One-one

1.       One –to-One Association:

It is a relationship between entity classes, where one instance of an entity should be mapped with exactly one instance of another entity.

Ex :-

Every Employee HAS exactly one Account

Ex code:-

class Account

{

                String accNo;

                String accName;

                String accType;

                Account(String accNo, String accName, String accType)

                {

                                this.accNo=accNo;

                                this.accName=accName;

                                this.accType=accType;

                }

}

class Employee

{

                String eid;

                String ename;

                float esal;

                String eaddr;

                Account acc;

                Employee(String eid, String ename, float esal, String eaddr, Account acc)

                {

                                this.eid=eid;

                                this.ename=ename;

                                this.esal=esal;

                                this.eaddr=eaddr;

                                this.acc=acc;

                }

                public void getEmpDetails()

                {

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

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

                                System.out.println("Employee Id      :"+eid);

                                System.out.println("Employee Name    :"+ename);

                                System.out.println("Employee Salary  :"+esal);

                                System.out.println("Employee Address :"+eaddr);

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

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

                                System.out.println("Account Number   :"+acc.accNo);

                                System.out.println("Account Name     :"+acc.accName);

                                System.out.println("Account Type     :"+acc.accType);

                }

}

class OneToOneEx

{

                public static void main(String[] args)

                {

                                Account acc=new Account("abc123","Sai","Savings");

                                Employee emp=new Employee("E-111","Sai",50000.0f,"Hyd", acc);

                                emp.getEmpDetails();

                }

}

Output:-

Employee Details

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

Employee Id      :E-111

Employee Name    :Sai

Employee Salary  :50000.0

Employee Address :Hyd

Account Details

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

Account Number   :abc123

Account Name     :Sai

Account Type     :Saving

Flow of execution:-