public class Singleton { // Private static instance variable to hold the single instance private static Singleton instance; // Private constructor to prevent instantiation from other classes private Singleton() { // Initialization code, if needed } // Public static method to get the single instance public static Singleton getInstance() { if (instance == null) { instance = new Singleton(); } return instance; } // Other methods of the Singleton class public void showMessage() { System.out.println("Hello, I am a Singleton!"); } }public class SingletonClass { private static final SingletonClass SINGLE_INSTANCE = new SingletonClass(); private SingletonClass() {} public static SingletonClass getInstance() { return SINGLE_INSTANCE; } }public class SingletonSerializedTest { public static void main(String[] args) throws FileNotFoundException, IOException, ClassNotFoundException { SerializedSingleton instanceOne = SerializedSingleton.getInstance(); ObjectOutput out = new ObjectOutputStream(new FileOutputStream( "filename.ser")); out.writeObject(instanceOne); out.close(); // deserialize from file to object ObjectInput in = new ObjectInputStream(new FileInputStream( "filename.ser")); SerializedSingleton instanceTwo = (SerializedSingleton) in.readObject(); in.close(); System.out.println("instanceOne hashCode="+instanceOne.hashCode()); System.out.println("instanceTwo hashCode="+instanceTwo.hashCode()); } }synchoronizedpublic class Singleton { private static Singleton instance; private Singleton() {} public static Singleton getInstance() { if (instance == null) { instance = new Singleton(); } return instance; } }