向学生班级添加多个考试成绩

Question

将教材第7章中的Student类修改如下： 每个学生对象还应包含三个不同测试的分数。在现有构造函数中将所有测试分数初始化为零。创建第二个构造函数（或重载构造函数）以根据参数参数值设置所有实例值。 提供此方法：

setTestScore：接受两个参数，测试编号（1 到 3）和分数。

getTestScore：接受测试号并返回相应的分数。

average：计算并返回学生的平均考试成绩。

toString: 考试成绩和平均成绩包含在学生的描述中。

之后修改驱动类的main方法来演示新的Student方法。

我卡在它（提示？）接受测试编号（1-3）的部分，然后根据该数字选择测试分数。但是，如果直接来自班级，我认为我不能输入任何整数。

package StudentBody;

public class StudentBody {
public static void main(String[] args) {

    Address school = new Address("800 Lancaster Ave.", "Villanova", "PA", 19085);
    Address jHome = new Address("21 Jump Street", "Blacksburg", "VA", 24551);

    Student john = new Student("John", "Smith", jHome, school);

    Address mHome = new Address("123 Main Street", "Euclid", "OH", 44132);
    Student marsha = new Student("Marsha", "Jones", mHome, school);

    System.out.println(john);
    System.out.println();
    System.out.println(marsha);

    }
}

public class Student {

private String firstName, lastName;
private Address homeAddress, schoolAddress;
private double score1, score2, score3;
private int testnumber;

public Student(String first, String last, Address home, Address school)
{
    firstName = first;
    lastName = last;
    homeAddress = home;
    schoolAddress = school;
    score1 = 0;
    score2 = 0;
    score3 = 0;
    testnumber = 0;
}
public Student(double score1_, double score2_, double score3_, int testnumber_)
{
    score1 = score1_;
    score2 = score2_;
    score3 = score3_;
    testnumber = testnumber_;
}
public void setTestScore(double score1_1, double score2_1, double score3_1, int testnumber1_1)
{
    score1 = score1_1;
    score2 = score2_1;
    score3 = score3_1;
    testnumber = testnumber1_1;
}
public double getTestScore()
{

}
public String toString()
{
    String result;

    result = firstName + " " + lastName + "\n";
    result += "Home Address:\n" + homeAddress + "\n";
    result += "School Address:" + schoolAddress;

    return result;
    }
}


public class Address {  
private String streetAddress, city, state;
private long zipCode;

public Address(String street, String town, String st, long zip)
{
    streetAddress = street;
    city = town;
    state = st;
    zipCode = zip;
}
public String toString()
{
    String result;

    result = streetAddress + "\n";
    result += city + ", " + state + " " + zipCode;

    return result;
}

}

Answer 1

我看到您已将分数和测试编号用作变量，即如下所示

private double score1, score2, score3;
private int testnumber;

相反，尝试将其作为 hashMap 。更改您的代码

    public void setTestScore(double score1_1, double score2_1, double score3_1, int testnumber1_1)
{
    score1 = score1_1;
    score2 = score2_1;
    score3 = score3_1;
    testnumber = testnumber1_1;
}

到下面的代码：

private HashMap<Integer, Integer> score;
    public void setTestScore( int testnumber,double score)
{
    score.put(testnumber,score);
}

另外，在初始构造函数中，将 hashMap 值设置为零。

    testMarks.put(1, 0);
    testMarks.put(2, 0);
    testMarks.put(3, 0);//1,2,3 are the test numbers

另外，这里不需要 2 个构造函数，因为重载的构造函数和 setTestScore 看起来一样。因此，使用初始构造函数并从代码中删除重载的构造函数。

Answer 2

我认为您的实现与您在第一个问题中的描述不正确。我修改了您的代码以了解如何执行此操作：
（更新为不使用数组）

public class StudentBody
{
    public static void main(String[] args) {
        Address school = new Address("800 Lancaster Ave.", "Villanova", "PA", 19085);
        Address jHome = new Address("21 Jump Street", "Blacksburg", "VA", 24551);
        Address mHome = new Address("123 Main Street", "Euclid", "OH", 44132);

        Student john = new Student("John", "Smith", jHome, school);
        Student marsha = new Student("Marsha", "Jones", mHome, school);

        Scanner in = new Scanner(System.in);
        int testNumber = in.nextInt(); // ask for test number

        System.out.println(john.getTestScore(testNumber));
        System.out.println(marsha.getTestScore(testNumber));

        // rest of your code
    }
}

class Student
{
    private String firstName, lastName;
    private Address homeAddress, schoolAddress;
    private double score1, score2, score3;

    public Student(String firstName, String lastName, Address homeAddress, Address schoolAddress) {
        this.firstName = firstName;
        this.lastName = lastName;
        this.homeAddress = homeAddress;
        this.schoolAddress = schoolAddress;
        // there is no need for score1 = score2 = score3 = 0; it is their default value
        // when object created.
    }

    public void setTestScore(int testNumber, double newScore) {
        if (testNumber < 1 || testNumber > 3) {
            // do something because test number is wrong
        }
        if (testNumber == 1)
            score1 = newScore;
        else if (testNumber == 2)
            score2 = newScore;
        else
            score3 = newScore;
    }

    public double getTestScore(int testNumber) {
        if (testNumber < 1 || testNumber > 3) {
            // do something because test number is wrong
        }
        if (testNumber == 1)
            return score1;
        else if (testNumber == 2)
            return score2;
        else
            return score3;
    }

    public double average() {
        return (score1 + score2 + score3) / 3;
    }

    public String toString() {
        return "Scores: " + score1 + " , " + score2 + " , " + score3 +
                " " + " average: " + average();
    }
}

class Address
{
    // same as you
}

很抱歉代码太多。我希望这是你想要的。