How to check if woocommerce is activated in theme

I’m creating a theme with woocommerce which has the following:

    <ul>
              <li>
                     <?php if ( is_user_logged_in() ) { ?>
<a href="<?php echo get_permalink( get_option('woocommerce_myaccount_page_id') ); ?>" title="<?php _e('My Account','woothemes'); ?>"><?php _e('My Account','woothemes'); ?></a>
<?php }
else { ?>
<a href="<?php echo get_permalink( get_option('woocommerce_myaccount_page_id') ); ?>" title="<?php _e('Sign-in','woothemes'); ?>"><?php _e('Sign-in','woothemes'); ?></a>
<?php } ?>
                </li>
                                                <li><a href="<?php echo get_option('home').'/'.'my-lists/'?>" title="My Wishlist">Wishlist</a></li>

<!--                <li><a href="#" title="Email updates">Email Updates</a></li>
-->                <li> <?php global $woocommerce; ?>

<a id="header-ShoppingCart" class="cart-contents" href="<?php echo $woocommerce->cart->get_cart_url(); ?>" title="<?php _e('View your shopping cart', 'woothemes'); ?>"><?php echo sprintf(_n('%d item', 'My Bag (%d)', $woocommerce->cart->cart_contents_count, 'woothemes'), $woocommerce->cart->cart_contents_count);?> - <span id="header-cartCount"><?php echo $woocommerce->cart->get_cart_total(); ?></span></a>

           </li>

            </ul>

However this breaks the site if the woocommerce plugin is not activated. How can I check if the woocommerce plugin is activated?

Solutions Collecting From Web of "How to check if woocommerce is activated in theme"

You could check to see if the ‘WooCommerce’ class exists, then run the code that requires WooCommerce.

<?php
if ( class_exists( 'WooCommerce' ) ) {
  // code that requires WooCommerce
} else {
  // you don't appear to have WooCommerce activated
}
?>

To check if woocommerce or anyother plguin is active, paste the following code on the template where you want to display the message.

if ( in_array( 'woocommerce/woocommerce.php', apply_filters( 'active_plugins', get_option( 'active_plugins' ) ) ) ) {
    echo 'WooCommerce is active.';
} else {
    echo 'WooCommerce is not Active.';
}

Use following code. It will work on multi site also.

include_once( ABSPATH . 'wp-admin/includes/plugin.php' );
if(is_plugin_active( 'woocommerce/woocommerce.php')) return;