Returns true if the named preference node exists in the same tree as this node. Relative path names (which do not begin with the slash character
('/')) are interpreted relative to this preference node.
If this node (or an ancestor) has already been removed with the {@link #removeNode()} method, it is legal to invoke this method,but only with the path name ""; the invocation will return false. Thus, the idiom p.nodeExists("") may be used to test whether p has been removed.
@param pathName the path name of the node whose existenceis to be checked.
@return true if the specified node exists.
@throws BackingStoreException if this operation cannot be completeddue to a failure in the backing store, or inability to communicate with it.
@throws IllegalArgumentException if the path name is invalid (i.e.,it contains multiple consecutive slash characters, or ends with a slash character and is more than one character long).
@throws NullPointerException if path name is null.
@throws IllegalStateException if this node (or an ancestor) has beenremoved with the {@link #removeNode()} method andpathName is not the empty string ("").