String s = config.getString("path.to.string");
int i = config.getInt("path.to.int");
double d = config.getDouble("path.to.double");
List<String> sl = config.getStringList("path.to.stringlist");
List<Double> dl = config.getDoubleList("path.to.doublelist");
List<Integer> il = config.getIntegerList("path.to.integerlist");
The Bukkit configuration files are straight-forward Y.A.M.L (Yet Another Markup Language) files, and are implemented as so.