如果數字超出范圍，如果語句提示用戶出現錯誤消息，我如何獲取Java

Question

我是新手，正在做作業，條件如下：-使用條件語句檢查成績是否超出0-101的范圍並顯示錯誤消息。 -否則，如果等級在0-101范圍內，則將等級添加到總計中，並得出等級的平均值。 我有下面的代碼，它工作正常，但是當我輸入0-101范圍以外的數字時，不會出現錯誤消息。 誰能幫助我解決我做錯的事情，感謝您的幫助。 這是我的代碼：import java.util.Scanner;

public class GradeCalculator {
    public  void readGrade() {


         // 1. Creatin a Scanner using the InputStream available.
        Scanner keyboard = new Scanner( System.in );
        // 2. Using the Scanner to read int from the user.
        // 3. returns the next double.


        }
    public void WorkOutGrade(){
         Scanner keyboard = new Scanner(System.in);
         //declaring the variables.
                int testScoreA;
                int testScoreB;
                int testScoreC;
                int testScoreD;
                int testScoreE;
                double sum;
               double average;
              //
         do{
            System.out.println("welcome to the grade calculator , please Enter a grade between 0-101 ");
            System.out.print("And press enter key on your keyboard to type the next score, ");
            System.out.println("please Enter your first test score: ");
            testScoreA = keyboard.nextInt();
          if (testScoreA >= 0 && testScoreA  < 101   );
         else if (testScoreA < 0 && testScoreA  > 101  )

            System.out.print("wront input ");
            System.out.print("Enter your second test score: ");
            testScoreB = keyboard.nextInt();
            System.out.print("Enter your third test score: ");
            testScoreC = keyboard.nextInt();
            System.out.print("Enter your fourth test score: ");
            testScoreD = keyboard.nextInt();
            System.out.print("Enter your fifth test score: ");
            testScoreE = keyboard.nextInt();
            keyboard.nextLine();
             sum =(testScoreA+testScoreB+ testScoreC+ testScoreD+ testScoreE/2);
            average=sum/4;
            System.out.println(" your grades are: "+" grade 1 = "+testScoreA+ 
                    " grade 2 = " +testScoreB+ " grade 3 = "+ testScoreC+ " grade 4 = "+ testScoreD+ " grade 5 = "+ testScoreE);
            System.out.println("your grade average is :"+ average+".");
           } while (testScoreA >= 0 && testScoreA  < 101   );
          if (testScoreA < 0 && testScoreA  > 101  )
            System.out.print("wront input ");
         else  System.out.println(); 

          keyboard.close();
         }

}

Answer 1

對於錯誤情況，應使用or或代替and：

所以代替：

else if (testScoreA < 0 && testScoreA  > 101  )

您應該使用：

else if (testScoreA < 0 || testScoreA  > 101  )

在第一行中，您正在檢查小於0且大於101的數字。據我所知，這是不可能的。 因此，如果您使用or或（||），則將檢查該數字是小於0還是大於101

Answer 2

這是一個示例，其中您閱讀了5個成績（如果它們不正確，請重復）並打印平均值：

import java.util.Scanner;

public class GradeCalculator {



//Maximum number of grades
    private static final int NUM_SCORES = 5;
    public void readGrade() {

        Scanner keyboard = new Scanner(System.in);
        // declaring the variables.
        int sum = 0;

        System.out.println("Welcome to the grade calculator , please Enter a grade between 0-101 ");
        System.out.println("And press enter key on your keyboard to type the next score:");

        for (int i = 0; i < NUM_SCORES; i++) {
            int testScore;
            do {
                System.out.println("Please enter your test score:");
                testScore = keyboard.nextInt();
                //if the score is not correct: Output Error
                if (testScore < 0 || testScore > 101)
                    System.err.println("Wront input. Inpute the test score again!");
                else{
                    //if the score is correct, then add the score to the sum
                    sum += testScore;
                }
                //repeat if the score is not correct, to get a correct score
            }while (testScore < 0 || testScore > 101);
        }
        //The average is the sum of the scores divided by the number of scores
        System.out.println("Your grade average is :" + sum/NUM_SCORES);

        keyboard.close();
    }

    public static void main(String[] args) {

        new GradeCalculator().readGrade();

    }
}