ConfigOverrideFromCode.java

import com.typesafe.config.Config;
import com.typesafe.config.ConfigFactory;

import java.util.Map;
import java.util.HashMap;

public class ConfigOverrideFromCode {
    static public void main(String[] args) {
        String config = "system {\n" +
                        "   administrator = ${who-knows}\n" +
                        "   developer = ${to-be-assigned-later}\n" +
                        "}";

        Map<String, String> values = new HashMap<String, String>();
        values.put("who-knows", "jon");
        values.put("to-be-assigned-later", "kate");

        Config original = ConfigFactory
                        .parseString(config)
                        .resolveWith(ConfigFactory.parseMap(values));

        System.out.println(original.getString("system.administrator"));
        System.out.println(original.getString("system.developer"));
    }
}