package singleton;

public class AppConfigEager {

    // The JVM creates this instance when the class is first loaded.
    // static guarantees it belongs to the class, not any instance.
    // final guarantees it can never be reassigned.
    private static final AppConfigEager INSTANCE = new AppConfigEager();

    // Private constructor: prevents any other class from calling new AppConfigEager()
    private AppConfigEager() {
        System.out.println("Reading configuration from file...");
        // load properties, set up values, etc.
    }

    // The only way to get the instance
    public static AppConfigEager getInstance() {
        return INSTANCE;
    }

    public String getProperty(String key) {
        return System.getProperty(key, "(not set)");
    }
}