Flyweight Design Pattern

10:41 Design patterns, Java Design Patterns, Structural Design Pattern No Comments

Some programs require to have a large number of objects that have some shared state among them. Consider for example a game of war, were there is a large number of soldier objects; a soldier object maintain the graphical representation of a soldier, soldier behavior such as motion, and firing weapons, in addition soldier’s health and location on the war terrain. Creating a large number of soldier objects is a necessity however it would incur a huge memory cost. Note that although the representation and behavior of a soldier is the same their health...

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What is Factory Design Patterns?

10:30 Creational Pattern, Design patterns, Java Design Patterns No Comments

Creational Patterns      -Factory Pattern Factory of classes. In simple words, if we have a super class and nth sub-classes, and based on data provided, we have to return the object of one of the sub-classes, we use a factory pattern. Let’s take an example to understand this pattern. Let’s suppose an application asks for entering the name and sex of a person. If the sex is Male (M), it displays welcome message saying Hello Mr. <Name> and if the sex is Female (F), it displays message  Welcome to application,  Ms...

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Functions Vs Stored Procedures

09:37 No Comments

It is one of the famous or frequently asked interview question, so I am stating the difference between these two which I think is appropriate, Please correct me if I have left anything unattended here. Basic difference is a procedure can return nth values whereas function can return only one value which is mandatory to be. Function can have only input parameters whereas procedures can have both input/output parameters. Function doesn't allow an update, delete, create(DML Statements) statements into it where as Procedure ...

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Nth PL/SQL to get Second largest Salary from table

09:00 PL/SQL No Comments

Today, I get an interview in which PL/SQL question was asked, we have a table lets say employee_master which has salary of employee, so requirement is to fetch the employee details who has second largest salary in table, This requirement can be implimented in various ways, Please find below the SQLs to achieve this: select top 1 Salary_amount from (select top 2 Salary_amount from employee_master order by salary_amount desc) a order by salary_amount asc ;with CTE AS( ...

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Types of IOC(Inversion of Control) or DI(Dependency Injection)

10:04 Spring 3.0 No Comments

There are two types of dependency injection: setter injection and constructor injection. Setter Injection: Normally in all the java beans, we will use setter and getter method to set and get the value of property as follows: public class namebean { String name;     public void setName(String a) {             name = a; }     public String getName() {     return name; }} We will create an instance of the bean 'namebean' (say bean1) and set property as bean1.setName("tom");...

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IOC(Inversion of control) Vs DI(Dependency injection)

10:00 Spring 3.0 No Comments

IOC and DI are one of the same thing in aspects of Spring Framework, Both are meant to be for same functionality. Dependency injection (DI) is a programming design pattern and architectural model, sometimes also referred to as inversion of control or IOC, although technically speaking, dependency injection specifically refers to an implementation of a particular form of IOC.  Dependency Injection describes the situation where one object uses a second object to provide a particular capacity. For example, being passed a database connection...

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What is Inversion Of Control(IOC)?

09:58 Spring 3.0 No Comments

Inversion of control or dependency injection (which is a specific type of IoC) is a term used to resolve objectdependencies by injecting an instantiated object to satisfy dependency as opposed to explicitly requesting anobject. So objects will not be explicitly requested but objects are provided as needed with the help of an Inversion Of Controller container (e.g. Spring etc).This is analogous to the Hollywood principal where the servicing objects say to the requesting client code (i.e. the caller) “don’t call us, we’ll call you”. Hence...

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