Many-one

1.       Many-To-One Association:

It is relation between entities, where, multiple instance of an entity must be mapped with exactly one instance of another entity.

Ex:-

Multiple student, have joined with single Branch.

Ex code :-

class Branch

{

                String bid;

                String bname;

                Branch(String bid, String bname)

                {

                                this.bid=bid;

                                this.bname=bname;

                }

}

class Student

{

                String sid;

                String sname;

                String saddr;

                Branch branch;

    Student(String sid, String sname, String saddr, Branch branch)

    {

                this.sid=sid;

                this.sname=sname;

                this.saddr=saddr;

                this.branch=branch;

    }

    public void getStudentDetails()

    {

                System.out.println("Student Details");

                System.out.println("---------------");

                System.out.println("Student Id     :"+sid);

                System.out.println("Student Name   :"+sname);

                System.out.println("Student Address:"+saddr);

                System.out.println("Branch Id    :"+branch.bid);

                System.out.println("Branch Name  :"+branch.bname);

                System.out.println();

    }

}

class ManyToOneEx

{

                public static void main(String[] args)

                {

                                Branch branch=new Branch("B-111","CS");

                                Student std1=new Student("S-111","AAA","Hyd",branch);

                                Student std2=new Student("S-222","BBB","Hyd",branch);

                                Student std3=new Student("S-333","CCC","Hyd",branch);

                               

                                std1.getStudentDetails();

                                std2.getStudentDetails();

                                std3.getStudentDetails();

                               

                }

}

Output:-

Student Details

---------------

Student Id     :S-111

Student Name   :AAA

Student Address:Hyd

Branch Id    :B-111

Branch Name  :CS

Student Details

---------------

Student Id     :S-222

Student Name   :BBB

Student Address:Hyd

Branch Id    :B-111

Branch Name  :CS

Student Details

---------------

Student Id     :S-333

Student Name   :CCC

Student Address:Hyd

Branch Id    :B-111

Branch Name  :CS