Java Buzz Forum - Builder design pattern in java with example program

Creational patterns helps us to create objects in a manner suitable to the given situation.
Builder design pattern is one of the creational design pattern in java.
Builder design pattern helps us to create complex class object.
Builder design pattern helps us to separate the construction process of a complex object from its representation so that same object construction process can be created in different representations.
Means it will separate complex construction into two parts initialization of class instance and return class instance.
When a class having more number of fields and constructor of that class take care of assigning initial values.
And when we want to create object of the class we need to pass all parameters and should be in same order which constructor is accepting.
Builder design pattern helps us to create same class object by passing required number of fields by using separate builder class object.
Builder design pattern is useful when object creation is very complex.

Advantages of builder design pattern:

Builder design pattern simplifies complex object creation.
Builder design pattern provides separation between instance creation and representation
Re usability

Program #1: Builder design pattern in java with example program

Employee:

EmployeeBuilder

BuilderDemo

To create object of employee class we need to provide all the fields values to the constructor.
So it is somewhat difficult to pass all values all times.
Employee builder class taken all variables of Employee and in setter methods accepts a value and returns EmployeBuilder object.
And EmployeBuilder class has build method which will assign all values to employee and returns Employee object.
Employee empobj= new EmployeeBuilder().setName("Saidesh").setId(1234).build();
Now we create object of Employee class by creating EmployeBuilder class object and caling calling setter methods whatever we have.
Is is very easy to set the values because we have corresponding setter method name is same as variable name.
After setting the values we need to call build method so that it will return employee object with values.


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