What could be the use case to return a object in Page Factory design pattern?

Question

I've browsed over internet to get the relevant info but no luck. The example code is given below :

public class HomePage 
{
    @FindBy(id = "fname")
    WebElement name;

    @FindBy(id = "email")
    WebElement email;

    @FindBy(id = "password")
    WebElement password;

    @FindBy(id = "passwordConf")
    WebElement confPassword;

    public HomePage fillFormDetails(String firstname, String emailid)
    {
        name.sendKeys(firstname);
        email.sendKeys(emailid);

        return this;
    }

    public void fillPass(String pass)
    {
        password.sendKeys(pass);

    }   
}

I want to know why we are returning the object while calling fillFormDetails(String firstname, String emailid) method ?

What could be the usecases so we can use this to manage our code efficiency ?

Answer 1

The returned object is used when you want to us methods chaining

HomePage homePage = new HomePage();
homePage
    .fillFormDetails(firstName, email)
    .fillPass(pass);

As a side note, better design is to split all the actions to separated methods, instead of just some of them

public HomePage fillFirstName(String firstName)
{
    name.sendKeys(firstName);

    return this;
}

public HomePage fillEmail(String email)
{
    email.sendKeys(email);

    return this;
}

public void fillPass(String pass)
{
    password.sendKeys(pass);
}

And in the test

HomePage homePage = new HomePage();
homePage
    .fillFirstName(firstName)
    .fillEmail(email)
    .fillPass(pass);