I am very new and learning java,I want to perform deep cloning without serialization ,I read some articles from internet and still in doubt about deep cloning without serialization.So i want to know is there any other rules that I have to follow to do deep cloning, below is my program
Department.java
package com.deepclone;
public class Department {
private int id;
private String name;
public Department(int id, String name) {
this.id = id;
this.name = name;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
Employee.java
package com.deepclone;
public class Employee implements Cloneable {
private String employeeId;
private String empName;
private Department department;
public Employee(String employeeId, String empName, Department department) {
this.employeeId = employeeId;
this.empName = empName;
this.department = department;
}
#Override
protected Object clone() throws CloneNotSupportedException {
Employee employee = new Employee(employeeId, empName, new Department(
department.getId(), department.getName()));
return employee;
}
public String getEmployeeId() {
return employeeId;
}
public void setEmployeeId(String employeeId) {
this.employeeId = employeeId;
}
public String getEmpName() {
return empName;
}
public void setEmpName(String empName) {
this.empName = empName;
}
public Department getDepartment() {
return department;
}
public void setDepartment(Department department) {
this.department = department;
}
}
TestCloning.java
package com.deepclone;
public class TestClonning1 {
public static void main(String[] args) throws CloneNotSupportedException {
Department hrDepartment = new Department(10, "HR");
Employee employee = new Employee("1", "rajeev", hrDepartment);
System.out.println(employee.getDepartment().getName());
Employee cloneEmployee = (Employee) employee.clone();
System.out.println(cloneEmployee.getDepartment().getName());
cloneEmployee.getDepartment().setName("it");
System.out.println(employee.getDepartment().getName());
System.out.println(cloneEmployee.getDepartment().getName());
}
}
output
HR
HR
HR
it
is there any other alternative to achive deep cloning without serialization...if yes then give link.
Try this Java Deep-Cloning Library
Cloner cloner = new Cloner();
MyClass other = ...;
MyClass clone = cloner.deepClone(other);
Related
I'm new to java reflexion and I'm trying to integrate SQLite with java.
I have 2 objects Person and Department. There is relation OneToMany between them.
As I'm working on save functionality (SQLite) I want to extract field names and its values so I can build full query. I have no problem with extracting names and values of fields that are of primitive type (String, int etc.). I have problem with type of Object (in this case it is Department field in Person object).
I'm able to print object but unable to access its fields (namely pk).
Could you help me please?
METHOD FOR EXTRACTING FIELDS
// method for extracting fields
private StringBuilder getFieldsWithValues(Object entity) throws IllegalAccessException, NoSuchFieldException {
StringBuilder query = new StringBuilder();
for (Field field : entity.getClass().getDeclaredFields()) {
System.out.print((field.getName() + " - "));
field.setAccessible(true);
// TODO: eliminate if statement from for cycle
if (field.isAnnotationPresent(ManyToOne.class)) {
// HERE I want to extract the pk value from Department object
System.out.println(field.get(entity));
} else {
System.out.println(field.get(entity));
}
}
return query;
}
DEPARTMENT OBJECT
import javax.persistence.Entity;
import javax.persistence.Id;
#Entity
public class Department {
#Id
private long pk;
private String name;
private String code;
public Department() {
}
public Department(String name, String code) {
this.name = name;
this.code = code;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getCode() {
return code;
}
public void setCode(String code) {
this.code = code;
}
public String toString() {
return String.format("Department %d: %s (%s)", pk, name, code);
}
}
PERSON OBJECT
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.ManyToOne;
#Entity
public class Person {
#Id
private long id;
private String surname;
private String name;
private int age;
#ManyToOne
private Department department;
public Person(String surname, String name, int age) {
this.surname = surname;
this.name = name;
this.age = age;
}
public Person() {
}
public String getSurname() {
return surname;
}
public void setSurname(String surname) {
this.surname = surname;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
public long getId() {
return id;
}
public Department getDepartment() {
return department;
}
public void setDepartment(Department department) {
this.department = department;
}
#Override
public String toString() {
return String.format("Person %d: %s %s (%d)", id, surname, name, age);
}
}
I have a class Named Employee which i am updating using the session.merge() method.
But this method is executing an insert statement and not an update statement.Please help!
