<playlist name="My Playlist"> <tracks> <track [...]/> <track [...]/> </tracks> </playlist>instead of
<playlist name="My Playlist"> <track [...]/> <track [...]/> </playlist>But still: these libraries reduce the amount of code you have to write.
You can store any kind of Text in a properties file. This way, you're able to store numbers as well, but you need to store them as text - just as you have to do with every other text based file format - and you would have to parse them yourself - by calling Integer.parseInt().
Also: the order of the entries in a properties file shouldn't matter at all. You're reading the values using the keys, but you don't have to know the exact order.
Besides Properties, XML, and JSON, there are INI files as well. They are comparable with Properties files, but have some more features (e. g. sections) by default, but the set of features varies depending on the implementation.
And you could use your own file format, but since you would need to implement the file parsing yourself, you should just stick to one of the mentioned file formats.
If you don't know, which format to use for your files: just stick to what you already have (properties I guess) until you encounter some seriour issues regarding the format. Then you'll be able to make a better decision, since you know what problem you'll have to solve with another.