Question

我终于编写了我的程序（花了一段时间，因为我是初学者），程序的作用是：

使用2个选项打印菜单，平均成绩或退出。
如果用户选择平均成绩，则会询问他们的姓名。然后它会告诉他们成绩的平均顺序。
然后他们输入任意数量的成绩，然后按-1，它将为您提供这些成绩和平均成绩的总和。它做了3次，用于家庭作业，测验和测试。

我需要做的最后一件事是平均所有3个等级，然后输出：

System.out.println( name, "'s average is ", + averageFinal );

我从作业中获得了这一行：

Final Average = 0.25*HomeworkAvg + 0.25*QuizAvg + 0.50*TestAvg = 77.87

我尝试将该程序放入：

averageFinal = 0.25*averageOne + 0.25*averageTwo + 0.50*averageThree;

但由于某种原因，我得到了这个奇怪的编译错误，我似乎无法修复：

Assignment3.java:120: error: cannot find symbol
System.println( name, "'s final average is ", averageFinal );
       ^
symbol:   method println(String,String,double)
location: class System
1 error

我的代码只是一个简单的问题，还是我必须在我的字符串方法中更改某些内容？

import java.util.Scanner;

public class Assignment3 {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);

        int choice;
        int total;
        double averageOne;
        double averageTwo;
        double averageThree;
        double averageFinal;
        int grade;

        int gradeCounterone;
        int gradeCountertwo;
        int gradeCounterthree;

        gradeCounterone = 0;
        gradeCountertwo = 0;
        gradeCounterthree = 0;
        total = 0;

        String name;

        System.out.println("Enter 1 or 2: \n 1 - Average grades \n 2 - Quit");
        choice = input.nextInt();

        if (choice == 1) {
            System.out.println("Enter the students name:");
            name = input.next();

            System.out.println("Grades will be entered in this order: \n 1) Homework Grades \n 2) Quiz Grades \n 3) Test Grades ");

            {
                System.out.println("Enter homework grades, press -1 when finished:");
                grade = input.nextInt();

                while (grade != -1) {
                    total = total + grade;
                    gradeCounterone = gradeCounterone + 1;

                    System.out.println("Enter homework grades, press -1 when finished:");
                    grade = input.nextInt();

                }
                if (gradeCounterone != 0) {
                    averageOne = (double) total / gradeCounterone;

                    System.out.printf("\nThe total of the %d homework grades is %d\n", gradeCounterone, total);
                    System.out.printf("\nThe average of the homework grades is %.2f\n ", averageOne);

                }

                // second loop for quiz grades

                System.out.println("\nEnter quiz grades, press -1 when finished:");
                grade = input.nextInt();

                while (grade != -1) {
                    total = total + grade;
                    gradeCountertwo = gradeCountertwo + 1;

                    System.out.println("Enter quiz grades, press -1 when finished:");
                    grade = input.nextInt();

                }
                if (gradeCountertwo != 0) {

                    averageTwo = (double) total / gradeCountertwo;

                    System.out.printf("\nThe total of the %d quiz grades is %d\n", gradeCountertwo, total);
                    System.out.printf("\nThe average of the quiz grades is %.2f\n ", averageTwo);

                }

                // third loop for test grades

                System.out.println("\nEnter test grades, press -1 when finished:");
                grade = input.nextInt();

                while (grade != -1) {
                    total = total + grade;
                    gradeCounterthree = gradeCounterthree + 1;

                    System.out.println("Enter test grades, press -1 when finished:");
                    grade = input.nextInt();

                }
                if (gradeCounterthree != 0) {

                    averageThree = (double) total / gradeCounterthree;

                    System.out.printf("\nThe total of the %d test grades is %d\n", gradeCounterthree, total);
                    System.out.printf("\nThe average of the test grades is %.2f\n ", averageThree);

                }

                averageFinal = 0.25 * averageOne + 0.25 * averageTwo + 0.50 * averageThree;
                System.println(name, "'s final average is ", averageFinal);

            }

        } else if (choice == 2) {
            System.out.println("Exiting program.");
        } else {
            System.out.println("Invalid response, exiting program.");
        }
    }
}

Answer 1

应该是：

System.out.println( name + " s final average is " + averageFinal );

而不是

System.println( name, "' s final average is ", averageFinal );

Answer 2

而不是

System.println( name, "'s final average is ", averageFinal );

试

System.out.println( name + "'s final average is " + averageFinal );

您也可以从JDK文档中获取此信息。

Answer 3

这是一个错字。

它不是

System.println();

这是

System.out.println();

请参阅此link

Answer 4

这里有几个问题。

尽管显而易见：它是System.out.println。并且，您将String与+：

连接在一起

System.out.println(name + "'s final average is " + averageFinal);

现在，在您修复该代码之后，您会得到这些变量未被初始化的问题：

averageFinal = 0.25 * averageOne + 0.25 * averageTwo + 0.50 * averageThree;

通过程序的自然流程，averageOne，averageTwo和averageThree都无法保证初始化 - 似乎它们正在某些if后面进行初始化语句。

将它们初始化为零是直截了当的，以防你没有点击任何if语句：

double averageOne = 0;
double averageTwo = 0;
double averageThree = 0;

简单的平均错误，找不到合适的代码

4 个答案: