Roll Your Own Swing-based XML Editor (Part I)

Editor’s note: This is the first of a three-part series about how to build your own XML editor.

f you’ve been looking for a cross-platform, open-source XML editor, you’ve likely come up short. In the following series of three articles, I will walk you through the development of a simple, no frills, XML editor, utilizing several of the most common Java 2 Swing components. This series will be beneficial to anyone wanting to write their own XML editor, or just to those of you looking to learn or brush up on Swing.

In this first article, we will briefly discuss XML and why a tree structure is appropriate to display XML, and then we will take a look at the JAXP API and how to set up your environment with the necessary XML classes. Then we will learn about the JTree Swing component that displays a graphical tree (a common component in many XML editors). Finally, we will build a reusable class that extends the JTree component that is capable of parsing an XML document and displaying its data in a JTree.

In the second article, we will create the framework for our XML editor. In order to do so, we will cover a variety of Swing components (including JSplitPanes, JScrollPanes, JButtons, and JTextAreas).

In the third and final article, we will add the finishing touches to our editor by building a JMenu component and adding it to the editor. Additionally, we will construct JFileChooser components to access the underlying file system to allow XML documents to be saved and new documents to be opened.



How can I create a visual representation of an XML document?



Create a custom class that extends JTree, capable of parsing an XML file into a DOM object and constructing a JTree from that object.

Handling XML Data
(Editor’s note: If you already know how to work with XML data and you have downloaded the latest version of the xerces.jar from the Apache Group, then you may move on to the next page.)

One of the most common misunderstandings about the eXtensible Markup Language (XML) is that it is a new way of displaying data in a Web browser, akin to HTML or Cascading Style Sheets (CSS). The truth is that XML is a data-representation language, not a data-presentation language. It allows you to describe your data in a meaningful way. XML enables you to declare that “these three words constitute a heading,” “this is the byline,” and “this section constitutes the article body.” XML allows you to declare what a particular piece of data is, rather than how that data should appear in a Web page.

Consider the following XML sample:

 Kyle Gabhart	

This is the article body

Notice that these elements are different from standard HTML, but they look similar to HTML. This is because both HTML and XML have the same origin, SGML. The difference is that HTML has a predefined tag set, and XML’s grammar is flexible, allowing you to surround data with a meaningful tag (like ). Also notice, the way in which every element descends from the root element (