Libraries, Frameworks and Patterns - Yash-777/LearnJava GitHub Wiki

Frameworks are concerned with specific application domain

A design pattern is a type of pattern and is more like a concept, whereas a framework is something already coded to be used repetitively.

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A library is also a collection of implementations of behavior, written in terms of a language, that has a well-defined interface by which the behavior is invoked. For instance, people who want to write a higher level program can use a library to make system calls instead of implementing those system calls over and over again.

User will call the library funciton and make use of it. Where as if you are using framework then you use JdbcTemplate class which is provide. But that JdbcTemplate function calls library funcitons and completes the work.

Java - DataBase

SQL with params - RowMapper - Map rocords with pojo class.

jt.update(emp); - pojo class (sql with params taking from pojo calss and mapp records with pojo class)

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Design patterns are the architectural building blocks of frameworks. They help make frameworks extendable and reusable. Frameworks usually contain implementations of many cooperating design patterns. ^{Stack Post}

inversion of control: In a framework, unlike in libraries or in standard user applications, the overall program's flow of control is not dictated by the caller, but by the framework.

Applciation Design and Development Framework:

Spring, Hybernate, Swings, Collections ...

Applciation Testing Framework:

JUnit, TestNG, Selenium

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Factory Design Pattern

SingleTon Design Pattern: Providing single instance of a klass.

Bean Factory Design Pattern: Providing new instance form that klass funciton.

Architectural Design Pattern ^wiki

MVC Pattern^wiki stands for Model-View-Controller Pattern. This pattern is used to separate application's concerns inorder to make code reuse and parallel development.

• Model - The model is the central component of the pattern with the pure application data. Model represents an object or JAVA POJO carrying data.
• A view can be any output representation of information. The View presents the model’s data to the user. View represents the visualization of the data that model contains.
• Controller - Controller acts on both model and view. It controls the data flow into model object and updates the view whenever data changes. It keeps view and model separate.

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• Multipart FileUpload Architecture using Spring Rest API
• JVM Architecture
• Monolithic vs Microservice Architecture ^video
• Model-View-Controller Architecture - MVC

Java OOP concepts
Class  - Collection of a common features of a group of object [static/instance Fields, blocks and Methods]
Object - Instance of a class (instance fields)
Abstraction - Process of hiding complex info and providing required info like API, Marker Interfaces ...
Encapsulation(Security) - Class Binding up with data members(fields) and member functions.
Inheritance  (Reusability by placing common code in single class)
 1. Multilevel - {A -> B -> C} 2. Multiple - Diamond problem {A <- (B) -> C} [Java not supports] 3. Cyclic {A <-> B} [Java not supports]
 * Is-A   Relation - Class A extends B
 * Hash-A Relation - Class A { B obj = new B(); } - (Composition/Aggregation)
Polymorphism (Flexibility) 1. Compile-Time Overloading    2. Runtime Overriding  [Greek - "many forms"]


int[] arr = {1,2,3}; int arrLength = arr.length;   // Fixed length of sequential blocks to hold same data type
String str = "Yash"; int strLength = str.length(); // Immutable Object value can't be changed.

List<?> collections = new ArrayList<String>(); int collectionGroupSize = collections.size();
Map<?, ?> mapEntry = new HashMap<String, String>();
Set<?> keySet = mapEntry.keySet(); // Set of Key's
Set<?> entrySet = mapEntry.entrySet(); // Set of Entries [Key, Value]

// Immutable Objects once created they can't be modified. final class Integer/String/Employee
Integer val = Integer.valueOf("100"); String str2 = String.valueOf(100); // Immutable classes
final class Employee { // All Wrapper classes, java.util.UUID, java.io.File ...
    private final String empName; // Field as Final(values can be assigned only once) Only getter functions.
    public Employee(String name) { this.empName = name; }
}