From 1d4ac342d43c9dca259e9cc349ca86968f6f99a2 Mon Sep 17 00:00:00 2001
From: Alejandro Gervasio <electricalweb@yahoo.com.ar>
Date: Thu, 20 Jul 2017 19:50:13 -0300
Subject: [PATCH 1/5] Initial Commit

---
 core-java/hashcode/pom.xml                    | 29 ++++++++++++++++
 .../com/baeldung/application/Application.java | 22 ++++++++++++
 .../main/java/com/baeldung/entities/User.java | 32 +++++++++++++++++
 .../baeldung/application/ApplicationTest.java | 30 ++++++++++++++++
 .../java/com/baeldung/entities/UserTest.java  | 34 +++++++++++++++++++
 5 files changed, 147 insertions(+)
 create mode 100644 core-java/hashcode/pom.xml
 create mode 100644 core-java/hashcode/src/main/java/com/baeldung/application/Application.java
 create mode 100644 core-java/hashcode/src/main/java/com/baeldung/entities/User.java
 create mode 100644 core-java/hashcode/src/test/java/com/baeldung/application/ApplicationTest.java
 create mode 100644 core-java/hashcode/src/test/java/com/baeldung/entities/UserTest.java

diff --git a/core-java/hashcode/pom.xml b/core-java/hashcode/pom.xml
new file mode 100644
index 000000000000..12e575443b5d
--- /dev/null
+++ b/core-java/hashcode/pom.xml
@@ -0,0 +1,29 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <groupId>com.baeldung.hashcode</groupId>
+    <artifactId>hashcode</artifactId>
+    <version>1.0</version>
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <configuration>
+                    <source>1.7</source>
+                    <target>1.7</target>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
+    <dependencies>
+        <dependency>
+            <groupId>junit</groupId>
+            <artifactId>junit</artifactId>
+            <version>4.12</version>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+</project>
\ No newline at end of file
diff --git a/core-java/hashcode/src/main/java/com/baeldung/application/Application.java b/core-java/hashcode/src/main/java/com/baeldung/application/Application.java
new file mode 100644
index 000000000000..13d97fec5770
--- /dev/null
+++ b/core-java/hashcode/src/main/java/com/baeldung/application/Application.java
@@ -0,0 +1,22 @@
+package com.baeldung.application;
+
+import com.baeldung.entities.User;
+import java.util.*;
+
+public class Application {
+
+    public static void main(String[] args) {
+        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);
+
+        if (users.containsKey(user1)) {
+            System.out.print("User found in the collection");
+        }
+    }
+}
diff --git a/core-java/hashcode/src/main/java/com/baeldung/entities/User.java b/core-java/hashcode/src/main/java/com/baeldung/entities/User.java
new file mode 100644
index 000000000000..ae41de0cfcea
--- /dev/null
+++ b/core-java/hashcode/src/main/java/com/baeldung/entities/User.java
@@ -0,0 +1,32 @@
+package com.baeldung.entities;
+
+public class User {
+
+    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));
+    }
+
+    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());
+        return hash;
+    }
+    // getters and setters here
+}
diff --git a/core-java/hashcode/src/test/java/com/baeldung/application/ApplicationTest.java b/core-java/hashcode/src/test/java/com/baeldung/application/ApplicationTest.java
new file mode 100644
index 000000000000..dcd853f451d9
--- /dev/null
+++ b/core-java/hashcode/src/test/java/com/baeldung/application/ApplicationTest.java
@@ -0,0 +1,30 @@
+package com.baeldung.application;
+
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+import java.io.ByteArrayOutputStream;
+import java.io.PrintStream;
+import static org.junit.Assert.assertEquals;
+
+public class ApplicationTest {
+
+    private ByteArrayOutputStream outContent;
+
+    @Before
+    public void setUpPrintStreamInstance() throws Exception {
+        this.outContent = new ByteArrayOutputStream();
+        System.setOut(new PrintStream(outContent));
+    }
+
+    @After
+    public void tearDownByteArrayOutputStream() throws Exception {
+        outContent = null;
+    }
+
+    @Test
+    public void main_NoInputState_TextPrintedToConsole() throws Exception {
+        Application.main(new String[]{});
+        assertEquals("User found in the collection", outContent.toString());
+    }
+}
\ No newline at end of file
diff --git a/core-java/hashcode/src/test/java/com/baeldung/entities/UserTest.java b/core-java/hashcode/src/test/java/com/baeldung/entities/UserTest.java
new file mode 100644
index 000000000000..01f6085d7eac
--- /dev/null
+++ b/core-java/hashcode/src/test/java/com/baeldung/entities/UserTest.java
@@ -0,0 +1,34 @@
+package com.baeldung.entities;
+
+import org.junit.After;
+import org.junit.Assert;
+import org.junit.Before;
+import org.junit.Test;
+
+public class UserTest {
+
+    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());
+    }
+}
\ No newline at end of file

