Magento 2 get cart items in block class

Try Following way...

Create Block file

<?php
namespace VendorModuleBlock;

class ShoppingCart extends MagentoFrameworkViewElementTemplate
{
    public function __construct(
        MagentoFrameworkViewElementTemplateContext $context,
        MagentoCheckoutModelSession $checkoutSession,
        array $data = []
    ) {
        $this->_checkoutSession = $checkoutSession;;
        parent::__construct($context, $data);
    }

    /**
     * Get quote object associated with cart. By default it is current customer session quote
     *
     * @return MagentoQuoteModelQuote
     */
    public function getQuoteData()
    {
        $this->_checkoutSession->getQuote();
        if (!$this->hasData('quote')) {
            $this->setData('quote', $this->_checkoutSession->getQuote());
        }
        return $this->_getData('quote');
    }
}

Call in template(.phtml) file,

<?php
// Get all visible items in cart
$quote = $block->getQuoteData();

foreach($quote->getAllVisibleItems() as $_item) {
    echo 'ID: '.$_item->getProductId().'<br/>';
    echo 'Name: '.$_item->getName().'<br/>';
    echo 'Sku: '.$_item->getSku().'<br/>';
    echo 'Quantity: '.$_item->getQty().'<br/>';
    echo 'Price: '.$_item->getPrice().'<br/>';
    echo 'Product Type: '.$_item->getProductType().'<br/>';
    echo 'Discount: '.$_item->getDiscountAmount();echo "<br/>";
}