How to edit grid items in Magento 2

Create Controller Action Edit

Rsgitech\News\Controller\Adminhtml\Allnews\Edit.php

<?php

namespace Rsgitech\News\Controller\Adminhtml\Allnews;

use Magento\Backend\App\Action;

class Edit extends \Magento\Backend\App\Action
{
	/**
     * Core registry
     *
     * @var \Magento\Framework\Registry
     */
    protected $_coreRegistry;

    /**
     * @var \Magento\Framework\View\Result\PageFactory
     */
    protected $resultPageFactory;

    /**
     * @param Action\Context $context
     * @param \Magento\Framework\View\Result\PageFactory $resultPageFactory
     * @param \Magento\Framework\Registry $registry
     */
    public function __construct(
        Action\Context $context,
        \Magento\Framework\View\Result\PageFactory $resultPageFactory,
        \Magento\Framework\Registry $registry
    ) {
        $this->resultPageFactory = $resultPageFactory;
        $this->_coreRegistry = $registry;
        parent::__construct($context);
    }
	
	/**
     * Authorization level
     *
     * @see _isAllowed()
     */
	protected function _isAllowed()
	{
		return $this->_authorization->isAllowed('Rsgitech_News::save');
	}

    /**
     * Init actions
     *
     * @return \Magento\Backend\Model\View\Result\Allnews
     */
    protected function _initAction()
    {
        // load layout, set active menu and breadcrumbs
        /** @var \Magento\Backend\Model\View\Result\Allnews $resultPage */
        $resultPage = $this->resultPageFactory->create();
        $resultPage->setActiveMenu('Rsgitech_News::news_allnews')
            ->addBreadcrumb(__('News'), __('News'))
            ->addBreadcrumb(__('Manage All News'), __('Manage All News'));
        return $resultPage;
    }

    /**
     * Edit Allnews
     *
     * @return \Magento\Backend\Model\View\Result\Allnews|\Magento\Backend\Model\View\Result\Redirect
     * @SuppressWarnings(PHPMD.NPathComplexity)
     */
    public function execute()
    {
        // 1. Get ID and create model
        $id = $this->getRequest()->getParam('news_id');
        $model = $this->_objectManager->create(\Rsgitech\News\Model\Allnews::class);

        // 2. Initial checking
        if ($id) {
            $model->load($id);
            if (!$model->getId()) {
                $this->messageManager->addError(__('This news no longer exists.'));
                /** \Magento\Backend\Model\View\Result\Redirect $resultRedirect */
                $resultRedirect = $this->resultRedirectFactory->create();
                return $resultRedirect->setPath('*/*/');
            }
        }

        $this->_coreRegistry->register('news_allnews', $model);

        // 5. Build edit form
        /** @var \Magento\Backend\Model\View\Result\Allnews $resultPage */
        $resultPage = $this->_initAction();
        $resultPage->addBreadcrumb(
            $id ? __('Edit News') : __('Add News'),
            $id ? __('Edit News') : __('Add News')
        );
        $resultPage->getConfig()->getTitle()->prepend(__('Allnews'));
        $resultPage->getConfig()->getTitle()
            ->prepend($model->getId() ? $model->getTitle() : __('Add News'));

        return $resultPage;
    }
}
?>

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Create Controller Action InlineEdit

Rsgitech\News\Controller\Adminhtml\Allnews\InlineEdit.php

<?php
namespace Rsgitech\News\Controller\Adminhtml\Allnews;

use Magento\Backend\App\Action\Context;
use Rsgitech\News\Api\AllnewsRepositoryInterface as AllnewsRepository;
use Magento\Framework\Controller\Result\JsonFactory;
use Rsgitech\News\Api\Data\AllnewsInterface;

class InlineEdit extends \Magento\Backend\App\Action
{
    protected $allnewsRepository;

    /**
     * @var \Magento\Framework\Controller\Result\JsonFactory
     */
    protected $jsonFactory;

    public function __construct(
        Context $context,
        AllnewsRepository $allnewsRepository,
        JsonFactory $jsonFactory
    ) {
        parent::__construct($context);
        $this->allnewsRepository = $allnewsRepository;
        $this->jsonFactory = $jsonFactory;
    }
	
	/**
     * Authorization level
     *
     * @see _isAllowed()
     */
	protected function _isAllowed()
	{
		return $this->_authorization->isAllowed('Rsgitech_News::save');
	}

    /**
     * @return \Magento\Framework\Controller\ResultInterface
     */
    public function execute()
    {
        /** @var \Magento\Framework\Controller\Result\Json $resultJson */
        $resultJson = $this->jsonFactory->create();
        $error = false;
        $messages = [];

        $postItems = $this->getRequest()->getParam('items', []);
        if (!($this->getRequest()->getParam('isAjax') && count($postItems))) {
            return $resultJson->setData([
                'messages' => [__('Please correct the data sent.')],
                'error' => true,
            ]);
        }

        foreach (array_keys($postItems) as $newsId) {
            $news = $this->allnewsRepository->getById($newsId);
            try {
                $newsData = $postItems[$newsId];
                $extendedNewsData = $news->getData();
                $this->setNewsData($news, $extendedNewsData, $newsData);
                $this->allnewsRepository->save($news);
            } catch (\Magento\Framework\Exception\LocalizedException $e) {
                $messages[] = $this->getErrorWithNewsId($news, $e->getMessage());
                $error = true;
            } catch (\RuntimeException $e) {
                $messages[] = $this->getErrorWithNewsId($news, $e->getMessage());
                $error = true;
            } catch (\Exception $e) {
                $messages[] = $this->getErrorWithNewsId(
                    $news,
                    __('Something went wrong while saving the news.')
                );
                $error = true;
            }
        }

        return $resultJson->setData([
            'messages' => $messages,
            'error' => $error
        ]);
    }

    protected function getErrorWithNewsId(AllnewsInterface $news, $errorText)
    {
        return '[News ID: ' . $news->getId() . '] ' . $errorText;
    }

    public function setNewsData(\Rsgitech\News\Model\Allnews $news, array $extendedNewsData, array $newsData)
    {
        $news->setData(array_merge($news->getData(), $extendedNewsData, $newsData));
        return $this;
    }
}
?>

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Then run below commands

php bin/magento setup:upgrade
php bin/magetno setup:static-content:deploy
php bin/magento cache:flush

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