Question

我已将其作为任务的一部分：

private static void addStudent(int id, String firstName, String lastName,int 
mathsMark1, int mathsMark2, int mathsMark3, int englishMark1, int 
englishMark2, 
int englishMark3)

并附上说明：

创建一个新的Student对象和两个AsignmentMarks对象（用于数学和英语）。使用给定的参数分配这三个对象的值。请记住将两个AssignmentMarks对象分配给Student对象。最后，将学生添加到学生列表中。

学生班：

public class Student {

    private int id;
    private String firstName;
    private String lastName;
    public AssignmentMarks mathMarks;
    public AssignmentMarks englishMarks;

    public Student(int studentID, String firstName, String lastName, int 
    mathMark1, int mathMark2, int mathMark3, int englishMark1, int englishMark2, 
    int englishMark3) {

        id = studentID;
        this.firstName = firstName;
        this.lastName = lastName;

    }
}

分配标记类：

public class AssignmentMarks {

    private String courseName;
    private int assignment1;
    private int assignment2;
    private int assignment3;

    public AssignmentMarks(String name, int mark1, int mark2, int mark3) {

        courseName = name;
        assignment1 = mark1;
        assignment2 = mark2;
        assignment3 = mark3;        
    }
}

学生对象将添加到列表中。我的问题是“在我提供的说明中，没有人知道“记住将两个AssignmentMarks对象分配给Student对象”是什么意思吗？

我理解这个问题，而不是怎么做。

Answer 1

您必须创建两个AssignmentMarks实例：

一个englishMarks属性，
一个mathMarks属性。

对于英文商标：

this.englishMarks = new  AssignmentMarks("english", 
                         englishMark1, englishMark2, englishMark3);

您对mathMarks也做同样的事情。

Answer 2

似乎您想要或必须直接在此构造函数中处理提供给Student的构造函数的参数。您可以通过在其中创建新的AssignmentMarks并将其分配给Student的类属性来实现。没什么可做的，只需向Student类添加两行，如下所示：

public class Student {

    private int id;
    private String firstName;
    private String lastName;
    public AssignmentMarks mathMarks;
    public AssignmentMarks englishMarks;

    public Student(int studentID, String firstName, String lastName,
            int mathMark1, int mathMark2, int mathMark3,
            int englishMark1, int englishMark2, int englishMark3) {
        // assign the primitives and String attributes directly
        id = studentID;
        this.firstName = firstName;
        this.lastName = lastName;
        // assign the subject marks with newly created objects defined by parametrized constructor call
        mathMarks = new AssignmentMarks("maths", mathMark1, mathMark2, mathMark3);
        englishMarks = new AssignmentMarks("english", englishMark1, englishMark2, englishMark3);
    }
}

Answer 3

两个对象AssignmentMarks mathMarks和AssignmentMarks englishMarks在构造函数中未分配，因此使用null进行了初始化。但是，由于它们被声明为public，因此可以通过创建的对象进行分配。看起来像这样：

Student s = new Student(0, "Foo", "Bar", 1, 2, 3, 4, 5, 6);
//Note that the arguments int mathMark1, int mathMark2, 
//int mathMark3, int englishMark1, int englishMark2, int englishMark3 will be ignored

//s.mathMarks and s.englishMarks are null here
s.mathMarks = new AssignmentMarks("Math", 4, 5, 6);
//s.mathMarks is now initialized, s.englishMarks is not initialized.
s.englishMarks= new AssignmentMarks("English", 1, 2, 3);
//Both are initialized now.

希望对您有所帮助。

Answer 4

创建一个新的Student对象

Student student = new Student(id, firstName, lastName, mathsMark1, mathsMark2, mathsMark3, englishMark1, englishMark2, englishMark3);

和两个AsignmentMarks对象（用于数学和英语）

AssignmentMarks mathMarks = new AssignmentMarks("Mathematics", mathsMark1, mathsMark2, mathsMark3);
AssignmentMarks englishMarks = new AssignmentMarks("English", englishMark1, englishMark2, englishMark3);

记住要为学生分配两个AssignmentMarks对象对象。

student.mathMarks = mathMarks;
student.englishMarks = englishMarks;

最后，将“学生”添加到学生列表中。

// List<Student> students = new ArrayList<>();
students.add(student);

将对象分配给对象

4 个答案: