0; i < n; i++) {
            System.out.println("Student " + count + " of " + n);

            System.out.print("Enter Student's name:");
            String name = stdin.nextLine();
            stdin.nextLine();
            System.out.print(name);

            count++;

            System.out.print("Enter Student's score:");
            double score = stdin.nextDouble();

            // check
            if (score > MaxValue) {
                secondMax = MaxValue;
                MaxName = name;
                secondMaxName = MaxName;
                MaxValue = score;
            } else if (score > secondMax) {
                secondMax = score;
                secondMaxName = name;

            }
        }

        System.out.println("The highest score was " + MaxValue + " and " + MaxName + " got it");
        System.out.println("The second highest score was " + secondMax + " and " + secondMaxName + " got it");

    }
}

Answer 1

Few problems.

1) The else-if is not necessary. You can (and already are) "demote" the current max to the second max within the first if-statement.

2) The ordering you do that operation is wrong. The comments here highlight the issue. You've set secondMaxName to name through the transitive properties of equality.

if (score > MaxValue) {
    secondMax = MaxValue;
    MaxName = name;          // Sets MaxName = name
    secondMaxName = MaxName; // secondMaxName = MaxName = name
    MaxValue = score;
} 

You can fix that with a simple reordering.

if (score > MaxValue) {
    // Demote the current max
    secondMax = MaxValue;
    secondMaxName = MaxName;

    // Assign the new max
    MaxName = name;
    MaxValue = score;
} 

3) Beginner mistake, but your use of the Scanner isn't working correctly, as I was discussing in the comments.

Did you notice that you were doing System.out.println(name);, but the name wasn't being printed? That is because the String name = stdin.nextLine(); is actually reading the newline character after the previously entered number, then the following stdin.nextLine() actually reads the name that you entered.

So, you need to compensate for the new line like so

System.out.print("Enter the number of students: ");
int n = stdin.nextInt();

double MaxValue = 0.0;
double secondMax = 0.0;
String MaxName = " ";
String secondMaxName = " ";

for (int i = 1; i <= n; i++) {
    stdin.nextLine(); // Clear the newline from the Scanner

    System.out.println("Student " + i + " of " + n);

    System.out.print("Enter Student's name:");
    String name = stdin.nextLine();

    System.out.print("Enter Student's score:");
    double score = stdin.nextDouble();

    // check
    if (score > MaxValue) {
        // Demote the current max
        secondMax = MaxValue;
        secondMaxName = MaxName;

        // Assign the new max
        MaxName = name;
        MaxValue = score;
    } 
}

System.out.println("The highest score was " + MaxValue + " and " + MaxName + " got it");
System.out.println("The second highest score was " + secondMax + " and " + secondMaxName + " got it");

Answer 2

First of all, always assign max values to Integer.MIN_VALUE then only do the comparison.

There is a problem in your If statement

if (score > MaxValue){
    secondMax = MaxValue;
    ***MaxName = name;
    secondMaxName = MaxName;***
    MaxValue = score;
    }

Interchange those two lines and it should work: You are overwriting secondMaxName with MaxName all the time. Change it to

if (score > MaxValue){
    secondMax = MaxValue;
    secondMaxName = MaxName;
    MaxName = name;
    MaxValue = score;
    }

The logical bug in your code is as follows:

if student 1 is sree and score is 20: in if condition MaxName = Sree and secondMaxName = sree.. this is fine for first iteration

Iteration2: student 2 is saha score is 40: in your if condition MaxName is Saha, and now you are assigning MaxName to secondMaxName which becomes Saha as well instead of sree

clear?