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[JAVA-621] core-java-lang-oop-patterns module

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* Creation

* Moved code from https://www.baeldung.com/java-composition-aggregation-association

* Moved code from https://www.baeldung.com/java-inheritance-composition

* Moved code from https://www.baeldung.com/java-immutable-object

* Moved code from https://www.baeldung.com/java-deep-copy

* Moved article references to the new README.md
This commit is contained in:
dupirefr
2020-04-02 21:24:31 +02:00
parent 29a0cc015f
commit af08d3814b
38 changed files with 55 additions and 3 deletions
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59
core-java-modules/core-java-lang-oop/src/main/java/com/baeldung/deepcopy/Address.java
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@@ -1,59 +0,0 @@
package com.baeldung.deepcopy;
import java.io.Serializable;
public class Address implements Serializable, Cloneable {
@Override
public Object clone() {
try {
return (Address) super.clone();
} catch (CloneNotSupportedException e) {
return new Address(this.street, this.getCity(), this.getCountry());
}
}
private static final long serialVersionUID = 1740913841244949416L;
private String street;
private String city;
private String country;
public Address(Address that) {
this(that.getStreet(), that.getCity(), that.getCountry());
}
public Address(String street, String city, String country) {
this.street = street;
this.city = city;
this.country = country;
}
public Address() {
}
public String getStreet() {
return street;
}
public String getCity() {
return city;
}
public String getCountry() {
return country;
}
public void setStreet(String street) {
this.street = street;
}
public void setCity(String city) {
this.city = city;
}
public void setCountry(String country) {
this.country = country;
}
}

48
core-java-modules/core-java-lang-oop/src/main/java/com/baeldung/deepcopy/User.java
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@@ -1,48 +0,0 @@
package com.baeldung.deepcopy;
import java.io.Serializable;
public class User implements Serializable, Cloneable {
private static final long serialVersionUID = -3427002229954777557L;
private String firstName;
private String lastName;
private Address address;
public User(String firstName, String lastName, Address address) {
this.firstName = firstName;
this.lastName = lastName;
this.address = address;
}
public User(User that) {
this(that.getFirstName(), that.getLastName(), new Address(that.getAddress()));
}
public User() {
}
@Override
public Object clone() {
User user;
try {
user = (User) super.clone();
} catch (CloneNotSupportedException e) {
user = new User(this.getFirstName(), this.getLastName(), this.getAddress());
}
user.address = (Address) this.address.clone();
return user;
}
public String getFirstName() {
return firstName;
}
public String getLastName() {
return lastName;
}
public Address getAddress() {
return address;
}
}

137
core-java-modules/core-java-lang-oop/src/test/java/com/baeldung/deepcopy/DeepCopyUnitTest.java
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@@ -1,137 +0,0 @@
package com.baeldung.deepcopy;
import static org.assertj.core.api.Assertions.assertThat;
import java.io.IOException;
import org.apache.commons.lang3.SerializationUtils;
import org.junit.Ignore;
import org.junit.Test;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.google.gson.Gson;
public class DeepCopyUnitTest {
@Test
public void whenCreatingDeepCopyWithCopyConstructor_thenObjectsShouldNotBeSame() {
Address address = new Address("Downing St 10", "London", "England");
User pm = new User("Prime", "Minister", address);
User deepCopy = new User(pm);
assertThat(deepCopy).isNotSameAs(pm);
}
@Test
public void whenModifyingOriginalObject_thenCopyShouldNotChange() {
Address address = new Address("Downing St 10", "London", "England");
User pm = new User("Prime", "Minister", address);
User deepCopy = new User(pm);
address.setCountry("Great Britain");
assertThat(deepCopy.getAddress().getCountry()).isNotEqualTo(pm.getAddress().getCountry());
}
@Test
public void whenModifyingOriginalObject_thenCloneCopyShouldNotChange() {
Address address = new Address("Downing St 10", "London", "England");
User pm = new User("Prime", "Minister", address);
User deepCopy = (User) pm.clone();
address.setCountry("Great Britain");
assertThat(deepCopy.getAddress().getCountry()).isNotEqualTo(pm.getAddress().getCountry());
}
@Test
public void whenModifyingOriginalObject_thenCommonsCloneShouldNotChange() {
Address address = new Address("Downing St 10", "London", "England");
User pm = new User("Prime", "Minister", address);
User deepCopy = (User) SerializationUtils.clone(pm);
address.setCountry("Great Britain");
assertThat(deepCopy.getAddress().getCountry()).isNotEqualTo(pm.getAddress().getCountry());
}
@Test
public void whenModifyingOriginalObject_thenGsonCloneShouldNotChange() {
Address address = new Address("Downing St 10", "London", "England");
User pm = new User("Prime", "Minister", address);
Gson gson = new Gson();
User deepCopy = gson.fromJson(gson.toJson(pm), User.class);
address.setCountry("Great Britain");
assertThat(deepCopy.getAddress().getCountry()).isNotEqualTo(pm.getAddress().getCountry());
}
@Test
public void whenModifyingOriginalObject_thenJacksonCopyShouldNotChange() throws IOException {
Address address = new Address("Downing St 10", "London", "England");
User pm = new User("Prime", "Minister", address);
ObjectMapper objectMapper = new ObjectMapper();
User deepCopy = objectMapper.readValue(objectMapper.writeValueAsString(pm), User.class);
address.setCountry("Great Britain");
assertThat(deepCopy.getAddress().getCountry()).isNotEqualTo(pm.getAddress().getCountry());
}
@Test
@Ignore
public void whenMakingCopies_thenShowHowLongEachMethodTakes() throws CloneNotSupportedException, IOException {
int times = 1000000;
Address address = new Address("Downing St 10", "London", "England");
User pm = new User("Prime", "Minister", address);
long start = System.currentTimeMillis();
for (int i = 0; i < times; i++) {
User primeMinisterClone = (User) SerializationUtils.clone(pm);
}
long end = System.currentTimeMillis();
System.out.println("Cloning with Apache Commons Lang took " + (end - start) + " milliseconds.");
start = System.currentTimeMillis();
Gson gson = new Gson();
for (int i = 0; i < times; i++) {
User primeMinisterClone = gson.fromJson(gson.toJson(pm), User.class);
}
end = System.currentTimeMillis();
System.out.println("Cloning with Gson took " + (end - start) + " milliseconds.");
start = System.currentTimeMillis();
for (int i = 0; i < times; i++) {
User primeMinisterClone = new User(pm);
}
end = System.currentTimeMillis();
System.out.println("Cloning with the copy constructor took " + (end - start) + " milliseconds.");
start = System.currentTimeMillis();
for (int i = 0; i < times; i++) {
User primeMinisterClone = (User) pm.clone();
}
end = System.currentTimeMillis();
System.out.println("Cloning with Cloneable interface took " + (end - start) + " milliseconds.");
start = System.currentTimeMillis();
ObjectMapper objectMapper = new ObjectMapper();
for (int i = 0; i < times; i++) {
User primeMinisterClone = objectMapper.readValue(objectMapper.writeValueAsString(pm), User.class);
}
end = System.currentTimeMillis();
System.out.println("Cloning with Jackson took " + (end - start) + " milliseconds.");
}
@Test
public void whenModifyingOriginalObject_ThenCopyShouldChange() {
Address address = new Address("Downing St 10", "London", "England");
User pm = new User("Prime", "Minister", address);
User shallowCopy = new User(pm.getFirstName(), pm.getLastName(), pm.getAddress());
address.setCountry("Great Britain");
assertThat(shallowCopy.getAddress().getCountry()).isEqualTo(pm.getAddress().getCountry());
}
}

33
core-java-modules/core-java-lang-oop/src/test/java/com/baeldung/deepcopy/ShallowCopyUnitTest.java
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@@ -1,33 +0,0 @@
package com.baeldung.deepcopy;
import static org.assertj.core.api.Assertions.assertThat;
import org.junit.Test;
public class ShallowCopyUnitTest {
@Test
public void whenShallowCopying_thenObjectsShouldNotBeSame() {
Address address = new Address("Downing St 10", "London", "England");
User pm = new User("Prime", "Minister", address);
User shallowCopy = new User(pm.getFirstName(), pm.getLastName(), pm.getAddress());
assertThat(shallowCopy)
.isNotSameAs(pm);
}
@Test
public void whenModifyingOriginalObject_thenCopyShouldChange() {
Address address = new Address("Downing St 10", "London", "England");
User pm = new User("Prime", "Minister", address);
User shallowCopy = new User(pm.getFirstName(), pm.getLastName(), pm.getAddress());
address.setCountry("Great Britain");
assertThat(shallowCopy.getAddress().getCountry())
.isEqualTo(pm.getAddress().getCountry());
}
}