#Autowired
private EntityManagerFactory entityManagerFactory;
public void updateEmployee() {
SessionFactory sessionFactory = entityManagerFactory.unwrap(SessionFactory.class);
Session session = sessionFactory.openSession();
Employee e = session.get(Employee.class, 3);
e.setName("changed!");
session.close();
Session session1 = sessionFactory.openSession();
Transaction transaction = session1.beginTransaction();
session1.merge(e);
transaction.commit();
session1.close();
}
Employee.class
#Entity
#Table(name = "Employee")
public class Employee implements Serializable {
public Employee(String name) {
super();
this.name = name;
}
public Employee() {
super();
}
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private int id;
private String name;
#OneToOne
#JoinColumn(name = "department")
private Department department;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Department getDepartment() {
return department;
}
public void setDepartment(Department department) {
this.department = department;
}
public Employee(String name, Department department) {
this.name = name;
this.department = department;
}
#Version
private Long version;
#Override
public String toString() {
return "Name :" + name + " Department" + department + "version:" + getVersion();
}
public Long getVersion() {
return version;
}
public void setVersion(Long version) {
this.version = version;
}
}
EmployeeController.java
#PutMapping(value = "/updateEmployee")
public void updateEmployee() {
dataServiceImpl.updateEmployee();
}
As i am just hitting this API a select query is being fired instead of an update query.Can anyone please explain me why is this happening.
The entire code is available here - https://github.com/iftekharkhan09/SpringAuthSecurity/tree/master/HibernateCaching
Any help is highly appreciated!
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I want to create bean in java corresponding to below json
{
"name": "",
"id": "",
"dept": {
"deptId": "",
"deptName": "",
"course": {
"courseId": "",
}
}
}
My idea is to create parent class and keep dept and course as inner private classes and then have getters setters to get or set data and form parent bean. But I am getting error "Change visibility to the public"
How can I access private fields of inner private class to get and set data?
try this way its will work
public class firstClass{
private String name;
private String id;
Department dept;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public Department getDept() {
return dept;
}
public void setDept(Department dept) {
this.dept = dept;
}
}
class Department{
private int departId;
private String deptName;
Course course;
public int getDepartId() {
return departId;
}
public void setDepartId(int departId) {
this.departId = departId;
}
public String getDeptName() {
return deptName;
}
public void setDeptName(String deptName) {
this.deptName = deptName;
}
public Course getCourse() {
return course;
}
public void setCourse(Course course) {
this.course = course;
}
}
class Course{
private int courseId;
public int getCourseId() {
return courseId;
}
public void setCourseId(int courseId) {
this.courseId = courseId;
}
}
You can't access private fields. Why don't you create a getter and setter for the inner class private fields?
And, maybe you should consider using gson library.
You at least have to make say nested public interfaces, say Dept and Course, with your private (static) nested private classes DeptImpl and SourceImpl.
public class X {
public interface Dept { ... }
private static class DeptImpl extends Dept { ... }
public Dept getDept() { ... }
public Dept createDept(...) {
DeptImpl dept = new DeptImpl(...); ...
return dept;
}
Maybe you need to provide a factory method createDept.
In some cases the implementing class can be anonymous new Dept() { ... }.
You can use Builder Design pattern with immutable Objects:
public class Class {
private final String name;
private final int id;
private final Department dept;
private Class(ClassBuilder classBuilder){
this.name = classBuilder.getName();
this.id = classBuilder.getId();
this.dept = classBuilder.getDept();
}
public String getName() {
return name;
}
public int getId() {
return id;
}
public Department getDept() {
return dept;
}
private static class Department{
private final int deptId;
private final String deptName;
private final Course course;
private Department(DepartmentBuilder departmentBuilder){
this.deptId = departmentBuilder.getDeptId();
this.deptName = departmentBuilder.getDeptName();
this.course = departmentBuilder.getCourse();
}
public int getDeptId() {
return deptId;
}
public String getDeptName() {
return deptName;
}
public Course getCourse() {
return course;
}
private static class Course{
private final int courseId;
private Course(CourseBuilder courseBuilder){
this.courseId = courseBuilder.getCourseId();
}
public int getCourseId() {
return courseId;
}
}
}
public static class ClassBuilder{
private final String name;
private final int id;
private final Department dept;
public ClassBuilder(String name, int id, Department dept){
this.name = name;
this.id = id;
this.dept = dept;
}
public Department getDept() {
return dept;
}
public String getName() {
return name;
}
public int getId() {
return id;
}
public Class build(){
return new Class(this);
}
}
public static class DepartmentBuilder {
private final int deptId;
private final String deptName;
private final Department.Course course;
public DepartmentBuilder(int deptId, String deptName, Department.Course course ){
this.deptId = deptId;
this.deptName = deptName;
this.course = course;
}
public int getDeptId() {
return deptId;
}
public String getDeptName() {
return deptName;
}
public Department.Course getCourse() {
return course;
}
public Department build(){
return new Department(this);
}
}
public static class CourseBuilder{
private final int courseId ;
public CourseBuilder(int courseId){
this.courseId = courseId;
}
public int getCourseId() {
return courseId;
}
public Department.Course build(){
return new Department.Course(this);
}
}
}
public class Sample {
public static void main(String ... strings){
Class clazz = new Class.ClassBuilder("ClassName", 1, new Class.DepartmentBuilder(1, "departmentName", new Class.CourseBuilder(2).build()).build()).build();
System.out.println(clazz.getDept());
}
}
Can someone help me i have those classes, and i want read out the getAllCustomer(), but i have no idea how i can implent it in my main method.
