Parser independent interfaces; parser dependent implementation classes. Most programs must use the parser dependent classes. (JAXP helps solve this.)
Everything's a Node:
Extensive use of polymorphism
Lots of casting
Language independence means there's very limited use of the Java class library; Various features are reinvented
Language independence requires no method overloading because not all languages support it.
Several features are poor design in Java, if not in other languages:
Named constants are often shorts
Only one kind of exception; details provided by constants
No Java-specific utility methods
like equals(), hashCode(), clone(), or
toString()