public class SingletonOnDemand { private SingletonOnDemand () {} private static class Singleton { private static final SingletonOnDemand instance = new SingletonOnDemand(); } public static SingletonOnDemand getInstance () { System.out.println("create instance"); return Singleton.instance; } }
public class SingletonClass { private static final SingletonClass SINGLE_INSTANCE = new SingletonClass(); private SingletonClass() {} public static SingletonClass getInstance() { return SINGLE_INSTANCE; } }