Question

我有一个程序，允许用户输入他们希望分配成绩的学生数量的数字。然后，它打印出哪个学生不在总数中（例如6个中的1个），然后提示用户输入他们的名字和分数。

我正常工作的分数但是当显示最终消息时，我无法获得最大名称和第二个最大名称来显示任何内容。

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

有人可以告诉我为什么会这样吗？

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

几个问题。

1）else-if不是必需的。你可以（现在已经）＆＃34;降级＆＃34;第一个if语句中的当前最大值到第二个max。

2）你做这个操作的顺序是错误的。这里的评论突出了这个问题。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）初学者错误，但您在使用扫描仪时没有正常工作，正如我在评论中所讨论的那样。

您是否注意到您正在进行System.out.println(name);，但该名称未被打印？这是因为String name = stdin.nextLine();实际上是在先前输入的数字后读取换行符，然后以下stdin.nextLine()实际读取您输入的名称。

所以，你需要像这样补偿新线

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

首先，始终将最大值分配给Integer.MIN_VALUE，然后才进行比较。

您的If语句中存在问题

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

交换这两行并且它应该工作：你一直用MaxName覆盖secondMaxName。将其更改为

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

代码中的逻辑错误如下：

如果学生1是sree并且得分是20：如果条件 MaxName = Sree和secondMaxName = sree ..这适用于第一次迭代

迭代2：学生2是saha得分是40：在你的if条件下 MaxName是Saha，现在您将MaxName分配给secondMaxName，后者也变为Saha而不是sree

清楚？

扫描仪无法正常工作

2 个答案: