Question

我应该：

创建两个构造函数。一个。查询学生的姓名和三个分数。湾拿四个论点
编写计算和设置平均值
写一个方法calculateGrade，根据90 + = A计算，80 + = B，70 + = C，60 + = D，＆lt; 60 = F
编写一个方法toString，显示带有a的gradeReport。名字b。一条线上的三个分数c。平均和字母等级
使用第一个构造函数时，确保分数在0-100之内。如果不再提示并解释原因。
将输出格式化为正好两位小数
格式化输出，以便用标签分隔分数。

我并不是要求所有这一切都完成，但是如果你看看我的代码，你可以给我任何关于我出错的地方以及我可能需要添加的内容吗？

import java.text.DecimalFormat;
import java.util.Scanner;
public class GradeReport 
{
    String name, name1, name2;
    int score1, score2, score3;
    double average;
    char grade;
    public GradeReport()  //creates the first constructor
    {
        Scanner sc = new Scanner (System.in);

        System.out.println ("Enter student's first name: ");
        name1 = sc.nextLine();

        System.out.println ("Enter the student's last name: ");
        name2 = sc.nextLine();

        System.out.println ("Enter first grade: ");
        score1 = sc.nextInt();

        System.out.println ("Enter second grade: ");
        score2 = sc.nextInt();

        System.out.println ("Enter third grade: ");
        score3 = sc.nextInt();
    }
    public GradeReport (String name, int score1, int score2, int score3)
    {
    }
    public void calculateAverage()
    {
        average = ((score1 + score2 + score3) / 3);

        DecimalFormat fmt = new DecimalFormat ("0.###"); //to format average to 2 decimal places
    }
    public void calculateGrade()
    {
        if (average >= 90)
            System.out.println("A");
        else if (average >= 80)
            System.out.println("B");
        else if (average >= 70)
            System.out.println("C");
        else if (average >= 60)
            System.out.println("D");
        else
            System.out.println("F");
    }
    public String toString()
    {
        //System.out.println (name1, name2);
        String gradeReport = Double.toString(score1) + "\t," + Double.toString(score2)+ "\t," + Double.toString(score3);
        //String gradeReport = Double.toString(average);
        return gradeReport;
    }


}

Answer 1

您已注释掉elif个陈述。我想如果你取消注释它们会得到一些编译器错误。在Java中，elif应写为else if。

最后，你的行

  String gradeReport = Double.toString(score1)\t, Double.toString(score2)\t,      Double.toString(score3);

......你到底想要的是什么？我认为你已经意味着：

String gradeReport = Double.toString(score1)+"\t, "+Double.toString(score2)+"\t,      "+Double.toString(score3);

但不清楚......如果是你的意思，这里的学习要点是字符串文字应该用双引号括起来，而+运算符会被重载用于字符串连接（将一个字符串附加到另一个字符串）。

Answer 2

else if条件下也存在逻辑错误。应该是：如果平均值> = 90，否则如果平均值> = 80，否则如果平均值> = 70，否则如果平均值> = 60，则其他。

将public GradeReport()替换为public static void main(String[] args)。尝试将所有代码放在一个方法中 - 主要。该方法将按照您的预期进行分解（重构）它。

Answer 3

从您的作业中，您可以解决以下有关您的代码的问题（对任何语法错误都抱歉，请不要因为我在3年后编写符合条件的Java而无法编写.net）

Class GradeReport{
//The values we get from the user
private string name
private int score1
private int score2
private int score3

//Things we are told we need to calculate at some point
private double average
private char grade

public GradeReport(){
// Get values from the user and validate them

// We will need to assign the values to the fields in some way 
// here...do we have somewhere else to do that already written?
}

public GradeReport(String name, int score1, int score2, int score3){
// We will probably want to assign these parameters to the fields here
}

public void calculateAverage(){
// You already have that pretty much, but you prob don't need to output it to the screen
}

public void calculateGrade(){
//Some sort of if...else logic is needed to work out the grade from the avg
}

public String toString(){
// We need to output our various bit of information here in a nicely formatted String
// I would recommend looking at String.Format() method in the Java API as a good starting point.

// At some point you will need to call calculateGrade and calculateAverage. It would 
// be useful to do that before you output to screen. It can either be done in here or 
// in your main class before you call toString()
}
}

我认为你非常接近你需要的答案，你只需要将所有部分组合在一起。请以各种方式查看格式化字符串。

java成绩报告家庭作业

3 个答案: