Calling static method in the Widget Class

I have a widget

class Xwidget extends WP_Widget{
function cron_addB(){}

}

I want to run a cron job that calls that function from outside the class

function xxx_cron_activation() {   ;
    if ( !wp_next_scheduled( 'xxx_followers' ) ) {
    wp_schedule_event(time(), 'hourly', 'xxx_followers');
}
}
add_action('wp', 'xxx_cron_activation');

add_action('xxx_followers',array('Xwidget',"cron_addB"));

Cron is being triggered but the function is not being executed

Try this instead:

$gloabl $myxclass;
$myxclass = new Xwidget();
add_action( 'xxx_followers', array(&$myxclass, "cron_addB" ) );

or

add_action('xxx_followers', "init_xclass_and_cron");
function init_xclass_and_cron() {
    $myxclass = new Xwidget();
    $myxclass->cron_addB();
}