Mitchel  Carter

Mitchel Carter

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Singleton Design Pattern

Design patterns help us make code maintainable, extensible, and loosely coupled. One such design pattern is the Singleton Design pattern.

Design patterns are important as they help us solve general problems with software that people face during development. These patterns help us make code maintainable, extensible, and loosely coupled. One such design pattern is the Singleton Design pattern.

In simple terms, Singleton is a class that allows us only to create a single instance of it. It makes it impossible for us to instantiate the class for the second time.

There are different Singleton design implementations available like eager Initialization, lazy Initialization, Thread-safe singleton, and many more. Here we will go through the basic lazy Initialization Singleton.

Implementing the Singleton Pattern

The first step towards making a Class Singleton is to define the class constructor as private. This means nobody from outside cannot construct that class. The private constructor will not allow us to create an instance outside the class.

Note: But here is one interesting point about this, only singletons can instantiate singletons.

But this leads to another question. How do we create the Singleton object the first time? And if somehow we are able to create it how do we access it? This problem is solved by creating a static method of the Singleton class which returns a static Singleton object.

#java #design-pattern

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Singleton Design Pattern
Seamus  Quitzon

Seamus Quitzon

1601479980

Confused With Java Singleton Design Pattern? Have a Look at This Article.

What Is a Singleton Design Pattern?

  1. Singleton design pattern allows us to create only one instance of a class and make sure that there exists only one Object in JVM.
  2. Singleton class must have a public static method to get the instance of the class from anywhere in the application [from different classes, different packages, etc].
  3. Singleton class must have a private constructor to instantiate the object of the class.
  4. Singleton class must have a private static variable of the same class which is the only reference of the class[basically this variable will point to only Object of class].

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Singleton Design Pattern

All these different implementation methods lead to one goal that is having a single instance of a class at any given point of time in JVM. Let’s see different implementation approaches for the Singleton design pattern


1. Eager Initialization :

  1. This is the simplest implementation of the singleton design pattern class. In this method, the private static variable of the same class [reference] is assigned the object of class at the time of loading the class into the JVM memory.
  2. This type of implementation is applicable to the scenarios when we always want the instance of the class.

Let’s see the program to understand this …

package com.vikram;

	public class EagerSingleton {
	    //Only object created when class is loaded and theInstance is private static var pointing to it.
	    private static EagerSingleton theInstance = new EagerSingleton();

	    //private constructor
	    private EagerSingleton(){

	    }
	    //public method to return single instance of class .
	    public static EagerSingleton getInstance(){
	        return theInstance;
	    }
	}

Eager Initialization

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Samanta  Moore

Samanta Moore

1623835440

Builder Design Pattern

What is Builder Design Pattern ? Why we should care about it ?

Starting from **Creational Design Pattern, **so wikipedia says “creational design pattern are design pattern that deals with object creation mechanism, trying to create objects in manner that is suitable to the situation”.

The basic form of object creations could result in design problems and result in complex design problems, so to overcome this problem Creational Design Pattern somehow allows you to create the object.

Builder is one of the** Creational Design Pattern**.

When to consider the Builder Design Pattern ?

Builder is useful when you need to do lot of things to build an Object. Let’s imagine DOM (Document Object Model), so if we need to create the DOM, We could have to do lot of things, appending plenty of nodes and attaching attributes to them. We could also imagine about the huge XML Object creation where we will have to do lot of work to create the Object. A Factory is used basically when we could create the entire object in one shot.

As **Joshua Bloch (**He led the Design of the many library Java Collections Framework and many more) – “Builder Pattern is good choice when designing the class whose constructor or static factories would have more than handful of parameters

#java #builder #builder pattern #creational design pattern #design pattern #factory pattern #java design pattern

Joseph  Murray

Joseph Murray

1624442940

Prototype Design Pattern - Java

Prototype design pattern tutorial

Definition of Prototype pattern

The prototype pattern is a creational design pattern in software development. It is used when the type of objects to create is determined by a prototypical instance, which is cloned to produce new objects.

Where to use the Prototype pattern

If the cost for creating a new object is expensive and costs resources.

#java #design-patterns #code #tutorial #prototype-design-pattern #design pattern

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#nature landscapes website design #landscapes website design #website design #website designing #website designer #designer

Composite design pattern — Java

Composite Pattern tutorial

Definition of Composite pattern

In software engineering, the composite pattern is a partitioning design pattern. The composite pattern describes a group of objects that are treated the same way as a single instance of the same type of object. The intent of a composite is to “compose” objects into tree structures to represent part-whole hierarchies. Implementing the composite pattern lets clients treat individual objects and compositions uniformly.

Where to use the Composite pattern?

UML example

Implementation of the Composite pattern

#design-patterns #java #code #composite-design-pattern #tutorial #composite design pattern — java