serialization code (#1844)

* adds serialization code

* fixes serialization unit test

* adds code for custom serialization

* changed test case names

* fixes test names

core-java/src/main/java/com/baeldung/serialization/Address.java

@@ -0,0 +1,15 @@
+package com.baeuldung.serialization;
+
+public class Address {
+
+	private int houseNumber;
+
+	public int getHouseNumber() {
+		return houseNumber;
+	}
+
+	public void setHouseNumber(int houseNumber) {
+		this.houseNumber = houseNumber;
+	}
+
+}

core-java/src/main/java/com/baeldung/serialization/Employee.java

@@ -0,0 +1,44 @@
+package com.baeuldung.serialization;
+
+import java.io.IOException;
+import java.io.ObjectInputStream;
+import java.io.ObjectOutputStream;
+import java.io.Serializable;
+
+public class Employee implements Serializable {
+
+	private static final long serialVersionUID = 1L;
+
+	private transient Address address; // not an serializable object
+	private Person person;
+
+	public Address getAddress() {
+		return address;
+	}
+
+	public void setAddress(Address address) {
+		this.address = address;
+	}
+
+	public Person getPerson() {
+		return person;
+	}
+
+	public void setPerson(Person person) {
+		this.person = person;
+	}
+
+	private void writeObject(ObjectOutputStream oos) throws IOException {
+		oos.defaultWriteObject();
+		oos.writeObject(address.getHouseNumber());
+	}
+
+	private void readObject(ObjectInputStream ois) throws ClassNotFoundException, IOException {
+		ois.defaultReadObject();
+		Integer houseNumber = (Integer) ois.readObject();
+		Address a = new Address();
+		a.setHouseNumber(houseNumber);
+		this.setAddress(a);
+	}
+
+}

core-java/src/test/java/com/baeldung/serialization/PersonTest.java

@@ -1,5 +1,5 @@
 package com.baeuldung.serialization;
-import static org.junit.Assert.assertEquals;
+
 import static org.junit.Assert.assertTrue;
 
 import java.io.FileInputStream;
@@ -13,7 +13,7 @@ import org.junit.Test;
 public class PersonTest {
 
 	@Test
-	public void testPeron() throws IOException, ClassNotFoundException   {
+	public void whenSerializingAndDeserializing_ThenObjectIsTheSame() throws IOException, ClassNotFoundException {
 		Person p = new Person();
 		p.setAge(20);
 		p.setName("Joe");
@@ -28,8 +28,37 @@ public class PersonTest {
 		ObjectInputStream objectInputStream = new ObjectInputStream(fileInputStream);
 		Person p2 = (Person) objectInputStream.readObject();
 		objectInputStream.close();
+
 		assertTrue(p2.getAge() == p.getAge());
 		assertTrue(p2.getName().equals(p.getName()));
 	}
 
+	@Test
+	public void whenCustomSerializingAndDeserializing_ThenObjectIsTheSame() throws IOException, ClassNotFoundException {
+		Person p = new Person();
+		p.setAge(20);
+		p.setName("Joe");
+
+		Address a = new Address();
+		a.setHouseNumber(1);
+
+		Employee e = new Employee();
+		e.setPerson(p);
+		e.setAddress(a);
+
+		FileOutputStream fileOutputStream = new FileOutputStream("yofile2.txt");
+		ObjectOutputStream objectOutputStream = new ObjectOutputStream(fileOutputStream);
+		objectOutputStream.writeObject(e);
+		objectOutputStream.flush();
+		objectOutputStream.close();
+
+		FileInputStream fileInputStream = new FileInputStream("yofile2.txt");
+		ObjectInputStream objectInputStream = new ObjectInputStream(fileInputStream);
+		Employee e2 = (Employee) objectInputStream.readObject();
+		objectInputStream.close();
+
+		assertTrue(e2.getPerson().getAge() == e.getPerson().getAge());
+		assertTrue(e2.getAddress().getHouseNumber() == (e.getAddress().getHouseNumber()));
+	}
+
 }