Java Design Patterns - JDP Series #1

Design patterns are general reusable solutions to common problems that occur in software design. They are not code, but rather guidelines on how to solve a particular problem in a particular context. They are not a finished design that can be transformed directly into code. They are a description or template for how to solve a problem that can be used in many different situations.

Types of design patterns in Java

There are three types of design patterns in Java:

* Creational
* Structural
* Behavioral

Creational design patterns

Creational design patterns are related to the way of creating objects. 
These patterns provide various object creation mechanisms, 
which increase flexibility and reuse of existing code. 
These patterns provide various object creation mechanisms, 
which increase flexibility and reuse of existing code.

There are five types of creational design patterns:

* Singleton Method
* Factory Method
* Abstract Factory Method
* Builder Method
* Prototype Method

Singleton Method
 
Consider a scenario where you need to manage
a configuration file. You need to read the configuration file only 
once and then keep it in memory.
For this, you need to create a class that will read the configuration 
file and keep it in memory.

The below is a PUML diagram for a simple Configuration manager class.

Example: Java Runtime, Logger, Spring Beans, and many more.

Different flavours from JDK.

Runtime.getRuntime();
Desktop.getDesktop();