Created files for deep and shallow copy in java

core-java-modules/core-java-lang-oop-patterns/src/main/java/com/baeldung/objectcopy/DeepCopyPerson.java

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+package com.baeldung.objectcopy;
+
+import java.io.*;
+
+class DeepCopyPerson implements Serializable {
+
+    int age;
+
+    public DeepCopyPerson(int age) {
+        this.age = age;
+    }
+
+    public static DeepCopyPerson deepCopy(DeepCopyPerson person) throws IOException, ClassNotFoundException {
+        ByteArrayOutputStream bos = new ByteArrayOutputStream();
+        ObjectOutputStream out = new ObjectOutputStream(bos);
+        out.writeObject(person);
+
+        ByteArrayInputStream bis = new ByteArrayInputStream(bos.toByteArray());
+        ObjectInputStream in = new ObjectInputStream(bis);
+
+        return (DeepCopyPerson) in.readObject();
+    }
+}

core-java-modules/core-java-lang-oop-patterns/src/main/java/com/baeldung/objectcopy/ShallowCopyPerson.java

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+package com.baeldung.objectcopy;
+
+class ShallowCopyPerson {
+
+    int age;
+
+    public ShallowCopyPerson(int age) {
+        this.age = age;
+    }
+}

core-java-modules/core-java-lang-oop-patterns/src/test/java/com/baeldung/objectcopy/DeepCopyPersonUnitTest.java

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+package com.baeldung.objectcopy;
+
+import org.junit.jupiter.api.Test;
+
+import java.io.IOException;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+public class DeepCopyPersonUnitTest {
+
+    @Test
+    public void givenPerson_whenDeepCopy_thenIndependentCopy() throws IOException, ClassNotFoundException {
+        DeepCopyPerson person1 = new DeepCopyPerson(30);
+        DeepCopyPerson person2 = DeepCopyPerson.deepCopy(person1);
+        person1.age = 25;
+
+        assertEquals(30, person2.age);
+    }
+}

core-java-modules/core-java-lang-oop-patterns/src/test/java/com/baeldung/objectcopy/ShallowCopyPersonUnitTest.java

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+package com.baeldung.objectcopy;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+public class ShallowCopyPersonUnitTest {
+
+    @Test
+    public void givenPerson_whenShallowCopy_thenSharedReference() {
+        ShallowCopyPerson person1 = new ShallowCopyPerson(30);
+        ShallowCopyPerson person2 = person1;
+        person1.age = 25;
+
+        assertEquals(25, person2.age);
+    }
+}