formatting the source code
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2c9c96a811
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@ -5,37 +5,37 @@ import java.util.Map;
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import java.util.Optional;
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public class HandleOptionalTypeExample {
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static Map<String, User> usersByName = new HashMap();
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static {
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User user1 = new User();
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user1.setUserId(1l);
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user1.setFirstName("baeldung");
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usersByName.put("baeldung", user1);
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}
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public static void main(String[] args) {
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changeUserName("baeldung", "baeldung-new");
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changeUserName("user", "user-new");
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}
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public static void changeUserName(String oldFirstName, String newFirstName) {
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Optional<User> userOpt = findUserByName(oldFirstName);
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if(userOpt.isPresent()){
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User user = userOpt.get();
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user.setFirstName(newFirstName);
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System.out.println("user with name "+oldFirstName+" is changed to "+ user.getFirstName());
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} else {
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//user is missing
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System.out.println("user with name "+oldFirstName+" is not found.");
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}
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}
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public static Optional<User> findUserByName(String name){
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//look up the user in the database, the user object below could be null
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User user=usersByName.get(name);
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Optional<User> opt = Optional.ofNullable(user);
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static Map<String, User> usersByName = new HashMap();
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static {
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User user1 = new User();
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user1.setUserId(1l);
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user1.setFirstName("baeldung");
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usersByName.put("baeldung", user1);
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}
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return opt;
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}
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public static void main(String[] args) {
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changeUserName("baeldung", "baeldung-new");
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changeUserName("user", "user-new");
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}
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public static void changeUserName(String oldFirstName, String newFirstName) {
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Optional<User> userOpt = findUserByName(oldFirstName);
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if (userOpt.isPresent()) {
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User user = userOpt.get();
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user.setFirstName(newFirstName);
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System.out.println("user with name " + oldFirstName + " is changed to " + user.getFirstName());
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} else {
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// user is missing
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System.out.println("user with name " + oldFirstName + " is not found.");
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}
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}
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public static Optional<User> findUserByName(String name) {
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// look up the user in the database, the user object below could be null
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User user = usersByName.get(name);
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Optional<User> opt = Optional.ofNullable(user);
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return opt;
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}
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}
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@ -4,17 +4,16 @@ import com.fasterxml.jackson.core.JsonProcessingException;
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import com.fasterxml.jackson.databind.ObjectMapper;
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public class OptionalToJsonExample {
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public static void main(String[] args) {
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UserOptional user = new UserOptional();
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user.setUserId(1l);
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user.setFirstName("Bael Dung");
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ObjectMapper om = new ObjectMapper();
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try {
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System.out.print("user in json is:"+om.writeValueAsString(user));
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} catch (JsonProcessingException e) {
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// TODO Auto-generated catch block
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e.printStackTrace();
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}
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}
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public static void main(String[] args) {
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UserOptional user = new UserOptional();
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user.setUserId(1l);
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user.setFirstName("Bael Dung");
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ObjectMapper om = new ObjectMapper();
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try {
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System.out.print("user in json is:" + om.writeValueAsString(user));
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} catch (JsonProcessingException e) {
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e.printStackTrace();
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}
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}
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}
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@ -7,20 +7,20 @@ import javax.persistence.EntityManagerFactory;
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import javax.persistence.Persistence;
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public class PersistOptionalTypeExample {
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static String persistenceUnit = "com.baeldung.optionalReturnType";
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static EntityManagerFactory emf = Persistence.createEntityManagerFactory(persistenceUnit);
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static EntityManager entityManager = emf.createEntityManager();
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//to run this app, uncomment the follow line in META-INF/persistence.xml
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//<class>com.baeldung.optionalReturnType.UserOptionalField</class>
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public static void main(String[] args) {
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UserOptionalField user1 = new UserOptionalField();
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user1.setUserId(1l);
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user1.setFirstName(Optional.of("Bael Dung"));
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entityManager.persist(user1);
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UserOptional user2 = entityManager.find(UserOptional.class, 1l);
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System.out.print("User2.firstName:"+user2.getFirstName());
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}
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static String persistenceUnit = "com.baeldung.optionalReturnType";
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static EntityManagerFactory emf = Persistence.createEntityManagerFactory(persistenceUnit);
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static EntityManager entityManager = emf.createEntityManager();
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// to run this app, uncomment the follow line in META-INF/persistence.xml
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// <class>com.baeldung.optionalReturnType.UserOptionalField</class>
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public static void main(String[] args) {
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UserOptionalField user1 = new UserOptionalField();
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user1.setUserId(1l);
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user1.setFirstName(Optional.of("Bael Dung"));
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entityManager.persist(user1);
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UserOptional user2 = entityManager.find(UserOptional.class, 1l);
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System.out.print("User2.firstName:" + user2.getFirstName());
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}
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}
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@ -5,18 +5,18 @@ import javax.persistence.EntityManagerFactory;
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import javax.persistence.Persistence;
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public class PersistOptionalTypeExample2 {
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static String persistenceUnit = "com.baeldung.optionalReturnType";
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static EntityManagerFactory emf = Persistence.createEntityManagerFactory(persistenceUnit);
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static EntityManager em = emf.createEntityManager();
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public static void main(String[] args) {
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UserOptional user1 = new UserOptional();
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user1.setUserId(1l);
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user1.setFirstName("Bael Dung");
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em.persist(user1);
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UserOptional user2 = em.find(UserOptional.class, 1l);
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System.out.print("User2.firstName:"+user2.getFirstName());
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}
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static String persistenceUnit = "com.baeldung.optionalReturnType";
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static EntityManagerFactory emf = Persistence.createEntityManagerFactory(persistenceUnit);
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static EntityManager em = emf.createEntityManager();
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public static void main(String[] args) {
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UserOptional user1 = new UserOptional();
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user1.setUserId(1l);
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user1.setFirstName("Bael Dung");
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em.persist(user1);
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UserOptional user2 = em.find(UserOptional.class, 1l);
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System.out.print("User2.firstName:" + user2.getFirstName());
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}
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}
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@ -5,18 +5,18 @@ import javax.persistence.EntityManagerFactory;
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import javax.persistence.Persistence;
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public class PersistUserExample {
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static String persistenceUnit = "com.baeldung.optionalReturnType";
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static EntityManagerFactory emf = Persistence.createEntityManagerFactory(persistenceUnit);
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static EntityManager em = emf.createEntityManager();
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public static void main(String[] args) {
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User user1 = new User();
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user1.setUserId(1l);
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user1.setFirstName("Bael Dung");
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em.persist(user1);
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User user2 = em.find(User.class, 1l);
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System.out.print("User2.firstName:"+user2.getFirstName());
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}
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static String persistenceUnit = "com.baeldung.optionalReturnType";
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static EntityManagerFactory emf = Persistence.createEntityManagerFactory(persistenceUnit);
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static EntityManager em = emf.createEntityManager();
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public static void main(String[] args) {
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User user1 = new User();
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user1.setUserId(1l);
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user1.setFirstName("Bael Dung");
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em.persist(user1);
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User user2 = em.find(User.class, 1l);
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System.out.print("User2.firstName:" + user2.getFirstName());
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}
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}
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@ -6,37 +6,36 @@ import java.io.ObjectOutputStream;
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import java.util.Optional;
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public class SerializeOptionalTypeExample {
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public static void main(String[] args) {
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User user1 = new User();
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user1.setUserId(1l);
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user1.setFirstName("baeldung");
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serializeObject(user1, "user1.ser");
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public static void main(String[] args) {
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User user1 = new User();
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user1.setUserId(1l);
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user1.setFirstName("baeldung");
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UserOptionalField user2 = new UserOptionalField();
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user2.setUserId(1l);
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user2.setFirstName(Optional.of("baeldung"));
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serializeObject(user2, "user2.ser");
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serializeObject(user1, "user1.ser");
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}
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public static void serializeObject(Object object, String fileName) {
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// Serialization
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try {
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FileOutputStream file = new FileOutputStream(fileName);
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ObjectOutputStream out = new ObjectOutputStream(file);
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out.writeObject(object);
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out.close();
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file.close();
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System.out.println("Object "+object.toString()+ " has been serialized to file "+fileName);
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} catch(IOException e) {
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e.printStackTrace();
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}
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}
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UserOptionalField user2 = new UserOptionalField();
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user2.setUserId(1l);
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user2.setFirstName(Optional.of("baeldung"));
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serializeObject(user2, "user2.ser");
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}
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public static void serializeObject(Object object, String fileName) {
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// Serialization
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try {
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FileOutputStream file = new FileOutputStream(fileName);
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ObjectOutputStream out = new ObjectOutputStream(file);
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out.writeObject(object);
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out.close();
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file.close();
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System.out.println("Object " + object.toString() + " has been serialized to file " + fileName);
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} catch (IOException e) {
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e.printStackTrace();
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}
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}
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}
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@ -7,25 +7,25 @@ import javax.persistence.Id;
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@Entity
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public class User implements Serializable {
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@Id
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private long userId;
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private String firstName;
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public long getUserId() {
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return userId;
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}
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@Id
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private long userId;
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public void setUserId(long userId) {
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this.userId = userId;
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}
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private String firstName;
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public String getFirstName() {
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return firstName;
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}
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public long getUserId() {
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return userId;
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}
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public void setUserId(long userId) {
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this.userId = userId;
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}
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public String getFirstName() {
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return firstName;
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}
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public void setFirstName(String firstName) {
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this.firstName = firstName;
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}
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public void setFirstName(String firstName) {
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this.firstName = firstName;
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}
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}
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@ -9,27 +9,27 @@ import javax.persistence.Id;
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@Entity
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public class UserOptional implements Serializable {
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@Id
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private long userId;
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@Column(nullable = true)
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private String firstName;
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public long getUserId() {
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return userId;
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}
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@Id
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private long userId;
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public void setUserId(long userId) {
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this.userId = userId;
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}
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@Column(nullable = true)
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private String firstName;
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public Optional<String> getFirstName() {
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return Optional.ofNullable(firstName);
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}
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public long getUserId() {
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return userId;
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}
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public void setUserId(long userId) {
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this.userId = userId;
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}
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public Optional<String> getFirstName() {
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return Optional.ofNullable(firstName);
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}
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public void setFirstName(String firstName) {
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this.firstName = firstName;
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Optional.ofNullable(firstName);
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}
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public void setFirstName(String firstName) {
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this.firstName = firstName;
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Optional.ofNullable(firstName);
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}
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}
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@ -8,24 +8,24 @@ import javax.persistence.Id;
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@Entity
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public class UserOptionalField implements Serializable {
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@Id
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private long userId;
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private Optional<String> firstName;
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public long getUserId() {
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return userId;
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}
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@Id
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private long userId;
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public void setUserId(long userId) {
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this.userId = userId;
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}
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private Optional<String> firstName;
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public Optional<String> getFirstName() {
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return firstName;
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}
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public long getUserId() {
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return userId;
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}
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public void setFirstName(Optional<String> firstName) {
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this.firstName = firstName;
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}
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public void setUserId(long userId) {
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this.userId = userId;
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}
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public Optional<String> getFirstName() {
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return firstName;
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}
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public void setFirstName(Optional<String> firstName) {
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this.firstName = firstName;
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}
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}
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