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Context:-   

The main aim of OOP is to bind together the data and the functions that operate on them so that no other part of the code can access this data except that function of the class.

So, we can build the real-time big applications by using the classes, methods, access specifiers, access modifiers, hiding data, showing data, extend the additional code with another class

OOP is a type of software design this design will useful for programming approach

And it is well suited for programs that are large, complex, actively updated and well-maintained projects.

How it works:-

A class that contains planning to to-do the work. And it doesn’t consume any space in memory of the machine

After you execute a class it will convert into the object and takes space in memory of the machine

The class structure is for code re-usability means the superclass is allowed to inherit the features of methods and variables of the superclass (parent class).

A feature of objects is an object’s procedures that can access and often modify the data fields of the object with which they are associated

Examples:-

A civil engineer gives a plan of design for building a house on a chart (CLASS). Then the workers will build the real house according to design (OBJECT).

Similarly, a programmer can give the class a logical structure text in a file (CLASS). Then after the system will run on execution and create data in memory according to login given (OBJECT).

Class:-

Class is a text which consists of the logical operations of the object.

And class can be extended with other classes using specific keywords

That class extension is useful for the project without affecting the entire core project.

And it also useful to debug the newly updated classes

The class consists mainly

1. Variables
2. Methods

The class architecture will like the variables can handle the data

Syntax:

1. class<class_name>{
2. variable;
3. method;
4. }

In all object-oriented programming languages fallowing the same structure of the class

1. Classes
2. Interfaces

Access Specifiers in class:-

Inside of the class, all are class variables

Inside of the method all are method variables

In programming, we can divide the variables and methods with access specifiers

1. public
2. private
3. protected

1. Public 
2. Can access to other classes

1. Private 
2. Will hide the data in the current class itself.

1. Protected 
2. Will show data to the base class and derived-class only except all other classes it will hide

Method:

The main aim of the method is for writing a specific piece of code and returning its output

It’s always possible to build great things with certain blocks with a clear blueprint

Making everything is possible with clear objects

1. The method is a part of the class. A class can be full filled with n number of methods
2. A method can get the inputs through the parentheses and produces output when it gets called.
3. A method is a set of code wizard

Example:-

In mathematics, we have the functions like f(x) = x*x same concept in programming implemented

Simpler a function in the program is a block of code performs a specific task and returns task output

Syntax:

1. class<class_name>{
2. function <method_name>(inputs){
3. //task logic
4. //return logic output
5. }
6. }

Object:

We use a specific keyword for converting class into the object.

After converting into the object all methods and variables will become the properties of the object

So, we could create the unique name of n number of objects with a different name

And also could interact with other objects with unique names

Conclusion:-

1. This is about the main theme of object-oriented programming.
2. For security purpose, access specifiers and access modifiers are implemented in object-oriented programming

And the architecture of object-oriented programming like the following.

1. A class build with piece of code with certain methods, and variables
2. All of those pieces of classes will build packages or modules.
3. All of these modules or packages will build the entire project.

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Lombok is a open source library (basically a standalone jar) which is capable of doing magic in automating the boilerplate code generation for any java class. So if Lombok is in classpath, it can easily get rid of all the getters & setters methods, class constructors, hashcode and equals methods and many more by just adding couple of annotations the class.

Install Lombok in Eclipse

First we need to download the Lombok jar. We can directly download it from lombok site but as we will use maven in future, so let’s maven do the download on our behalf, otherwise we will have multiple version of same jar in machine which will create problem when we will have to use updated version of the it.

Create you are maven project in eclipse and below depedency in pom.xml file.

<dependency>
   <groupId>org.projectlombok</groupId>
   <artifactId>lombok</artifactId>
   <version>1.16.18</version>
</dependency>

Start Lombok Installation

Once the jar downloaded in System , goto the jar location from command prompt and run the following command java -jar lombok-1.16.18.jar and we should be greeted by Lombok installation window provided by lombok like this.

Give Lombok Install Path

Now click on the “Specify Location” button and locate the eclipse.exe path under eclipse installation folder like this.

Finish Lombok Installation

Now we need to finally install this by clicking the “Install/Update” button and we should finished installing lombok in eclipse and we are ready to use its hidden power. Final screen will look like,

Lombok Examples

Get rid of Setters and Getters :

We all have to generate this java bean pattern heavily in day to day work and it has become so popular that all the IDEs have given feature to generate the Getters and Setters – but once generated by IDE, what’s next? we need to carry those code in whole lifetime of the project and we need to maintain those and it also increases the line of code of the whole project.

With lombok, we need to add few annotations in the class and we are done. To generate Setters and Getters we need to just add @Getter and @Setter at the class level like this.

import lombok.Getter;
import lombok.NonNull;
import lombok.Setter;

@Getter
@Setter
public class LombokModel {

   private @NonNull String name;
   private @NonNull String age;
   private @NonNull String address;

   // No Getters and Setters, hashCode, Equal-- even though we can refer it from client code.
   // This is how we are taking help from Lombok to get rid of boiler plate code.
}  

Generating Constructors :

Lombok can easily generate the constructors, both no arguments and with fields. We need to add annotation @NoArgsConstructor to generate the implicit no argument constructor and @RequiredArgsConstructor to add required field constructor.

Also, to make a field required, we need to add @NonNull in the field itself like below.

import lombok.Getter;
import lombok.NoArgsConstructor;
import lombok.NonNull;
import lombok.RequiredArgsConstructor;
import lombok.Setter;

@Getter
@Setter
@NoArgsConstructor
@RequiredArgsConstructor
public class LombokModel {

   private @NonNull String name;
   private @NonNull String age;
   private @NonNull String address;

}

Other Lombok Features

We have few more annotations, which are also very useful as well. Those are left for you to try and play with. e.g.

1. @Data
2. @Delegate
3. @Synchronized
4. @Slf4j
5. @Cleanup
6. @EqualsAndHashCode
7. @ToString

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