How to load multiple configuration files using apache common configuration(java)

Question

I have a main conf file which I load using apache common configuration class. I have a requirement where user can specify a conf file and values in those file will override the

Answer 1

PropertiesConfiguration has a method copy(Configuration c) which copies the content of the specified configuration into this configuration. If the specified configuration contains a key that is also present in this configuration, the value of this key will be replaced by the new value.

Answer 2

I think you want something similar to the mechanism described here:

CompositeConfiguration config = new CompositeConfiguration();
config.addConfiguration(new PropertiesConfiguration("user.properties"));
config.addConfiguration(
    new PropertiesConfiguration("application.properties"));
// user preferences have precedence over application preferences

Reference:

• CompositeConfiguration

Answer 3

With cfg4j:

// Specify which files to load. Configuration from both files will be merged.
ConfigFilesProvider configFilesProvider = () -> Arrays.asList(new File("application.properties"), new File("otherConfig.properties"));

// Use local files as configuration store
ConfigurationSource source = new FilesConfigurationSource(configFilesProvider);

Then use it in a standard way to get properties out.