Can I use both arrays and non-arrays with Apache Commons Config?

Question

With the following properties file:

foo=hello, world!
bar=first,second

I would like to retrieve the first item as a string and the second as an array. I would have thought that getString vs getStringArray would deal with this, but it doesn't - getString("foo") just gets everything before the comma, i.e. "hello".

If I disable delimiter parsing using setDelimiterParsingDisabled, foo is fine, but this also changes the behaviour of getStringArray("bar") to return a single-element array!

I can't find how I can explicitly tell it how I want it to interpret an individual config item, either as a string or as an array. I don't want to put the config items into separate config files with different delimiter rules, and I'd prefer to use a comma as the delimiter for the getStringArray case.

To elaborate, this snippet prints either hello - 2 or hello, world! - 1 - I want it to print hello, world! - 2 !

AbstractFileConfiguration config = new PropertiesConfiguration();
config.setFileName("C:\\temp\\temp.properties");
//config.setDelimiterParsingDisabled(true);
config.load();
System.out.println(config.getString("foo") + " - " + config.getStringArray("bar").length);

Answer 1

As you found out, Commons Config lacks something like a getPlainString() method. Here are some suggestions for workarounds.

I think using a different list delimiter is the easiest to implement. If you need something more complex, consider the other two:

Use a different list delimiter with setListDelimiter()

Works as long as you don't need to interpret the same value as a String and as an array.

properties file:

foo=hello, world!
bar=first;second

Code:

AbstractFileConfiguration config = new PropertiesConfiguration();
config.setFileName("C:\\temp\\temp.properties");
config.setListDelimiter(';');
config.load();
System.out.println(config.getString("foo") + " - " + config.getStringArray("bar").length);

Disable delimiter parsing and do your own splitting

Easily done with String.split(). A simple static method will do:

public static String[] gerStringArray(Configuration config, String key)

Or create a subclass of PropertiesConfiguration and override the getStringArray() and getList() methods.

Use two different configurations

One for settings data where you know what format the data will have. Here you can activate delimiter parsing.

And one for text data where you might have arbitrary data. Here you should deactivate delimiter parsing.

This has the additional advantage of separating settings and text data.

• Not mixing settings and text data keeps both configurations cleaner. Especially if there's a lot of both.
• Often settings data changes depending on the deployment environment (live/test) while text data changes depending on the locale (en_GB/de_DE).