Question

问题：如果marksObtained低于35

，仍然会获得B级

在数据库中存储一个描述评分系统的数组

不能使用switch-case ，因为不同的类会有不同的评分系统

String[] gradeDetails = {A,60,100,
                         B,45,59.99,
                         C,35,44.99,
                         D,0,34.99};

推断成绩的逻辑是

int j=0;
while (j<gradeDetails.length/3){
    grade = gradeDetails[j++];
    min = Float.parseFloat(gradeDetails[j++]);
    max = Float.parseFloat(gradeDetails[j++]);
    if(marksObtained >= min && marksObtained <= max)
        break;
}

的解决

只是为不同的增量使用了不同的变量

j=0;
k=0;
while (k<gradeDetails.length/3){
    grade = gradeDetails[j++];
    min = Float.parseFloat(gradeDetails[j++]);
    max = Float.parseFloat(gradeDetails[j++]);
    if(marksObtained >= min && marksObtained <= max)
        break;
    k++;
}

没想到解决方案就这么傻了。 全部谢谢

Answer 1

gradeDetails.length = 12 =＆gt; gradeDetails.length/3将为4

while (j<gradeDetails.length/3){
    grade = gradeDetails[j++];    // A -> j=0 , B -> j = 4 loop will end
    min = Float.parseFloat(gradeDetails[j++]);
    max = Float.parseFloat(gradeDetails[j++]);
    if(marksObtained >= min && marksObtained <= max)
        break;
}

所以B只是不制动循环条件的最后一次迭代。你可以试试这个：

while (j<gradeDetails.length){
    grade = gradeDetails[j++];    
    min = Float.parseFloat(gradeDetails[j++]);
    max = Float.parseFloat(gradeDetails[j++]);
    if(marksObtained >= min && marksObtained <= max)
        break;
}

OR

while (j<gradeDetails.length/3){
    grade = gradeDetails[j*3];
    min = Float.parseFloat(gradeDetails[j*3+1]);
    max = Float.parseFloat(gradeDetails[j*3+2]);
    j++;
    if(marksObtained >= min && marksObtained <= max)
        break;
}

或者您可以使用2D阵列

或者您可以使用包含mark，min和max。

的类

Answer 2

问题在于你的while表达式。 j每个循环增加3（因为你执行j++三次）。所以在第二个循环之后，它等于5，这比长度除以3（4）更高，所以你已经不在循环中了。

您应该只使用while j < (gradeDetails.length)

Answer 3

实现你想要的代码......

public static void main(String[] args) {
        String[] gradeDetails = { "A", "60", "100", "B", "45", "59.99", "C", "35", "44.99", "D", "0", "34.99" };
        double marks = 0;
        String grade = "";
        for (int j = 0; j < gradeDetails.length; j++) {
            grade = gradeDetails[j];
            j = j + 1;
            double min = Double.valueOf(gradeDetails[j]);
            j = j + 1;
            double max = Double.valueOf(gradeDetails[j]);
            if (marks >= min && marks <= max)
                break;
        }
        System.out.println("Your grade is :: "+grade);
}

用于从标记中查找成绩的Java代码不正确

3 个答案: