Problem

You have a parsed document that you would like to update attribute values on, before saving it out to disk, or sending it on as a HTTP response.

Solution

Use the attribute setter methods Element.attr(String key, String value), and Elements.attr(String key, String value).

If you need to modify the class attribute of an element, use the Element.addClass(String className) and Element.removeClass(String className) methods.

The Elements collection has bulk attribue and class methods. For example, to add a rel="nofollow" attribute to every a element inside a div:

doc.select("div.comments a").attr("rel", "nofollow");

Description

Like the other methods in Element, the attr methods return the current Element (or Elements when working on a collection from a select). This allows convenient method chaining:

doc.select("div.masthead").attr("title", "jsoup").addClass("round-box");