Fluent Interface

 Fluent Interface was coined by Martin Fowler and Eric Evans.This makes code easy to read and is implemented by method chaining.

Example: consider a Person class

Person.java

package com.sandhya;


public class Person {

    private String name;
    private int age;
    private double salary;

    public Person(String name, int age, double salary)
    {
        this.name = name;
        this.age = age;
        this.salary = salary;
    }

    public void setName(String name)
    {
        this.name = name;
    }

    public String getName()
    {
        return this.name;
    }

    public void setAge(int age)
    {
        this.age = age;
    }

    public int getAge()
    {
        return this.age;
    }

    public void setSalary(double salary)
    {
        this.salary = salary;
    }

    public double getSalary()
    {
        return this.salary;
    }


}

PersonBuilder.java

package com.sandhya;

public class PersonBuilder {

    private String name;
    private int age;
    private double salary;

    public PersonBuilder()
    {
    }

    public PersonBuilder setName(String name)
    {
        this.name = name;
        return this;
    }

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

    public PersonBuilder setSalary(double salary)
    {
        this.salary = salary;
        return this;
    }

    public Person toPerson()
    {
        Person p = new Person(name,age,salary);
        return p;
    }


}

In PersonBuilder class setter methods returns current instance of PersonBuilder. Because of this ,methods can be called as a chain.

PersonBuilder builder = new PersonBuilder()
        .setName("Sidharth")
        .setAge(10)
        .setSalary(20000);

Main.java

package com.sandhya;

public class Main {

    public static void main(String[] args)
    {
        PersonBuilder builder = new PersonBuilder()
                .setName("Sidharth")
                .setAge(10)
                .setSalary(20000);
        Person p = builder.toPerson();
        System.out.println("Name:"+p.getName() +
                " Age:"+p.getAge()+
                " Salary:"+p.getSalary());

    }

}