Can we access private constructor in other package

How to access private constructor in other package:

Yes we can access by using reflection classes, we can create instance for private constructors.

To get the class.

Class c=Class.forName("test.Test");

To get all the constructors (public, protected, default, private) in the form of array from the class

Constructor con[]=c.getDeclaredConstructors();

con[0] is indicates first constructor, con[1] indicates second constructor and so an

if setAccessible(true) then all the constructors make as public

if setAccessible(false) then we can’t access all the constructors, we access only public constructors(depending on access specifier rules).

To create object for the class

con[0].newInstance(); 

Test.java

========

package test;

public class Test {

               private Test()

               {

                               System.out.println("private constructor...");                              

               }              

}

Client.java

=========

package core;

import java.lang.reflect.Constructor;

public class Client {

               public static void main(String[] arg)

               {

                               try{

                                              //to get the class

                                              Class c=Class.forName("test.Test");

                                              //to access all the constructors in the array form from the class

                                              Constructor con[]=c.getDeclaredConstructors();

                                              //to make constructor as public

                                              con[0].setAccessible(true);

                                              //to create object

                                              con[0].newInstance();

                               }catch(Exception ex){}

               }

}

/*

Output:

private constructor...

*/

First Spring application

Example of spring application

Creating first spring application in eclipse, here we have clear steps to create spring application

1. Create the java project

2. Add spring capabilities

3. Create the class file(POJO class)

4. Create the xml file

5. Create the Driver class

Download required jar files for first spring application

Create New Project:

Go to File menu - New - project - Java Project. Write the Project name and click Finish

Add Spring jar files:

Right click on project – Build Path – configure Build Path – select Libraries tab – Add External JARs

Create POJO class:

Test.java

=======

package test;

public class  Test

{

               public void hello()

               {

                               System.out.println("My first Spring Project");

               }

}

Create xml File:

Open org.springframework.beans-3.0.1.RELEASE-A.jar file with winJAR archiver

 and open folder org\springframework\beans\factory\xml

 in xml folder open spring-beans.dtd file

 in spring-beans.dtd file copy line 35 - 37 below code

 <!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN 2.0//EN"

"http://www.springframework.org/dtd/spring-beans-2.0.dtd">

spring.xml

========

package resources;

<!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN 2.0//EN"

"http://www.springframework.org/dtd/spring-beans-2.0.dtd">

<beans>

<bean class="test.Test" id="t">

</bean>

</beans>

Create Driver Class:

Client.java

========

package test;

class Client{

               public static void main(String[] args)

               {

                               //find xml file

                              Resource r=new ClassPathResource("resources/spring.xml");

                               //load xml file into container

                               BeanFactory factory=new XmlBeanFactory(r);

                               //creat test class object

                               Object o=factory.getBean("t");

                               //type casting object

                               Test t=(Test)o;

                               t.hello();

               }

}

/*

Output:

My first Spring Project

*/

Download first core Spring Application