This week's book giveaway is in the OCAJP forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide 1Z0-808 and have Jeanne Boyarsky & Scott Selikoff on-line! See this thread for details.
I am storing the persistent state of thousands of objects for an application in XML. I need to know which of the following 2 methods ould be the fast way to create the objects in memory from the xml representations:
Method #1: Each object is represented in a separate XML text file. The application searches for the object representation based on the name of the XML file. It finds the correct XML file, opens a stream to that file, reads the content, and creates the object in memory using the info in the XML file.
Method #2: Objects are grouped together in a single, massive XML file. Each object is represented by a node or element in the XML file, and each node or element is uniquely identified. The application uses a pull XML parser the read through the file until it reaches the desired node, and uses the information in this node to create the object in memory.
I'm tempted to say that it would be practical tie, but given that Method #1 doesn't do any parsing (rather slow) until it has the file/object it's looking for and Method #2 would be parsing a large file, I'd guess that Method #1 would be faster, the difference increasing as the number of objects grows. Disclaimer: Performance depends on a LOT of variables. There's only one way to be sure: Read Java Platform Performance, write both schemes and test, test, test. Faster still would be to have some sort of in-order index file of the value you are searching on. You could do a binary search of the file using RandomAccessFile. Associated with the index could either a file name or an index into the huge file. Doing a linear search of anything more than a few values will be a big performance drain (see Disclaimer, above).