Creational Design Patterns 2 - Builder Design Pattern

Builder design pattern helps creation of an object in a more readable and cleanable way. From the quotes of Gang of four -

“Separate the construction of a complex object from its representation so that the same construction process can create different representations.”

It is helpful when you have an object with different types of parameters .

Ex: lets say that we have an object with four fields , two fields is must to create object and other two fields is optional , we have to pass two mandatory fields in the constructor to create object and other two fields you can ignore .

Lets take example :)

val alertDialog : AlertDialog = AlertDialog.Builder(this)
        .setTitle("Builder Example")
        .setMessage("Builder implementation in Alert Dialog")
        .create();

you can see in above example , this class take context as mandatory parameter and the remaining  parameters (setTitle and setMessage) is optional .

Builder Design Pattern is really great how !?

Consider we have form for user that need to fill his details . there are fields are mandtory and other is optional [name,email,phone] is mandatory and [age,address] is optional .

* First , if we need to make this task without using builder design pattern what will we do :

may the answer will be , you would create constructor with different parameters for creating the object .

With Builder Design Pattern the scenario is very good and helpful , lets go :

public class User{
	

	    private String name;
	    private String email;
	    private String phone;
	    private int age;
	    private String address;
	

	

	    private Student(final StudentBuilder builder) {
	        name = builder.name;
	        email= builder.address;
	        phone= builder.email;
	        age= builder.phoneNumber;
	        address= builder.passportNumber;
	    }
	


	    public static class StudentBuilder {
	        private String name;
	        private String email;
	        private String phone;
	        private String address;
	        private int age;
	

	        public StudentBuilder(String name, String email, String phone){
	            this.name = name;
	            this.address = address;
	            this.email = email;
	        }
	

	        public StudentBuilder setAddress(final String adress) {
	            this.address= address;
	            return this;
	        }
	

	        public StudentBuilder setAge(final int age) {
	            this.age = age;
	            return this;
	        }
	

	        public User create() {
	            return new User(this);
	        }
	    }

	}

Thanks for Reading ......

See you in other Pattern .