Question

Is it possible to create a new properties file and add keys and values in run time?
I want to add new keys to properties file depending on user input while installing my application. I checked out Java Properties class but it seem it can set values to existing keys but can not add new keys to properties file.

Answer 1

You can add new properties just by calling setProperty with a key which doesn’t currently exist. That will only do it in memory though – you’ll have to call store again to reflect the changes back to a file:

Properties prop = new Properties();
prop.load(...); // FileInputStream or whatever

prop.setProperty("newKey", "newValue");
prop.store(...); // FileOutputStream or whatever