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Creating a Deep vs Shallow Copy of an Object in Java by amitkumar88265@gmail.com #12733

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Creating a Deep vs Shallow Copy of an Object in Java by amitkumar88265@gmail.com #12733

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67da130
added author and blog class and a test class BlogTest to show deep an…
Sep 15, 2022
38a5750
added a new assertion
Sep 15, 2022
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31 changes: 31 additions & 0 deletions ...ules/core-java-lang-oop-patterns/src/main/java/com/baeldung/deep_shallow_copy/Author.java
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package com.baeldung.deep_shallow_copy;

/**
* @author amitkumar
*/

public class Author {
private String firstName;
private String lastName;

public Author(String firstName, String lastName) {
this.firstName = firstName;
this.lastName = lastName;
}

public String getFirstName() {
return firstName;
}

public void setFirstName(String firstName) {
this.firstName = firstName;
}

public String getLastName() {
return lastName;
}

public void setLastName(String lastName) {
this.lastName = lastName;
}
}
55 changes: 55 additions & 0 deletions ...odules/core-java-lang-oop-patterns/src/main/java/com/baeldung/deep_shallow_copy/Blog.java
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package com.baeldung.deep_shallow_copy;

/**
* @author amitkumar
*/
public class Blog implements Cloneable {
private String title;
private String content;
private Author author;

public Blog(String title, String content, Author author) {
this.title = title;
this.content = content;
this.author = author;
}

public Blog createCopy() {
Author author = this.getAuthor();
return new Blog(this.getTitle(), this.getContent(), new Author(author.getFirstName(), author.getLastName()));
}

public String getTitle() {
return title;
}

public void setTitle(String title) {
this.title = title;
}

public String getContent() {
return content;
}

public void setContent(String content) {
this.content = content;
}

public Author getAuthor() {
return author;
}

public void setAuthor(Author author) {
this.author = author;
}

@Override
protected Object clone() throws CloneNotSupportedException {
Author author = new Author(this.getAuthor()
.getFirstName(), this.getAuthor()
.getLastName());
Blog cloned = (Blog) super.clone();
cloned.setAuthor(author);
return cloned;
}
}
88 changes: 88 additions & 0 deletions ...es/core-java-lang-oop-patterns/src/test/java/com/baeldung/deep_shallow_copy/BlogTest.java
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package com.baeldung.deep_shallow_copy;

import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.assertNotEquals;

import org.junit.jupiter.api.Test;

/**
* @author amitkumar
*/
class BlogTest {

@Test
public void whenObjectIsCopiedUsingReference_thenShallowCopyIsCreated() {
Blog blog = new Blog("Effective Jave", "some content", new Author("Joshua", "Bloch"));
Blog newBlog = blog;
assertEquals(blog.getContent(), newBlog.getContent());
assertEquals(blog.getTitle(), newBlog.getTitle());
assertEquals(blog.getAuthor()
.getFirstName(), newBlog.getAuthor()
.getFirstName());
assertEquals(blog.getAuthor()
.getLastName(), newBlog.getAuthor()
.getLastName());
blog.setContent("new Content");
assertEquals(blog.getContent(), newBlog.getContent());
newBlog.setTitle("new Title");
assertEquals(blog.getTitle(), newBlog.getTitle());
}

@Test
public void whenObjectIsCopiedUsingCopyConstructor_thenDeepCopyIsCreated() {
Blog blog = new Blog("Effective Jave", "some content", new Author("Joshua", "Bloch"));
Blog newBlog = blog.createCopy();
assertEquals(blog.getContent(), newBlog.getContent());
assertEquals(blog.getTitle(), newBlog.getTitle());
assertEquals(blog.getAuthor()
.getFirstName(), newBlog.getAuthor()
.getFirstName());
assertEquals(blog.getAuthor()
.getLastName(), newBlog.getAuthor()
.getLastName());
blog.setContent("new Content");
assertNotEquals(blog.getContent(), newBlog.getContent());
newBlog.setTitle("new Title");
assertNotEquals(blog.getTitle(), newBlog.getTitle());
}

@Test
public void whenObjectIsCopiedUsingDefaultOverriddenCloneMethod_thenShallowCopyIsCreated() throws CloneNotSupportedException {
Blog blog = new Blog("Effective Jave", "some content", new Author("Joshua", "Bloch"));
Blog newBlog = (Blog) blog.clone();
assertEquals(blog.getContent(), newBlog.getContent());
assertEquals(blog.getTitle(), newBlog.getTitle());
assertEquals(blog.getAuthor()
.getFirstName(), newBlog.getAuthor()
.getFirstName());
assertEquals(blog.getAuthor()
.getLastName(), newBlog.getAuthor()
.getLastName());
blog.getAuthor()
.setLastName("last name");
assertNotEquals(blog.getAuthor()
.getLastName(), newBlog.getAuthor()
.getLastName());
}

@Test
public void whenObjectIsCopiedUsingCustomOverriddenCloneMethod_thenDeepCopyIsCreated() {
Blog blog = new Blog("Effective Jave", "some content", new Author("Joshua", "Bloch"));
Blog newBlog = blog.createCopy();
assertEquals(blog.getContent(), newBlog.getContent());
assertEquals(blog.getTitle(), newBlog.getTitle());
assertEquals(blog.getAuthor()
.getFirstName(), newBlog.getAuthor()
.getFirstName());
assertEquals(blog.getAuthor()
.getLastName(), newBlog.getAuthor()
.getLastName());
blog.setContent("new Content");
assertNotEquals(blog.getContent(), newBlog.getContent());
newBlog.setTitle("new Title");
assertNotEquals(blog.getTitle(), newBlog.getTitle());
blog.getAuthor().setLastName("last name");
assertNotEquals(blog.getAuthor().getLastName(), newBlog.getAuthor().getLastName());
}

}