Stream API in Java provides a powerful way to work with collections and other data sources. Mapping is one of the key operations available in the Stream API, used to transform elements of a stream. Here's a step-by-step guide on how to use the map function with the Stream API:
Import Required Classes :

Create a Stream:
You can create a stream from various sources, like collections, arrays, or generator functions. For example, creating a stream from a list:
Apply the map Function:
Use the map function to transform each element of the stream. For instance, to convert each name to uppercase:
Collect the Results:
Finally, you can collect the transformed stream back into a list or another collection:
Complete Example:
Here’s a complete example demonstrating how to use the map function with the Stream API:
import java.util.Arrays; import java.util.List; import java.util.stream.Collectors; public class StreamMapExample { public static void main(String[] args) { // Create a list of names List<String> names = Arrays.asList("a14mk", "manoj", "Jack"); // Convert the list to a stream List<String> upperCaseNames = names.stream() // Apply the map function to transform each name to uppercase .map(String::toUpperCase) // Collect the results back into a list .collect(Collectors.toList()); // Print the transformed list upperCaseNames.forEach(System.out::println); } }
Mapping with Complex Objects:
If you are working with a list of objects, you can use the map function to transform specific fields or create new objects. For example:
import java.util.Arrays; import java.util.List; import java.util.stream.Collectors; class Person { String name; int age; Person(String name, int age) { this.name = name; this.age = age; } public String getName() { return name; } public int getAge() { return age; } } public class StreamMapExample { public static void main(String[] args) { // Create a list of persons List<Person> people = Arrays.asList( new Person("a14mk", 25), new Person("manoj", 30), new Person("Jack", 35) ); // Transform the list to get a list of names List<String> names = people.stream().map(Person::getName).collect(Collectors.toList()); // Print the list of names names.forEach(System.out::println); } }
In this example, the map function is used to extract the names from a list of Person objects.

Many to Many Mapping : A many-to-many relationship refers to a relationship between tables in a database when a parent row in one table contains several child rows in the second table, and vice versa. Many-to-many relationships are often tricky to represent.

Many-to-Many mapping is usually implemented in database using a Join Table, for example we can have Cart, Item table and Cart_Items table for many-to-many mapping. Every cart can have multiple items and every item can be part of multiple carts, so we have a many to many mapping here.
1. Create Database Name is manytomany and Three Table are item, cart_items and cart.
CREATE TABLE `Cart` ( `cart_id` int( 11 ) unsigned NOT NULL AUTO_INCREMENT , `cart_total` decimal( 10, 0 ) NOT NULL , PRIMARY KEY ( `cart_id` ) ) CREATE TABLE `Item` ( `item_id` int( 11 ) unsigned NOT NULL AUTO_INCREMENT , `item_desc` varchar( 20 ) NOT NULL , `item_price` decimal( 10, 0 ) NOT NULL , PRIMARY KEY ( `item_id` ) ) CREATE TABLE `Cart_Items` ( `cart_id` int( 11 ) unsigned NOT NULL , `item_id` int( 11 ) unsigned NOT NULL , PRIMARY KEY ( `cart_id` , `item_id` ) , CONSTRAINT `fk_cart` FOREIGN KEY ( `cart_id` ) REFERENCES `Cart` ( `cart_id` ) , CONSTRAINT `fk_item` FOREIGN KEY ( `item_id` ) REFERENCES `Item` ( `item_id` ) )
Open NetBeans See The Menu Bar go to the file Menu Click on the New Project(Ctrl+Shift+N) and Select Left site categories Java/java web and Project categories to Right Site Project java/web Application .You have to give The Program Name "manytomany". if you wont to save Project Location you can Browse and File save on the direction place and Gone a default Place and Now uncheck/check the check box and click on the next button, select server settings and select the frameworks like Hibernate and go to the finish.
