Java Sample - Copy any object into any object including sub object fields generic

 Steps 1:

Source

Person.java(list address)

Address.java(User.java)

public class Person implements Serializable

{

private String firstName;

private String lastName;

private int age;

private List <Address> addressList;

}

public class Address implements Serializable

{

private int id;

private String address1;

private String address2;

private String city;

private String state;

private String country;

private String pincode;

private String contactNumber;

private String email;

private User user;

}

Target

PersonDTO.java (list addressDTO)

AddressDTO.java (User.java)

public class PersonDTO implements Serializable

{

private String firstName;

private int age;

private String lastName;

private List <AddressDTO> addressList;

}

public class AddressDTO implements Serializable

{

private int id;

private String address1;

private String address2;

private String city;

private String state;

private String country;

private String pincode;

private String contactNumber;

private String email;

private User user;

}

Step 2: Sample java class

package com.drvijay;

import java.lang.reflect.Field;

import java.lang.reflect.Modifier;

import java.util.ArrayList;

import java.util.Arrays;

import java.util.HashMap;

import java.util.List;

import org.apache.commons.lang3.RandomStringUtils;

import com.product.base.utils.ObjectUtils;

import com.product.base.utils.ProductConstants;

/**

* @author drvijay

* @date Apr-20-2023 10:30 AM

*/

@SuppressWarnings ( "unused" )

public class UtilHelper

{

private static final long serialVersionUID = 1L;

public static void copy ( Object source, Object target ) throws IllegalArgumentException, IllegalAccessException

{

Class <?> sourceClass = source.getClass ();

Class <?> targetClass = target.getClass ();

Field [] sourceFields = sourceClass.getDeclaredFields ();

Field [] targetFields = targetClass.getDeclaredFields ();

for ( Field sourceField : sourceFields )

{

for ( Field targetField : targetFields )

{

// If the source and target fields have the same name and type

if ( sourceField.getName ().equals ( targetField.getName () ) && sourceField.getType ().equals ( targetField.getType () ) )

{

// Make the source and target field accessible

sourceField.setAccessible ( true );

targetField.setAccessible ( true );

// Copy the value from the source field to the target field

targetField.set ( target, sourceField.get ( source ) );

// Stop looping through the target fields

break;

}

}

}

}

public static void main ( String [] args ) throws Exception

{

// Create a source object

Person sourcePerson = new Person ();

sourcePerson.setFirstName ( "vijay" );

sourcePerson.setLastName ( "kumar" );

sourcePerson.setAge ( 30 );

User u = new User ();

u.setUA ( "ua" );

u.setUB ( "ub" );

List<Address> aList = new ArrayList();

Address address = new Address ();

address.setAddress1 ( "add 1" );

address.setAddress2 ( "add 2" );

address.setPincode ( "54534" );

address.setUser ( u );

aList.add ( address );

address = new Address ();

address.setAddress1 ( "add 11" );

address.setAddress2 ( "add 22" );

address.setPincode ( "545341" );

aList.add ( address );

sourcePerson.setAddressList ( aList );

// Create a target object with similar properties

PersonDTO targetPersonDTO = new PersonDTO ();

// Copy the properties from the source object to the target object

UtilHelper.copy ( sourcePerson, targetPersonDTO );

// Print the values of the target object

System.out.println ( targetPersonDTO.getFirstName () );

System.out.println ( targetPersonDTO.getAge () );

System.out.println ( sourcePerson.toString () );

System.out.println ( targetPersonDTO.toString () );

System.out.println ( targetPersonDTO.getAddressList ().toString () );

}

}

Output

vijay

30

Person(firstName=vijay, lastName=kumar, age=30, addressList=[Address(id=0, address1=add 1, address2=add 2, city=null, state=null, country=null, pincode=54534, contactNumber=null, email=null, user=User(uA=ua, uB=ub)), Address(id=0, address1=add 11, address2=add 22, city=null, state=null, country=null, pincode=545341, contactNumber=null, email=null, user=null)])

PersonDTO(firstName=vijay, age=30, lastName=kumar, addressList=[Address(id=0, address1=add 1, address2=add 2, city=null, state=null, country=null, pincode=54534, contactNumber=null, email=null, user=User(uA=ua, uB=ub)), Address(id=0, address1=add 11, address2=add 22, city=null, state=null, country=null, pincode=545341, contactNumber=null, email=null, user=null)])

[Address(id=0, address1=add 1, address2=add 2, city=null, state=null, country=null, pincode=54534, contactNumber=null, email=null, user=User(uA=ua, uB=ub)), Address(id=0, address1=add 11, address2=add 22, city=null, state=null, country=null, pincode=545341, contactNumber=null, email=null, user=null)]