扫描仪工作不正常

Question

我有一个程序，允许用户输入一个数字的学生数量，他们希望分配一个等级。然后，它打印出哪一个学生在总数中（例如6个中的1个），然后提示用户输入他们的名字和分数。

我的分数工作正确，但当最后的消息显示，我不能得到最大名称和第二个最大名称显示任何东西。

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

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

很少问题。

1）else-if不是必需的。您可以（并且已经）将当前max“降级”为第一个if语句中的第二个max。

2）您执行该操作的顺序有误。此处的注释突出了该问题。您已通过相等的传递属性将secondmaxname设置为name。

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

您可以通过简单的重新排序来解决这个问题。

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

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

3）初学者的错误，但你的扫描仪没有正常工作，正如我在评论中所讨论的。

是否注意到您正在执行system.out.println（name）；，但未打印名称？这是因为字符串name=stdin.nextline()；实际上读取的是前面输入的数字后面的换行符，那么下面的stdin.nextline()实际上读取的是您输入的名称。

因此，您需要像这样补偿新线路

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");