2. hibernate.cfg.xml
<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE hibernate-configuration PUBLIC "-//Hibernate/Hibernate Configuration DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd"> <hibernate-configuration> <session-factory> <property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property> <property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property> <property name="hibernate.connection.url">jdbc:mysql://localhost:3306/manytomany?zeroDateTimeBehavior=convertToNull</property> <property name="hibernate.connection.username">root</property> <property name="hibernate.show_sql">true</property> <mapping resource="manon/HBM/java/file/Cart.hbm.xml"/> <mapping resource="manon/HBM/java/file/CartItems.hbm.xml"/> <mapping resource="manon/HBM/java/file/Item.hbm.xml"/> </session-factory> </hibernate-configuration>
3. hibernate.reveng.xml
<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE hibernate-reverse-engineering PUBLIC "-//Hibernate/Hibernate Reverse Engineering DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-reverse-engineering-3.0.dtd"> <hibernate-reverse-engineering> <schema-selection match-catalog="manytomany"/> <table-filter match-name="cart"/> <table-filter match-name="cart_items"/> <table-filter match-name="item"/> </hibernate-reverse-engineering>
4. Item.java package manon.HBM.java.file; import java.util.Set; public class Item implements java.io.Serializable { private Integer itemId; private String itemDesc; private long itemPrice; private Set<cart> carts; public Item() { } public Set<cart> getCarts() { return carts; } public void setCarts(Set<cart> carts) { this.carts = carts; } public Item(String itemDesc, long itemPrice) { this.itemDesc = itemDesc; this.itemPrice = itemPrice; } public Integer getItemId() { return this.itemId; } public void setItemId(Integer itemId) { this.itemId = itemId; } public String getItemDesc() { return this.itemDesc; } public void setItemDesc(String itemDesc) { this.itemDesc = itemDesc; } public long getItemPrice() { return this.itemPrice; } public void setItemPrice(long itemPrice) { this.itemPrice = itemPrice; } }
5. CartItems.java
package manon.HBM.java.file; public class CartItems implements java.io.Serializable { private CartItemsId id; public CartItems() { } public CartItems(CartItemsId id) { this.id = id; } public CartItemsId getId() { return this.id; } public void setId(CartItemsId id) { this.id = id; } }
6. CartItemsId.java
package manon.HBM.java.file; public class CartItemsId implements java.io.Serializable { private int cartId; private int itemId; public CartItemsId() { } public CartItemsId(int cartId, int itemId) { this.cartId = cartId; this.itemId = itemId; } public int getCartId() { return this.cartId; } public void setCartId(int cartId) { this.cartId = cartId; } public int getItemId() { return this.itemId; } public void setItemId(int itemId) { this.itemId = itemId; } public boolean equals(Object other) { if ( (this == other ) ) return true; if ( (other == null ) ) return false; if ( !(other instanceof CartItemsId) ) return false; CartItemsId castOther = ( CartItemsId ) other; return (this.getCartId()==castOther.getCartId()) && (this.getItemId()==castOther.getItemId()); } public int hashCode() { int result = 17; result = 37 * result + this.getCartId(); result = 37 * result + this.getItemId(); return result; } }
7. Cart.java
package manon.HBM.java.file; import java.util.Set; public class Cart implements java.io.Serializable { private Integer cartId; private long cartTotal; private Set<item> items; public Cart() { } public Set<item> getItems() { return items; } public void setItems(Set<item> items) { this.items = items; } public Cart(long cartTotal) { this.cartTotal = cartTotal; } public Integer getCartId() { return this.cartId; } public void setCartId(Integer cartId) { this.cartId = cartId; } public long getCartTotal() { return this.cartTotal; } public void setCartTotal(long cartTotal) { this.cartTotal = cartTotal; } }
8. Item.hbm.xml
