Singleton Design pattern in JAVA


Below class depicts the Singleton design pattern.

SingletonDesignPattern.java

package in.javatutorials;

/**
* @author JavaTutorials
* @version 1.0
*
*/
public final class SingletonDesignPattern {

/**
* make the class object as private as it is
* not used directly out side the class
*/
private static SingletonDesignPattern singletonObj = null;

/**
* make the constructor as private.
* Object cannot be created using the constructor outside of this class.
*/
private SingletonDesignPattern(){

}

/**
* Create the class object if it is null and
*
* @return singletonObj SingletonDesignPattern
*/
public static SingletonDesignPattern getInstance(){
if(singletonObj == null){
singletonObj = new SingletonDesignPattern();
}
return singletonObj;
}

/**
* Take the user name as parameter and return the welcome message
*
* @param userName String
* @return message String
*/
public String getWelcomeInfo(String userName){
String message = null;
//make method access to synchronized to make thread safe
synchronized (SingletonDesignPattern.class) {
System.out.println(“User Name is : ” + userName);
message = “Hello ” + userName + “!!!”;
}
return message;
}
}

 

TestSingleton.java

The main() method of below class will get the single ton object and access the other methods using the same.

package in.javatutorials;

public class TestSingleton {

public static void main(String[] args) {
//Get the singleton object
SingletonDesignPattern singletonObj = SingletonDesignPattern.getInstance();

System.out.println(singletonObj.getWelcomeInfo(“Mallik”));
}

}

4 thoughts on “Singleton Design pattern in JAVA

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.