如何只顯示成績

我將無效成績設為“”，但在輸出中似乎顯示了這樣的空間https://i.stack.imgur.com/3kHZW.png如何僅顯示有效成績？無效的成績在輸出中產生空白

這是問題https://i.stack.imgur.com/uxLhG.png

這是所需的輸出https://i.stack.imgur.com/HNZpZ.png

這是我的程式

String [][] student = new String[100][3];
int stu = 0, totalp=0, totalf=0;

for(int h=0; h<100; h  ) {
    System.out.print("Enter Name: ");
    student[h][0] = sc.nextLine();
    System.out.print("Enter Grade: ");
    student[h][1] = sc.nextLine();

    int grade = Integer.parseInt(student[h][1]);
    if(grade >100 || grade <50) {
        student[h][0] = "";
        student[h][1] = "";
        student[h][2] = "";
        System.out.println("Invalid Grade");
    }
    else if(grade >=75) {
        student[h][2] = ("Passed");
        totalp  ;
    }
    else if(grade <=74) {
        student[h][2] = ("Failed");
        totalf  ;
    }
    System.out.print("Add new record (Y/N)?: ");
    char choice = sc.nextLine().charAt(0);
    System.out.println("");
    if(choice == 'y' || choice =='Y') {
        stu  ;
        continue;
    }
    else if(choice == 'n' ||choice =='N') {
        break;
    }
}
System.out.println("\nGRADE SUMMARY REPORT");
System.out.println("\nName\tGrades\tRemarks");
for(int i =0; i<stu 1; i  ) {
    for(int h =0; h<student[i].length; h  ) {
        System.out.print(student[i][h]   "\t");
    }
    System.out.println();
}
System.out.println("\nTotal Passed: "   totalp);
System.out.println("Total Failed: "  totalf);

uj5u.com熱心網友回復：

如果用戶輸入的成績無效，請不要將其添加到student陣列中。然后它根本不會被列印出來。您還應該處理用戶在要求輸入成績時沒有輸入數字的情況。

當詢問用戶是否要添加新記錄時，您只需檢查她是否輸入了Y. 其他任何事情都可以被認為是no。

下面的代碼使用方法printf來格式化報告。此外，為了格式化報告，我會跟蹤用戶輸入的最長名稱。

import java.util.Scanner;

public class Students {
    private static final int MAX_ROWS = 100;
    private static final int NAME = 0;
    private static final int GRADE = 1;
    private static final int REMARK = 2;

    public static void main(String args[]) {
        Scanner sc = new Scanner(System.in);
        String[][] student = new String[MAX_ROWS][3];
        int totalp = 0, totalf = 0, longest = 0;
        int h = 0;
        while (h < MAX_ROWS) {
            System.out.print("Enter Name: ");
            String name = sc.nextLine();
            int len = name.length();
            if (len > longest) {
                longest = len;
            }
            System.out.print("Enter Grade: ");
            String grade = sc.nextLine();
            try {
                int mark = Integer.parseInt(grade);
                if (mark >= 50  &&  mark <= 100) {
                    student[h][NAME] = name;
                    student[h][GRADE] = grade;
                    if (mark >= 75) {
                        student[h][REMARK] = "Passed";
                        totalp  ;
                    }
                    else {
                        student[h][REMARK] = "Failed";
                        totalf  ;
                    }
                    h  ;
                    if (h == MAX_ROWS) {
                        System.out.println("Maximum students entered.");
                    }
                    else {
                        System.out.print("Add new record (Y/N)?: ");
                        String choice = sc.nextLine();
                        if (!"Y".equalsIgnoreCase(choice)) {
                            break;
                        }
                    }
                }
                else {
                    throw new NumberFormatException();
                }
            }
            catch (NumberFormatException xNumberFormat) {
                System.out.println("Invalid. Grade is a number between 50 and 100.");
            }
            System.out.println();
        }
        System.out.println("\nGRADE SUMMARY REPORT\n");
        if (longest < 4) {
            longest = 4;;
        }
        System.out.printf("%-"   longest   "s", "Name");
        System.out.println("   Grade  Remarks");
        String format = "%-"   longest   "s  %4s    %s%n";
        for (int i = 0; i < h; i  ) {
            System.out.printf(format, student[i][NAME], student[i][GRADE], student[i][REMARK]);
        }
        System.out.println();
        System.out.println("Total passed: "   totalp);
        System.out.println("Total failed: "   totalf);
    }
}

這是上述代碼的示例運行的輸出：

Enter Name: Superman
Enter Grade: 99
Add new record (Y/N)?: y

Enter Name: Batman
Enter Grade: 23
Invalid. Grade is a number between 50 and 100.

Enter Name: Iron Man
Enter Grade: 74
Add new record (Y/N)?: n

GRADE SUMMARY REPORT

Name       Grade  Remarks
Superman    99    Passed
Iron Man    74    Failed

Total passed: 1
Total failed: 1

您可能還想參考Oracle 的 Java 教程中的例外課程。

uj5u.com熱心網友回復：

現在您仍在一行中列印無效成績。您想要的是在列印之前檢查并確保等級有效。由于您將所有無效成績都設為空字串，因此您可以像這樣簡單地檢查

if(!student[i][h].isEmpty()){
  System.out.print(student[i][h]   "\t");
}                   

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