如何使用 Student class 对象访问 Department class 的方法

Question

使用以下私有成员变量创建一个class部门

int did
String dname

在部门 class 中包含适当的 getter 和 setter 方法。

创建一个class具有以下私有成员变量的Student

int sid
String sname
Department department

在 Student class 中包含适当的 getter 和 setter 方法。

创建一个具有 main 方法的 TestMain class。

除了main方法，创建一个方法

       public static Student createStudent() -  All input as shown in the sample input should be got in this method.  Set the values to the Student object and return that object

注意：在 main 方法中，调用 createStudent 方法并打印该方法返回的对象的详细信息。

我已经尝试使用 Department 的名称创建一个新对象，但我无法访问这些方法

import java.util.Scanner;

public class TestMain {

    public static Student student;
    public static Department department;

    public static void main(String args[]) {
        createStudent();
        System.out.println("Department id:" + department.getDid());
        System.out.println("Department name:" + department.getDname());
        System.out.println("Student id:" + student.getSid());
        System.out.println("Student name:" + student.getSname());
    }

    public static Student createStudent() {
        Scanner sc = new Scanner(System.in);
        student = new Student();
        department = new Department();
        System.out.println("Enter the Department id:");
        department.setDid(sc.nextInt());
        System.out.println("Enter the Department name:");
        department.setDname(sc.next());
        System.out.println("Enter the Student id:");
        student.setSid(sc.nextInt());
        System.out.println("Enter the Student name:");
        student.setSname(sc.next());
        return student;
    }
}

public class Student {

    private int sid;
    private String sname;
    private Department department;

    public int getSid() {
        return sid;
    }

    public void setSid(int sid) {
        this.sid = sid;
    }

    public String getSname() {
        return sname;
    }

    public void setSname(String sname) {
        this.sname = sname;
    }

    public Department getDepartment() {
        return department;
    }

    public void setDepartment(Department department) {
        this.department = department;
    }
}

public class Department {

    private int did;
    private String dname;

    public int getDid() {
        return did;
    }

    public void setDid(int did) {
        this.did = did;
    }

    public String getDname() {
        return dname;
    }

    public void setDname(String dname) {
        this.dname = dname;
    }
}

示例输入 1：

Enter the Department id:
100
Enter the Department name:
Computerscience

Enter the Student id:
123
Enter the Student name:
Sudha

示例输出 1：

Department id:100
Department name:Computerscience
Student id:123
Student name:sudha

Answer 1

你还缺少：

student.setDepartment(department);

之后，您可以：

student.getDepartment().getSname();

Answer 2

import java.util.*;
public class TestMain
{
    public static Department d1;
    public static Student s1;
    public static Student createStudent()
    {
        Scanner sc=new Scanner(System.in);
        Student s1=new Student();
        Department d1=new Department();
        System.out.println("Enter the Department id:");
        int did=sc.nextInt();
        sc.nextLine();
        System.out.println("Enter the Department name:");
        String dname=sc.nextLine();
        System.out.println("Enter the Student id:");
        int sid=sc.nextInt();
        sc.nextLine();
        System.out.println("Enter the Student name:");
        String sname=sc.nextLine();
        d1.setDid(did);
        d1.setDname(dname);
        s1.setSid(sid);
        s1.setSname(sname);
        s1.setDepartment(d1);
        return s1;
    }
    public static void main(String[] args)
    {
        s1=TestMain.createStudent();
        System.out.println("Department id:"+d1.getDid());
        System.out.println("Department name:"+d1.getDname());
        System.out.println("Student id:"+s1.getSid());
        System.out.println("Student name:"+s1.getSname());
    }
}

Answer 3

public static void main(String args[]) throws NumberFormatException, IOException
{
 s1 =  createStudent();
 d1 = s1.getDepartment(); // THIS WAS MISSING IN ANSWER 2
 System.out.println("Department id:"+d1.getDid());
 System.out.println("Department name:"+d1.getDname());
 System.out.println("Student id:"+s1.getSid());
 System.out.println("Student name:"+s1.getSname());

}

Answer 4

在这种情况下，必须完成两件事。

在为所有 ID 和名称“设置”值时，在设置了 did 和 dname 之后，为了通过学生对象访问它，您必须“设置”did 和 dname 组合到 student class.
内部的 department 对象
```
department.setDid(did);
department.setDname(dname);
student.setSid(sid);
student.setSname(sname);
student.setDepartment(department);
```

此外，现在一旦设置了正确的值，在 Main 中的 Sysout 语句之前，您必须为部门 class 创建一个对象。并且此数据通过调用学生 class 中的 getDepartment() 来获取（请记住，此函数 returns 是部门对象）。

public static void main(String[] args) {
    // TODO Auto-generated method stub
    Student student = createStudent();
    Department department = student.getDepartment();
    System.out.printf("Department id:%d",department.getDid()).println();
    System.out.printf("Department name:%s",department.getDname()).println();
    System.out.printf("Student id:%d",student.getSid()).println();
    System.out.printf("Student name:%s",student.getSname()).println();
}

如何使用 Student class 对象访问 Department class 的方法

How can I access the methods of Department class using Student class object

java

class

object

getter-setter