How controller loads the layout in magento 2 - layout

Question

I have developed a sample module in magento 2 that just prints the hellow world.there is only one controller and one layout file
controller
<?php
namespace MageClass\First\Controller\Test;
use Magento\Framework\View\Result\PageFactory;
use Magento\Framework\App\Action\Context;
class Helloworld extends \Magento\Framework\App\Action\Action
{
public function execute()
{
$this->_view->loadLayout();
$this->_view->renderLayout();
}
}
layout file
<page xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" layout="1column" xsi:noNamespaceSchemaLocation="../../../../../../../lib/internal/Magento/Framework/View/Layout/etc/page_configuration.xsd">
<referenceBlock name="content">
<block
template="helloworld.phtml"
class="Akhil\Test\Block\Helloworld"
name="helloworld_test_helloworld">
</block>
</referenceBlock>
</page>
Here my doubt is how this layout and controller is linked .when i accessed controller through browser by default this layout is loading. How it's linking layout and controller.
and i want to add another layout and controller in my module.so how to link these as when accessed the controller load the required layout

Answer 1

In Magento 2 Controller and layout file linked together with their
naming conventions.
So here you have created your controller file which is : app/code/MageClass/First/Controller/Test/Helloworld.php
Your layout file name is : app/code/MageClass/First/View/forntend/layout/helloworld_tes‌​t_helloworld.xml
Layout file name always depends on the controller name and its action
name.
Naming convention of layout file is - modulename_controllername_actionname.xml
Example 1:
Here your module name is "Helloworld" controller name is "Test" and your action name is "Helloworld".
so your layout file name should be - helloworld_test_helloworld.xml(modulename_controllername_actionname.xml)
Same thing now if you want to create new controller and new layout then again you need to like that using above conventions
Example :2
Here i am creating second controller "Test1" and action "Helloworld1".
so your controller path should be - app/code/MageClass/First/Controller/Test1/Helloworld1.php
so here your layout file name should be - helloworld_test1_helloworld1.xml(modulename_controllername_actionname.xml)
More reference refer this link - http://devdocs.magento.com/guides/v2.0/frontend-dev-guide/layouts/layout-types.html