package singleton;

public class Main {
    public static void main(String[] args) {

        System.out.println("--- Implementation 1: Eager ---");
        AppConfigEager eager1 = AppConfigEager.getInstance();
        AppConfigEager eager2 = AppConfigEager.getInstance();
        System.out.println("Same instance? " + (eager1 == eager2));
        System.out.println("db.url = " + eager1.getProperty("db.url"));

        System.out.println("\n--- Implementation 2: Naive Lazy ---");
        AppConfigNaiveLazy lazy1 = AppConfigNaiveLazy.getInstance();
        AppConfigNaiveLazy lazy2 = AppConfigNaiveLazy.getInstance();
        System.out.println("Same instance? " + (lazy1 == lazy2));

        System.out.println("\n--- Implementation 3: Synchronized Method ---");
        AppConfigSynchronized sync1 = AppConfigSynchronized.getInstance();
        AppConfigSynchronized sync2 = AppConfigSynchronized.getInstance();
        System.out.println("Same instance? " + (sync1 == sync2));

        System.out.println("\n--- Implementation 4: Double-Checked Locking ---");
        AppConfigDCL dcl1 = AppConfigDCL.getInstance();
        AppConfigDCL dcl2 = AppConfigDCL.getInstance();
        System.out.println("Same instance? " + (dcl1 == dcl2));

        System.out.println("\n--- Implementation 5: Holder Idiom ---");
        AppConfigHolder holder1 = AppConfigHolder.getInstance();
        AppConfigHolder holder2 = AppConfigHolder.getInstance();
        System.out.println("Same instance? " + (holder1 == holder2));

        System.out.println("\n--- Implementation 6: Enum ---");
        AppConfigEnum enumConfig = AppConfigEnum.INSTANCE;
        System.out.println("db.url = " + enumConfig.getProperty("db.url"));
    }
}