Question

好的，所以我已经构建了这个程序来读取成绩的文本文件并显示前两名学生。我应该在成绩中显示任何关系，我开始工作。但是，如果文本文件中没有关联，则显示重复的第二高分。我似乎无法使它工作，所以如果没有关系，它会显示两个最高等级，如果有关系显示两个关系。我真的需要帮助。我一直在努力争取这么做几个小时，我必须在今晚睡觉前提交这个。请有人帮我修复这段代码，这是一个非常好的成绩，我无法弄明白。

package lab06;

import java.util.*;
import java.io.*;
public class Lab06 {


public static void main(String[] args) throws Exception {
    Scanner lab06txt = new Scanner(new File("Lab06.txt")); //declare scanner for lab06.txt        
    //declare variables
    int grade = 0;
    int grade2 = 0;
    int record = 0;       
    int Highest = 0;
    int Highest2 = 0;
    int ACounter = 0;
    int BCounter = 0;
    int CCounter = 0;
    int DCounter = 0;
    int FCounter = 0;
    double average = 0;
    String lastName = "";
    String lastNameHigh = "";
    String lastNameHigh2 = "";
    String firstName = "";
    String firstNameHigh = "";
    String firstNameHigh2 = "";

    //while loop for lab06txt
    while (lab06txt.hasNext()){
        record ++; //keep track of number of records
        lastName = lab06txt.next(); //next string is placed into lastName
        firstName = lab06txt.next(); //next string is placed into firstName
        grade = lab06txt.nextInt(); //next integer is placed into grade
        {
            average += grade; //accumulate variable grade into variable average
            if (grade >= Highest) //if statement for determining highest grade 
            {
                Highest = grade;
                firstNameHigh = firstName; //places firstName of highest grade record into firstNameHigh
                lastNameHigh = lastName; //places lastName of highest grade record into lastNameHigh
            }                                       
        }

        {
        if ((grade >= 90) && (grade <= 100)) //if statements for variable grade
        {
           ACounter++;       //increases Acounter by 1
        }
        if ((grade >= 80) && (grade <= 89))
        {
           BCounter++;         //increases Bcounter by 1
        }
        if ((grade >= 70) && (grade <= 79))
        {
           CCounter++;         //increases Ccounter by 1
        }
        if ((grade >= 60) && (grade <= 69))
        {
           DCounter++;         //increases Dcounter by 1
        }
        if ((grade < 60))
        {
           FCounter++;         //increases Fcounter by 1
        }
        if ((grade < 0) || (grade > 100)) 
        {
            //if an incorrect error is found in the loop display the faulty record and end the program
            System.out.print("Score is out of bounds in record " + record + ": " + lastName + " "+ firstName + " " + grade + ".\nProgram ending\n"); 
            return;

        }
       }
    }
    Scanner SecondHighest = new Scanner(new File("Lab06.txt")); //new scanner for second highest grade
    while(SecondHighest.hasNext()) 
    {
        lastName = SecondHighest.next(); 
        firstName = SecondHighest.next();
        grade2 = SecondHighest.nextInt();           
        if(grade2 > Highest2 && grade2 < Highest) //if statement to determine second highest grade
        {
                Highest2 = grade2;
                firstNameHigh2 = firstName;
                lastNameHigh2 = lastName; 
        }
        if (Highest == grade2){
            Highest2 = grade2;
            firstNameHigh2 = firstName;
            lastNameHigh2 = lastName;
        }
    }

    System.out.println("Total students in class:        " +record); //display total students in class
    System.out.printf("Class average:                 %.1f\n", average/record); //display class average
    System.out.println("Grade Counters: "); 
    System.out.println("A's     B's     C's     D's     F's");
    System.out.printf(ACounter + "%7d %7d %8d %7d\n", BCounter,CCounter,DCounter,FCounter); //display number of A's B's C's D's and F's
    System.out.print("\n");
    System.out.println("Top Two Students: \n"); 

    System.out.printf(lastNameHigh + " " + firstNameHigh + "%15d \n", Highest); //display highest score and student
    System.out.printf(lastNameHigh2 + " " + firstNameHigh2 + "%15d\n", Highest2); //display second highest score and student


}

}

文本文件的内容遵循以下格式：

Jackson Nicholas    96
James   Kevin       67
Jansen  David       92
Johnson Charlene    69
Jones   Nicole      83
Klein   Harry       97

Answer 1

尽管您应该对代码进行清理，但这个块似乎...... 奇数。

while(SecondHighest.hasNext()) 
    {
        lastName = SecondHighest.next(); 
        firstName = SecondHighest.next();
        grade2 = SecondHighest.nextInt();           
        if(grade2 > Highest2 && grade2 < Highest) //if statement to determine second highest grade
        {
                Highest2 = grade2;
                firstNameHigh2 = firstName;
                lastNameHigh2 = lastName; 
        }
        if (Highest == grade2){
            Highest2 = grade2;
            firstNameHigh2 = firstName;
            lastNameHigh2 = lastName;
        }
    }

特别是第二个if语句：它读取，“如果最高等于grade2，那么我们用grade2覆盖highest2，firstNameHigh2用firstName覆盖，lastNameHigh2用lastName覆盖。”

为什么我们需要那个？我们在上面的陈述中做了同样的工作。删除它。

现在你离开了：

while(SecondHighest.hasNext())  {
    lastName = SecondHighest.next(); 
    firstName = SecondHighest.next();
    grade2 = SecondHighest.nextInt();           
    if(grade2 > Highest2 && grade2 < Highest) {
        Highest2 = grade2;
        firstNameHigh2 = firstName;
        lastNameHigh2 = lastName; 
    }
}

这似乎有效 - 我让杰克逊尼古拉斯和克莱恩哈利成为你的前两名学生。但它是否涵盖了相同分数的情况？

为了测试这个案例，我在你的名单上包括了另一名学生：火影忍者Uzumaki得分为97.这将确保最高的两个是Klein Harry和Naruto Uzumaki。

我再次运行它，我将火影忍者Uzumaki和杰克逊尼古拉斯作为我的前两名学生。那是不可能的 - 有两个学生得分平分！

我需要在if语句中添加等价检查 - grade2应大于或等于 Highest2，而grade2应小于或等于最高到确定第二高分。

现在，有趣的部分是阻止一个名字挤压另一个名字。我将此作为练习留给读者，但确切地说，您的数据布局方式，我读到的第一个名称不能与我读到的高分名字相同，或者是同一个人。

现在，只要有办法看两个字符串是否相等......

当然，这样做会让你的代码变得脆弱，两个名为“Jon”的用户（我和他们三个人一起工作，所以这会使硬核失败） - 但也许它应该是姓氏。想一想 - 这对读者来说是一种练习。

if项目的语句和循环

1 个答案: