There are multiple ways to validate input, and this article will look at two of them: Document Type Definitions (DTD) and XML Schema (XSD).A third option is Relax NG, which tries to find a middle ground between DTD's lack of expressiveness and XSD's Byzantine structure. Before continuing, I want to add a third, non-standard term to describe XML documents: “correct.” A validator can only check the existence, ordering, and general content of an XML file; it's equivalent to the syntax check of a Java compiler.Parser will use a default Error Handler to print the first 10 errors.Please call the 'set Error Handler' method to fix this.A problem occurs when the program has to process documents from multiple sources, which may apply different meaning to elements with the same name: an element from one vendor will be very different from the like-named element from another.Even within an organization, XML data formats can undergo revision, and you may need to handle “version 1” data differently than “version 2.” attributes and does the right thing.For example, XML generated using simple string output in a Windows environment will probably be encoded in .Normally, this isn't an issue, especially if the XML is both produced and processed within the same organization.
” declaration, which must appear before the first element in the document (but after the prologue! The DOCTYPE may specify an embedded DTD, as in the example below, or it may reference an external DTD, as we'll see later. Error Handler was not set, which is probably not what is desired.
Except for one small problem: the Namespace spec was introduced in 1999, while the DOM level 1 spec was released in 1998 and knew nothing of namespaces.
The JDK's XML API predated namespaces, and due to backwards compatibility you must explicitly tell it that you want namespace-aware parsing: , not the parser.
The XML specification requires that an XML document either have a prologue that specifies its encoding, or be encoded in UTF-8 or UTF-16.
But in this example I used a Java String, which is UTF-16 encoded, without a prologue. The answer is that the parser did not read the string directly.