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

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* Creation

* Moved code from https://www.baeldung.com/java-equals-hashcode-contracts

* Moved code from www.baeldung.com/java-hashcode

* Moved code from https://www.baeldung.com/java-method-overload-override

* Moved code from www.baeldung.com/java-methods

* Moved article references to the new README.md
This commit is contained in:
dupirefr
2020-04-04 11:38:22 +02:00
parent 21a98198b6
commit 867d63a9d5
23 changed files with 45 additions and 4 deletions
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2
core-java-modules/core-java-lang-oop/README.md
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@@ -3,8 +3,6 @@
This module contains articles about Object-oriented programming (OOP) in Java
### Relevant Articles:
- [Guide to hashCode() in Java](https://www.baeldung.com/java-hashcode)
- [Method Overloading and Overriding in Java](https://www.baeldung.com/java-method-overload-override)
- [How to Make a Deep Copy of an Object in Java](https://www.baeldung.com/java-deep-copy)
- [Type Erasure in Java Explained](https://www.baeldung.com/java-type-erasure)
- [Object-Oriented-Programming Concepts in Java](https://www.baeldung.com/java-oop)

42
core-java-modules/core-java-lang-oop/src/main/java/com/baeldung/hashcode/entities/User.java
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package com.baeldung.hashcode.entities;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
public class User {
private final Logger logger = LoggerFactory.getLogger(User.class);
private long id;
private String name;
private String email;
public User(long id, String name, String email) {
this.id = id;
this.name = name;
this.email = email;
}
@Override
public boolean equals(Object o) {
if (this == o)
return true;
if (o == null)
return false;
if (this.getClass() != o.getClass())
return false;
User user = (User) o;
return id == user.id && (name.equals(user.name) && email.equals(user.email));
}
@Override
public int hashCode() {
int hash = 7;
hash = 31 * hash + (int) id;
hash = 31 * hash + (name == null ? 0 : name.hashCode());
hash = 31 * hash + (email == null ? 0 : email.hashCode());
logger.info("hashCode() method called - Computed hash: " + hash);
return hash;
}
// getters and setters here
}

26
core-java-modules/core-java-lang-oop/src/main/java/com/baeldung/methodoverloadingoverriding/application/Application.java
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@@ -1,26 +0,0 @@
package com.baeldung.methodoverloadingoverriding.application;
import com.baeldung.methodoverloadingoverriding.model.Car;
import com.baeldung.methodoverloadingoverriding.model.Vehicle;
import com.baeldung.methodoverloadingoverriding.util.Multiplier;
public class Application {
public static void main(String[] args) {
Multiplier multiplier = new Multiplier();
System.out.println(multiplier.multiply(10, 10));
System.out.println(multiplier.multiply(10, 10, 10));
System.out.println(multiplier.multiply(10, 10.5));
System.out.println(multiplier.multiply(10.5, 10.5));
Vehicle vehicle = new Vehicle();
System.out.println(vehicle.accelerate(100));
System.out.println(vehicle.run());
System.out.println(vehicle.stop());
Vehicle car = new Car();
System.out.println(car.accelerate(80));
System.out.println(car.run());
System.out.println(car.stop());
}
}

9
core-java-modules/core-java-lang-oop/src/main/java/com/baeldung/methodoverloadingoverriding/model/Car.java
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@@ -1,9 +0,0 @@
package com.baeldung.methodoverloadingoverriding.model;
public class Car extends Vehicle {
@Override
public String accelerate(long mph) {
return "The car accelerates at : " + mph + " MPH.";
}
}

16
core-java-modules/core-java-lang-oop/src/main/java/com/baeldung/methodoverloadingoverriding/model/Vehicle.java
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@@ -1,16 +0,0 @@
package com.baeldung.methodoverloadingoverriding.model;
public class Vehicle {
public String accelerate(long mph) {
return "The vehicle accelerates at : " + mph + " MPH.";
}
public String stop() {
return "The vehicle has stopped.";
}
public String run() {
return "The vehicle is running.";
}
}

16
core-java-modules/core-java-lang-oop/src/main/java/com/baeldung/methodoverloadingoverriding/util/Multiplier.java
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@@ -1,16 +0,0 @@
package com.baeldung.methodoverloadingoverriding.util;
public class Multiplier {
public int multiply(int a, int b) {
return a * b;
}
public int multiply(int a, int b, int c) {
return a * b * c;
}
public double multiply(double a, double b) {
return a * b;
}
}

26
core-java-modules/core-java-lang-oop/src/test/java/com/baeldung/hashcode/application/ApplicationUnitTest.java
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@@ -1,26 +0,0 @@
package com.baeldung.hashcode.application;
import com.baeldung.hashcode.entities.User;
import org.junit.Test;
import java.util.HashMap;
import java.util.Map;
import static org.junit.Assert.assertTrue;
public class ApplicationUnitTest {
@Test
public void main_NoInputState_TextPrintedToConsole() throws Exception {
Map<User, User> users = new HashMap<>();
User user1 = new User(1L, "John", "john@domain.com");
User user2 = new User(2L, "Jennifer", "jennifer@domain.com");
User user3 = new User(3L, "Mary", "mary@domain.com");
users.put(user1, user1);
users.put(user2, user2);
users.put(user3, user3);
assertTrue(users.containsKey(user1));
}
}

34
core-java-modules/core-java-lang-oop/src/test/java/com/baeldung/hashcode/entities/UserUnitTest.java
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@@ -1,34 +0,0 @@
package com.baeldung.hashcode.entities;
import org.junit.After;
import org.junit.Assert;
import org.junit.Before;
import org.junit.Test;
public class UserUnitTest {
private User user;
private User comparisonUser;
@Before
public void setUpUserInstances() {
this.user = new User(1L, "test", "test@domain.com");
this.comparisonUser = this.user;
}
@After
public void tearDownUserInstances() {
user = null;
comparisonUser = null;
}
@Test
public void equals_EqualUserInstance_TrueAssertion() {
Assert.assertTrue(user.equals(comparisonUser));
}
@Test
public void hashCode_UserHash_TrueAssertion() {
Assert.assertEquals(1792276941, user.hashCode());
}
}

41
core-java-modules/core-java-lang-oop/src/test/java/com/baeldung/methodoverloadingoverriding/test/MethodOverloadingUnitTest.java
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@@ -1,41 +0,0 @@
package com.baeldung.methodoverloadingoverriding.test;
import com.baeldung.methodoverloadingoverriding.util.Multiplier;
import org.junit.BeforeClass;
import org.junit.Test;
import static org.assertj.core.api.Assertions.*;
public class MethodOverloadingUnitTest {
private static Multiplier multiplier;
@BeforeClass
public static void setUpMultiplierInstance() {
multiplier = new Multiplier();
}
@Test
public void givenMultiplierInstance_whenCalledMultiplyWithTwoIntegers_thenOneAssertion() {
assertThat(multiplier.multiply(10, 10)).isEqualTo(100);
}
@Test
public void givenMultiplierInstance_whenCalledMultiplyWithTreeIntegers_thenOneAssertion() {
assertThat(multiplier.multiply(10, 10, 10)).isEqualTo(1000);
}
@Test
public void givenMultiplierInstance_whenCalledMultiplyWithIntDouble_thenOneAssertion() {
assertThat(multiplier.multiply(10, 10.5)).isEqualTo(105.0);
}
@Test
public void givenMultiplierInstance_whenCalledMultiplyWithDoubleDouble_thenOneAssertion() {
assertThat(multiplier.multiply(10.5, 10.5)).isEqualTo(110.25);
}
@Test
public void givenMultiplierInstance_whenCalledMultiplyWithIntIntAndMatching_thenNoTypePromotion() {
assertThat(multiplier.multiply(10, 10)).isEqualTo(100);
}
}

68
core-java-modules/core-java-lang-oop/src/test/java/com/baeldung/methodoverloadingoverriding/test/MethodOverridingUnitTest.java
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@@ -1,68 +0,0 @@
package com.baeldung.methodoverloadingoverriding.test;
import com.baeldung.methodoverloadingoverriding.model.Car;
import com.baeldung.methodoverloadingoverriding.model.Vehicle;
import org.junit.BeforeClass;
import org.junit.Test;
import static org.assertj.core.api.Assertions.*;
public class MethodOverridingUnitTest {
private static Vehicle vehicle;
private static Car car;
@BeforeClass
public static void setUpVehicleInstance() {
vehicle = new Vehicle();
}
@BeforeClass
public static void setUpCarInstance() {
car = new Car();
}
@Test
public void givenVehicleInstance_whenCalledAccelerate_thenOneAssertion() {
assertThat(vehicle.accelerate(100)).isEqualTo("The vehicle accelerates at : 100 MPH.");
}
@Test
public void givenVehicleInstance_whenCalledRun_thenOneAssertion() {
assertThat(vehicle.run()).isEqualTo("The vehicle is running.");
}
@Test
public void givenVehicleInstance_whenCalledStop_thenOneAssertion() {
assertThat(vehicle.stop()).isEqualTo("The vehicle has stopped.");
}
@Test
public void givenCarInstance_whenCalledAccelerate_thenOneAssertion() {
assertThat(car.accelerate(80)).isEqualTo("The car accelerates at : 80 MPH.");
}
@Test
public void givenCarInstance_whenCalledRun_thenOneAssertion() {
assertThat(car.run()).isEqualTo("The vehicle is running.");
}
@Test
public void givenCarInstance_whenCalledStop_thenOneAssertion() {
assertThat(car.stop()).isEqualTo("The vehicle has stopped.");
}
@Test
public void givenVehicleCarInstances_whenCalledAccelerateWithSameArgument_thenNotEqual() {
assertThat(vehicle.accelerate(100)).isNotEqualTo(car.accelerate(100));
}
@Test
public void givenVehicleCarInstances_whenCalledRun_thenEqual() {
assertThat(vehicle.run()).isEqualTo(car.run());
}
@Test
public void givenVehicleCarInstances_whenCalledStop_thenEqual() {
assertThat(vehicle.stop()).isEqualTo(car.stop());
}
}