how to get html class values using regular expression in ruby

how to get html class values using regular expression in ruby

I have this below string from which I want to extract class values "ruby",
"html", "java"
<div class="ruby" name="ruby_doc">
<div class="html" name="html_doc">
<div class="java" name="java_doc">
This is what I have so far
str = <<END
<div class="ruby" name="ruby_doc">
<div class="html" name="html_doc">
<div class="java" name="java_doc">
END
str.scan(/"[^"]+/) #=> returns
["\"ruby", "\" name=", "\"ruby_doc", "\">\n<div class=", "\"html",...]
str.scan(/class="[^"]+/) #=> ["class=\"ruby", "class=\"html", "class=\"java"]