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Singleton Pattern

 
Lakshmi siri
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Hi,
what is singleton pattern & Vaue Object Pattern?

Thanks
 
Venkatesh Chitnis
Greenhorn
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Hi Lakshmi,

I can answer your question about Singleton Design pattern.
A Singleton Design pattern is meant to instantiate a class only once. In many cases it is absolutely essential to have a unique instance of a class.

Here's one of the ways to implement the Singleton pattern:

class SingletonPattern
{
// Constructor
protected SingletonPattern()
{
// Add your code here
}

private static SingletonPattern instance = null;

public static SingletonPattern getInstance()
{
if (instance == null)
return new SingletonPattern();
else
return instance;
}

This design allows access to the getInstance method, but at the same time does not allow access to the SingletonPattern object.
 
Leandro Melo
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Value Object (VO) or Data Transfer Object (DTO) are patterns related on how your data should be transmitted among your application layers.
Bascially, put anything you need into a objetc, wich we'll call the transfer object.
See
http://java.sun.com/blueprints/corej2eepatterns/Patterns/TransferObject.html
 
Malli Raman
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Hi,

Value Object pattern is used to reduce the network traffic. Consider that you are requesting to get a customer detail from an Entity Bean Via a Session Bean. Instead of calling getCustomerName(), getCustomerAddress(), getCustomerCity() methods separately will increase the network traffic, Instead you can call getCustomerDetails() which inturn will return CustomerVO object which contains all the customer data.

Regards,
M.S.Raman
 
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