<?xml version="1.0"?> <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd"> <!-- Generated May 29, 2016 10:33:38 AM by Hibernate Tools 4.3.1 --> <hibernate-mapping> <class name="manon.HBM.java.file.Item" table="item" catalog="manytomany" optimistic-lock="version"> <id name="itemId" type="java.lang.Integer"> <column name="item_id" /> <generator class="identity" /> </id> <property name="itemDesc" type="string"> <column name="item_desc" length="20" not-null="true" /> </property> <property name="itemPrice" type="long"> <column name="item_price" precision="10" scale="0" not-null="true" /> </property> <set name="carts" table="cart_items" fetch="select" cascade="all"> <key column="item_id" /> <many-to-many class="manon.HBM.java.file.Cart" column="cart_id" /> </set> </class> </hibernate-mapping>
9. CartItems.hbm.xml
<?xml version="1.0"?> <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd"> <!-- Generated May 29, 2016 10:33:38 AM by Hibernate Tools 4.3.1 --> <hibernate-mapping> <class name="manon.HBM.java.file.CartItems" table="cart_items" catalog="manytomany" optimistic-lock="version"> <composite-id name="id" class="manon.HBM.java.file.CartItemsId"> <key-property name="cartId" type="int"> <column name="cart_id" /> </key-property> <key-property name="itemId" type="int"> <column name="item_id" /> </key-property> </composite-id> </class> </hibernate-mapping>
10. Cart.hbm.xml
<?xml version="1.0"?> <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd"> <!-- Generated May 29, 2016 10:33:38 AM by Hibernate Tools 4.3.1 --> <hibernate-mapping> <class name="manon.HBM.java.file.Cart" table="cart" catalog="manytomany" optimistic-lock="version"> <id name="cartId" type="java.lang.Integer"> <column name="cart_id" /> <generator class="identity" /> </id> <property name="cartTotal" type="long"> <column name="cart_total" precision="10" scale="0" not-null="true" /> </property> <set name="items" table="cart_items" fetch="select" cascade="all"> <key column="cart_id" /> <many-to-many class="manon.HBM.java.file.Item" column="item_id" /> </set> </class> </hibernate-mapping>
11. ManyToMany.java
package manoj.main.file; import java.util.HashSet; import java.util.Set; import manon.HBM.java.file.Cart; import manon.HBM.java.file.Item; import org.hibernate.Session; import org.hibernate.SessionFactory; import org.hibernate.cfg.Configuration; public class ManyToMany { public static void main(String[] args) { Item iphone = new Item(); iphone.setItemPrice(100); iphone.setItemDesc("iPhone5s"); Item ipod = new Item(); ipod.setItemPrice(50); ipod.setItemDesc("iPod5s"); Set<item> items = new HashSet<item>(); items.add(iphone); items.add(ipod); Cart cart = new Cart(); cart.setItems(items); cart.setCartTotal(50); Cart cart1 = new Cart(); Set<item> items1 = new HashSet<item>(); items1.add(iphone); items1.add(ipod); cart1.setItems(items1); cart1.setCartTotal(100); SessionFactory sessionFactory = null; try{ Configuration cf=new Configuration(); cf.configure("hibernate.cfg.xml"); SessionFactory factory = cf.buildSessionFactory(); Session session1=factory.openSession(); session1.getTransaction().begin(); session1.save(cart); session1.save(cart1); System.out.println("Before committing transaction"); session1.getTransaction().commit(); session1.close(); System.out.println("Cart ID="+cart.getCartId()); System.out.println("Cart1 ID="+cart1.getCartId()); System.out.println("Item1 ID="+iphone.getItemId()); System.out.println("Item2 ID="+ipod.getItemId()); }catch(Exception e){ e.printStackTrace(); } } }
OUTPUT:
Hibernate: insert into manytomany.cart (cart_total) values (?) Hibernate: insert into manytomany.item (item_desc, item_price) values (?, ?) Hibernate: insert into manytomany.item (item_desc, item_price) values (?, ?) Hibernate: insert into manytomany.cart (cart_total) values (?) Before committing transaction Hibernate: insert into cart_items (cart_id, item_id) values (?, ?) Hibernate: insert into cart_items (cart_id, item_id) values (?, ?) Hibernate: insert into cart_items (cart_id, item_id) values (?, ?) Hibernate: insert into cart_items (cart_id, item_id) values (?, ?) Cart ID=7 Cart1 ID=8 Item1 ID=5 Item2 ID=6

One to Many Mapping: A single attribute of a table relating with multiple attributes of another table is referred as One to Many mapping. A department may have multiple employees.

1. Create Database Name is mapping and Two Table are employee1 and department.
CREATE TABLE `department` ( `department_id` BIGINT(20) NOT NULL AUTO_INCREMENT, `dept_name` VARCHAR(50) NOT NULL DEFAULT '0', PRIMARY KEY (`department_id`) ) COLLATE='latin1_swedish_ci' ENGINE=InnoDB ROW_FORMAT=DEFAULT AUTO_INCREMENT=115 CREATE TABLE `employee` ( `employee_id` BIGINT(10) NOT NULL AUTO_INCREMENT, `firstname` VARCHAR(50) NULL DEFAULT NULL, `lastname` VARCHAR(50) NULL DEFAULT NULL, `birth_date` DATE NULL DEFAULT NULL, `cell_phone` VARCHAR(15) NULL DEFAULT NULL, `department_id` BIGINT(20) NULL DEFAULT NULL, PRIMARY KEY (`employee_id`), INDEX `FK_DEPT` (`department_id`), CONSTRAINT `FK_DEPT` FOREIGN KEY (`department_id`) REFERENCES `department` (`department_id`) ) COLLATE='latin1_swedish_ci' ENGINE=InnoDB ROW_FORMAT=DEFAULT
Open NetBeans See The Menu Bar go to the file Menu Click on the New Project(Ctrl+Shift+N) and Select Left site categories java web and Project categories to Right Site Project web Application .You have to give The Program Name "OnetoManyMapping". if you wont to save Project Location you can Browse and File save on the direction place and Gone a default Place and Now uncheck/check the check box and click on the next button, select server settings and select the frameworks like Hibernate and go to the finish.
2. hibernate.cfg.xml
<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE hibernate-configuration PUBLIC "-//Hibernate/Hibernate Configuration DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd"> <hibernate-configuration> <session-factory> <property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property> <property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property> <property name="hibernate.connection.url">jdbc:mysql://localhost:3306/mapping?zeroDateTimeBehavior=convertToNull</property> <property name="hibernate.connection.username">root</property> <property name="hibernate.show_sql">true</property> <mapping resource="onetomany/manoj/Employee1.hbm.xml"/> <mapping resource="onetomany/manoj/Department.hbm.xml"/> </session-factory> </hibernate-configuration>
3. hibernate.reveng.xml
<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE hibernate-reverse-engineering PUBLIC "-//Hibernate/Hibernate Reverse Engineering DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-reverse-engineering-3.0.dtd"> <hibernate-reverse-engineering> <schema-selection match-catalog="mapping"/> <table-filter match-name="employee1"/> <table-filter match-name="department"/> </hibernate-reverse-engineering>
4. Employee1.java
package onetomany.manoj; import java.util.Date; public class Employee1 implements java.io.Serializable { private Long employeeId; private Department department; private String firstname; private String lastname; private Date birthDate; private String cellPhone; public Employee1() { } public Employee1(Department department, String firstname, String lastname, Date birthDate, String cellPhone) { this.department = department; this.firstname = firstname; this.lastname = lastname; this.birthDate = birthDate; this.cellPhone = cellPhone; } public Long getEmployeeId() { return this.employeeId; } public void setEmployeeId(Long employeeId) { this.employeeId = employeeId; } public Department getDepartment() { return this.department; } public void setDepartment(Department department) { this.department = department; } public String getFirstname() { return this.firstname; } public void setFirstname(String firstname) { this.firstname = firstname; } public String getLastname() { return this.lastname; } public void setLastname(String lastname) { this.lastname = lastname; } public Date getBirthDate() { return this.birthDate; } public void setBirthDate(Date birthDate) { this.birthDate = birthDate; } public String getCellPhone() { return this.cellPhone; } public void setCellPhone(String cellPhone) { this.cellPhone = cellPhone; } }
5. Department.java
package onetomany.manoj; import java.util.HashSet; import java.util.Set; public class Department implements java.io.Serializable { private Long departmentId; private String deptName; private Set<employee1> employee1s = new HashSet<employee1>(0); public Department() { } public Department(String deptName) { this.deptName = deptName; } public Department(String deptName, Set<employee1> employee1s) { this.deptName = deptName; this.employee1s = employee1s; } public Long getDepartmentId() { return this.departmentId; } public void setDepartmentId(Long departmentId) { this.departmentId = departmentId; } public String getDeptName() { return this.deptName; } public void setDeptName(String deptName) { this.deptName = deptName; } public Set<employee1> getEmployee1s() { return this.employee1s; } public void setEmployee1s(Set<employee1> employee1s) { this.employee1s = employee1s; } }
6. Employee1.hbm.xml
<?xml version="1.0"?> <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd"> <!-- Generated May 15, 2016 11:55:12 AM by Hibernate Tools 4.3.1 --> <hibernate-mapping> <class name="onetomany.manoj.Employee1" table="employee1" catalog="mapping" optimistic-lock="version"> <id name="employeeId" type="java.lang.Long"> <column name="employee_id" /> <generator class="identity" /> </id> <many-to-one name="department" class="onetomany.manoj.Department" fetch="select"> <column name="department_id" /> </many-to-one> <property name="firstname" type="string"> <column name="firstname" length="50" /> </property> <property name="lastname" type="string"> <column name="lastname" length="50" /> </property> <property name="birthDate" type="date"> <column name="birth_date" length="10" /> </property> <property name="cellPhone" type="string"> <column name="cell_phone" length="15" /> </property> </class> </hibernate-mapping>
7. Department.hbm.xml
<?xml version="1.0"?> <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd"> <!-- Generated May 15, 2016 11:55:12 AM by Hibernate Tools 4.3.1 --> <hibernate-mapping> <class name="onetomany.manoj.Department" table="department" catalog="mapping" optimistic-lock="version"> <id name="departmentId" type="java.lang.Long"> <column name="department_id" /> <generator class="identity" /> </id> <property name="deptName" type="string"> <column name="dept_name" length="50" not-null="true" /> </property> <set name="employee1s" table="employee1" inverse="true" lazy="true" fetch="select"> <key> <column name="department_id" /> </key> <one-to-many class="onetomany.manoj.Employee1" /> </set> </class> </hibernate-mapping>
8. OnetoMany.java
package main.com; import java.util.Date; import onetomany.manoj.Department; import org.hibernate.Session; import org.hibernate.SessionFactory; import org.hibernate.cfg.Configuration; import onetomany.manoj.Employee1; /** * * @author manojkumar */ public class OnetoMany { public static void main(String[] args) { Configuration cf=new Configuration(); cf.configure("hibernate.cfg.xml"); SessionFactory factory = cf.buildSessionFactory(); Session session1=factory.openSession(); session1.getTransaction().begin(); Department department = new Department(); department.setDeptName("SoftwareS"); Employee1 emp1 = new Employee1(department,"manoj", "kumar", new Date(), "81200638"); session1.save(department); session1.save(emp1); session1.getTransaction().commit(); session1.close(); } }
OUTPUT: Hibernate: insert into mapping.department (dept_name) values (?) Hibernate: insert into mapping.employee1 (department_id, firstname, lastname, birth_date, cell_phone) values (?, ?, ?, ?, ?)

A one-to-one relationships occurs when one entity is related to exactly one occurrence in another entity. Thus, there will be one primary key which will be mapped with both the entities.
1. Create Database Name is mapping and Two Table are employee and employeedetail.
/* EMPLOYEE table */ CREATE TABLE `employee` ( `employee_id` BIGINT(10) NOT NULL AUTO_INCREMENT, `firstname` VARCHAR(50) NULL DEFAULT NULL, `lastname` VARCHAR(50) NULL DEFAULT NULL, `birth_date` DATE NOT NULL, `cell_phone` VARCHAR(15) NOT NULL, PRIMARY KEY (`employee_id`) ) COLLATE='latin1_swedish_ci' ENGINE=InnoDB ROW_FORMAT=DEFAULT AUTO_INCREMENT=216 /* EMPLOYEEDETAIL table */ CREATE TABLE `employeedetail` ( `employee_id` BIGINT(20) NOT NULL AUTO_INCREMENT, `street` VARCHAR(50) NULL DEFAULT NULL, `city` VARCHAR(50) NULL DEFAULT NULL, `state` VARCHAR(50) NULL DEFAULT NULL, `country` VARCHAR(50) NULL DEFAULT NULL, PRIMARY KEY (`employee_id`), CONSTRAINT `FKEMPL` FOREIGN KEY (`employee_id`) REFERENCES `employee` (`employee_id`) ) COLLATE='latin1_swedish_ci' ENGINE=InnoDB ROW_FORMAT=DEFAULT AUTO_INCREMENT=216
Open NetBeans See The Menu Bar go to the file Menu Click on the New Project(Ctrl+Shift+N) and Select Left site categories java web and Project categories to Right Site Project web Application .You have to give The Program Name "Mapping". if you wont to save Project Location you can Browse and File save on the direction place and Gone a default Place and Now uncheck/check the check box and click on the next button, select server settings and select the frameworks like Hibernate and go to the finish.

2. hibernate.cfg.xml
<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE hibernate-configuration PUBLIC "-//Hibernate/Hibernate Configuration DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd"> <hibernate-configuration> <session-factory> <property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property> <property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property> <property name="hibernate.connection.url">jdbc:mysql://localhost:3306/mapping?zeroDateTimeBehavior=convertToNull</property> <property name="hibernate.connection.username">root</property> <mapping resource="com/manoj/kumar/net/Employeedetail.hbm.xml"/> <mapping resource="com/manoj/kumar/net/Employee.hbm.xml"/> </session-factory> </hibernate-configuration>
3. hibernate.reveng.xml
<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE hibernate-reverse-engineering PUBLIC "-//Hibernate/Hibernate Reverse Engineering DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-reverse-engineering-3.0.dtd"> <hibernate-reverse-engineering> <schema-selection match-catalog="mapping"/> <table-filter match-name="employeedetail"/> <table-filter match-name="employee"/> </hibernate-reverse-engineering>
4. Employee.java
package com.manoj.kumar.net; import java.util.Date; /** * Employee generated by hbm2java */ public class Employee implements java.io.Serializable { private Long employeeId; private String firstname; private String lastname; private Date birthDate; private String cellPhone; private Employeedetail employeedetail; private ID id; public Employee(ID id) { this.id = id; } public ID getId() { return id; } public void setId(ID id) { this.id = id; } public Employee() { } public Employee(String firstname, String lastname, Date birthDate, String cellPhone) { this.firstname = firstname; this.lastname = lastname; this.birthDate = birthDate; this.cellPhone = cellPhone; } public Employee(Date birthDate, String cellPhone) { this.birthDate = birthDate; this.cellPhone = cellPhone; } public Employee(String firstname, String lastname, Date birthDate, String cellPhone, Employeedetail employeedetail) { this.firstname = firstname; this.lastname = lastname; this.birthDate = birthDate; this.cellPhone = cellPhone; this.employeedetail = employeedetail; } public Long getEmployeeId() { return this.employeeId; } public void setEmployeeId(Long employeeId) { this.employeeId = employeeId; } public String getFirstname() { return this.firstname; } public void setFirstname(String firstname) { this.firstname = firstname; } public String getLastname() { return this.lastname; } public void setLastname(String lastname) { this.lastname = lastname; } public Date getBirthDate() { return this.birthDate; } public void setBirthDate(Date birthDate) { this.birthDate = birthDate; } public String getCellPhone() { return this.cellPhone; } public void setCellPhone(String cellPhone) { this.cellPhone = cellPhone; } public Employeedetail getEmployeedetail() { return this.employeedetail; } public void setEmployeedetail(Employeedetail employeedetail) { this.employeedetail = employeedetail; } }
5. Employeedetail.java
package com.manoj.kumar.net; public class Employeedetail implements java.io.Serializable { private Long employeeId; private Employee employee; private String street; private String city; private String state; private String country; public Employeedetail() { } public Employeedetail(String street, String city, String state, String country) { this.street = street; this.city = city; this.state = state; this.country = country; } public Employeedetail(Employee employee) { this.employee = employee; } public Employeedetail(Employee employee, String street, String city, String state, String country) { this.employee = employee; this.street = street; this.city = city; this.state = state; this.country = country; } public Long getEmployeeId() { return this.employeeId; } public void setEmployeeId(Long employeeId) { this.employeeId = employeeId; } public Employee getEmployee() { return this.employee; } public void setEmployee(Employee employee) { this.employee = employee; } public String getStreet() { return this.street; } public void setStreet(String street) { this.street = street; } public String getCity() { return this.city; } public void setCity(String city) { this.city = city; } public String getState() { return this.state; } public void setState(String state) { this.state = state; } public String getCountry() { return this.country; } public void setCountry(String country) { this.country = country; } }
