遍歷二維數組的第一列后僅打印一次消息

Question

導入 java.util.Scanner;

公開課成績{

public static void main(String[] args) {

    String students[][] = new String[2][4];

    Scanner input = new Scanner(System.in);

    for (int i = 0; i < 2; i++) {

        System.out.print("\n\nStudent 00" + (i + 1) + "\n\n");

        for (int j = 0; j < 4; j++) {

            if (j == 0) {
                System.out.print("\n\tStudent Code : ");
            } else if (j == 1) {
                System.out.print("\n\tName : ");
            } else if (j == 2) {
                System.out.print("\n\tMaths Grade : ");
            } else if (j == 3) {
                System.out.print("\n\tFrench Grade : ");
            } else {
                System.out.print("\n\tNonexistent field!\n");
            }

            students[i][j] = input.nextLine();
        }

    }

    System.out.print("\n\tRegistered Students : \n\n");

    System.out.print("\tCODE\tFULL NAME\tMATHS\tFRENCH\n\n");

    for (int i = 0; i < 2; i++) {

        for (int j = 0; j < 4; j++) {

            System.out.print("\t" + students[i][j] + "  ");

        }

        System.out.println();
    }

//索取學生代碼。

    System.out.print("\n\tStudent Code : ");

    String search= input.nextLine();

    boolean found = false;

    for (int i = 0; i < 2; i++) {

        for (int j = 0; j < 4; j++) {

// 發現 = 真;

            if (search.equals(students[i][0])) {

                found = true;

                System.out.print("\n\tStudent Code Found!\n");

                String math = students[i][2];
                String french = students[i][3];

                Double m = new Double(math);
                double mathConv = m.doubleValue();

                Double f = new Double(french);
                double frenchConv = f.doubleValue();

                double average = (mathConv + frenchConv) / 2;

                System.out.print("\n\tMoyenne de l'etudiant : " + average + "\n");

                if (average <= 40) {

                    System.out.print("\n\tFailure!\n");

                } else if (average > 40 && average < 70) {

                    System.out.print("\n\tReprisal!\n");

                } else {

                    System.out.print("\n\tSuccess!\n");
                }

            }

            else if (!search.equals(students[i][0])) {

                found = false;

                System.out.print("\n\tCode incorrect!\n");

            }

        }
    }
}

}

輸入代碼 etudiant 后，我​​只需要顯示一條消息，但它會顯示該消息 4 次。 循環應該只遍歷每一行的第一列，並將其與用戶輸入的內容進行比較。

Answer 1

改變這個：

for (int j = 0; j < 4; j++)

對此：

for (int j = 0; j < 1; j++)

因為我們只想運行該循環一次。

或者，您可以完全刪除 j 循環。

Answer 2

當您迭代搜索時，您不需要第二個循環來迭代屬性，因為您不使用它

 System.out.print("\n\tStudent Code : ");
 String search = input.nextLine();
 boolean found = false;

 for (int i = 0; i < 2; i++) {
//        for (int j = 0; j < 4; j++) { //you don't need this loop

Answer 3

建議您對這些數組使用 length 參數，這樣如果您更改大小，循環就不會中斷，在這種情況下，您只需獲取數組的第一個元素，然后遍歷它即可。 所以而不是

for (int i = 0; i < 2; i++) {

        System.out.print("\n\nStudent 00" + (i + 1) + "\n\n");

        for (int j = 0; j < 4; j++) {

            if (j == 0) {
                System.out.print("\n\tStudent Code : ");
            } else if (j == 1) {
                System.out.print("\n\tName : ");
            } else if (j == 2) {
                System.out.print("\n\tMaths Grade : ");
            } else if (j == 3) {
                System.out.print("\n\tFrench Grade : ");
            } else {
                System.out.print("\n\tNonexistent field!\n");
            }

            students[i][j] = input.nextLine();
        }

    }

你可以說

        System.out.print("\n\nStudent 001" + "\n\n");

        for (int j = 0; j < students[0].length; j++) {

            if (j == 0) {
                System.out.print("\n\tStudent Code : ");
            } else if (j == 1) {
                System.out.print("\n\tName : ");
            } else if (j == 2) {
                System.out.print("\n\tMaths Grade : ");
            } else if (j == 3) {
                System.out.print("\n\tFrench Grade : ");
            } else {
                System.out.print("\n\tNonexistent field!\n");
            }

            students[0][j] = input.nextLine();
        }