I tried already several things, but it didn't work well. Can anyone help me? :P
public static ArrayList<Customer> getAllCustomer() throws ClassNotFoundException, SQLException {
Connection conn=DBConnection.getDBConnection().getConnection();
Statement stm;
stm = conn.createStatement();
String sql = "Select * From Customer";
ResultSet rst;
rst = stm.executeQuery(sql);
ArrayList<Customer> customerList = new ArrayList<>();
while (rst.next()) {
Customer customer = new Customer(rst.getString("id"), rst.getString("name"), rst.getString("address"), rst.getDouble("salary"));
customerList.add(customer);
}
return customerList;
}
this is my model class
public class Customer {
private String id;
private String name;
private String salary;
private String address;
public Customer (String pId, String pName, String pSalary, String pAddress) {
id = pId;
name = pName;
salary = pSalary;
adress = pAddress;
}
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getSalary() {
return salary;
}
public void setSalary(String salary) {
this.salary = salary;
}
public String getAddress() {
return address;
}
public void setAddress(String address) {
this.address = address;
}
}
Assuming that your getAllCustomer() method is in class A . then in your main method, you do as follows
public void main(String[] args){
List<Customer> customers = A.getAllCustomer();
}
Based on the nature of your question, this JDBC tutorial will help you
The data type of your Salary field is String but you are getting the value as double.
All you need to do is to change the rst.getDouble("salary") to rst.getString("salary")
To call the method:
public static void main(String[] args)
ArrayList<Customer> customers = YourDALClass.getAllCustomer();
for(Customer c : customers){
System.out.println(c.getName());
}
}
I'm using XmlAdapter for immutable objects as proposed in this blog post: http://blog.bdoughan.com/2010/12/jaxb-and-immutable-objects.html. This works fine, but not with references to other immutable objects in my adapters. Is there any way to handle this with JAXB?
Below there is an example which does not work if the person's xml tag comes after the company's xml tag which references the person.
Immutable objects:
#XmlJavaTypeAdapter(PersonAdapter.class)
public class Person {
private final String id;
private final String name;
public Person(String id, String name) {
this.id = id;
this.name = name;
}
public String getId() {
return id;
}
public String getName() {
return name;
}
}
#XmlJavaTypeAdapter(CompanyAdapter.class)
public class Company {
private final String name;
private final Person principal;
public Company(String name, Person principal) {
this.name = name;
this.principal = principal;
}
public String getName() {
return name;
}
public Person getPrincipal() {
return principal;
}
}
PersonAdapter:
public class PersonAdapter extends XmlAdapter<AdaptedPerson, Person> {
public static class AdaptedPerson {
#XmlID
#XmlAttribute
String id;
#XmlAttribute
String name;
}
#Override
public AdaptedPerson marshal(Person v) throws Exception {
AdaptedPerson a = new AdaptedPerson();
a.id = v.getId();
a.name = v.getName();
return a;
}
#Override
public Person unmarshal(AdaptedPerson v) throws Exception {
return new Person(v.id, v.name);
}
}
CompanyAdapter:
public class CompanyAdapter extends XmlAdapter<AdaptedCompany, Company> {
public static class AdaptedCompany {
#XmlAttribute
String name;
#XmlIDREF
#XmlAttribute
Person principal;
}
#Override
public AdaptedCompany marshal(Company v) throws Exception {
AdaptedCompany a = new AdaptedCompany();
a.name = v.getName();
a.principal = v.getPrincipal();
return a;
}
#Override
public Company unmarshal(AdaptedCompany v) throws Exception {
return new Company(v.name, v.principal);
}
}