6. Employee.hbm.xml
<?xml version="1.0"?> <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd"> <!-- Generated Apr 14, 2016 4:15:02 PM by Hibernate Tools 4.3.1 --> <hibernate-mapping> <class name="com.manoj.kumar.net.Employee" table="employee" catalog="mapping" optimistic-lock="version"> <id name="employeeId" type="java.lang.Long"> <column name="employee_id" /> <generator class="identity" > </generator> </id> <property name="firstname" type="string"> <column name="firstname" length="50" /> </property> <property name="lastname" type="string"> <column name="lastname" length="50" /> </property> <property name="birthDate" type="date"> <column name="birth_date" length="10" not-null="true" /> </property> <property name="cellPhone" type="string"> <column name="cell_phone" length="15" not-null="true" /> </property> <one-to-one name="employeedetail" class="com.manoj.kumar.net.Employeedetail"></one-to-one> <one-to-one name="id" class="com.manoj.kumar.net.ID"></one-to-one> </class> </hibernate-mapping>
7. Employeedetail.hbm.xml
<?xml version="1.0"?> <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd"> <!-- Generated Apr 14, 2016 4:15:02 PM by Hibernate Tools 4.3.1 --> <hibernate-mapping> <class name="com.manoj.kumar.net.Employeedetail" table="employeedetail" catalog="mapping" optimistic-lock="version"> <id name="employeeId" type="java.lang.Long"> <column name="employee_id" /> <generator class="foreign"> <param name="property">employee</param> </generator> </id> <one-to-one name="employee" class="com.manoj.kumar.net.Employee" constrained="true"></one-to-one> <property name="street" type="string"> <column name="street" length="50" /> </property> <property name="city" type="string"> <column name="city" length="50" /> </property> <property name="state" type="string"> <column name="state" length="50" /> </property> <property name="country" type="string"> <column name="country" length="50" /> </property> </class> </hibernate-mapping>
8. OnetoOnemapping.java
package manoj.mapping.file; import java.util.Date; import java.util.List; import com.manoj.kumar.net.Employee; import com.manoj.kumar.net.Employeedetail; import org.hibernate.Session; import org.hibernate.SessionFactory; import org.hibernate.cfg.Configuration; import com.manoj.kumar.net.ID; /** * * @author manojkumar */ public class OnetoOnemapping { public static void main(String[] args) { Configuration cf=new Configuration(); cf.configure("hibernate.cfg.xml"); SessionFactory factory = cf.buildSessionFactory(); Session session1=factory.openSession(); session1.getTransaction().begin(); ID id1=new ID(); Employeedetail employeeDetail = new Employeedetail("15th Street", "New Delhi", "Delhi", "India"); Employee employee = new Employee("manoj", "kumar", new Date(), "114-857-965"); employee.setEmployeedetail(employeeDetail); employeeDetail.setEmployee(employee); id1.setEmp(employee); session1.save(employee); session1.save(employeeDetail); session1.save(id1); List<employee> employees = session1.createQuery("From Employee").list(); for (Employee employee1 : employees) { System.out.println(employee1.getFirstname() + " , " + employee1.getLastname() + ", " + employee1.getEmployeedetail()); } session1.getTransaction().commit(); session1.close(); } } 9. output- 
Hibernate: insert into mapping.employee (firstname, lastname, birth_date, cell_phone) values (?, ?, ?, ?) Hibernate: insert into mapping.employeedetail (street, city, state, country, employee_id) values (?, ?, ?, ?, ?) Hibernate: insert into mapping.id (employee_id) values (?)