From 6600ac9b69d1fdef81f6d8ec9ccd0c6da5acf9f5 Mon Sep 17 00:00:00 2001
From: Alejandro Gervasio <electricalweb@yahoo.com.ar>
Date: Thu, 20 Jul 2017 19:57:42 -0300
Subject: [PATCH 2/5] Updated pom.xml

---
 core-java/hashcode/pom.xml | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/core-java/hashcode/pom.xml b/core-java/hashcode/pom.xml
index 12e575443b5d..b3d010546613 100644
--- a/core-java/hashcode/pom.xml
+++ b/core-java/hashcode/pom.xml
@@ -12,8 +12,8 @@
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-compiler-plugin</artifactId>
                 <configuration>
-                    <source>1.7</source>
-                    <target>1.7</target>
+                    <source>1.8</source>
+                    <target>1.8</target>
                 </configuration>
             </plugin>
         </plugins>

From 827819751422820353b18039754a4080db68342e Mon Sep 17 00:00:00 2001
From: Alejandro Gervasio <electricalweb@yahoo.com.ar>
Date: Thu, 20 Jul 2017 21:09:05 -0300
Subject: [PATCH 3/5] Updated User class

---
 .../hashcode/src/main/java/com/baeldung/entities/User.java     | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/core-java/hashcode/src/main/java/com/baeldung/entities/User.java b/core-java/hashcode/src/main/java/com/baeldung/entities/User.java
index ae41de0cfcea..a426b21e7a95 100644
--- a/core-java/hashcode/src/main/java/com/baeldung/entities/User.java
+++ b/core-java/hashcode/src/main/java/com/baeldung/entities/User.java
@@ -20,7 +20,8 @@ public boolean equals(Object o) {
         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;

From 2a3acf3cc89d5d1fe0edd5f3d6fe391c50bc64c4 Mon Sep 17 00:00:00 2001
From: Alejandro Gervasio <electricalweb@yahoo.com.ar>
Date: Mon, 24 Jul 2017 15:41:56 -0300
Subject: [PATCH 4/5] Updated pom.xml

---
 core-java/hashcode/pom.xml                             | 10 ++++++++++
 .../src/main/java/com/baeldung/entities/User.java      |  7 ++++++-
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/core-java/hashcode/pom.xml b/core-java/hashcode/pom.xml
index b3d010546613..393aa69153e9 100644
--- a/core-java/hashcode/pom.xml
+++ b/core-java/hashcode/pom.xml
@@ -25,5 +25,15 @@
             <version>4.12</version>
             <scope>test</scope>
         </dependency>
+        <dependency>
+            <groupId>org.slf4j</groupId>
+            <artifactId>slf4j-api</artifactId>
+            <version>1.7.25</version>
+        </dependency>
+        <dependency>
+            <groupId>org.slf4j</groupId>
+            <artifactId>slf4j-simple</artifactId>
+            <version>1.7.25</version>
+        </dependency>
     </dependencies>
 </project>
\ No newline at end of file
diff --git a/core-java/hashcode/src/main/java/com/baeldung/entities/User.java b/core-java/hashcode/src/main/java/com/baeldung/entities/User.java
index a426b21e7a95..a976233562dc 100644
--- a/core-java/hashcode/src/main/java/com/baeldung/entities/User.java
+++ b/core-java/hashcode/src/main/java/com/baeldung/entities/User.java
@@ -1,7 +1,11 @@
 package com.baeldung.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;
@@ -20,13 +24,14 @@ public boolean equals(Object o) {
         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

From ff284c697101387c33499fed05a4b858cc8f3511 Mon Sep 17 00:00:00 2001
From: Alejandro Gervasio <electricalweb@yahoo.com.ar>
Date: Mon, 24 Jul 2017 17:51:58 -0300
Subject: [PATCH 5/5] Updated Application class

---
 .../src/main/java/com/baeldung/application/Application.java    | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/core-java/hashcode/src/main/java/com/baeldung/application/Application.java b/core-java/hashcode/src/main/java/com/baeldung/application/Application.java
index 13d97fec5770..08c670c82f78 100644
--- a/core-java/hashcode/src/main/java/com/baeldung/application/Application.java
+++ b/core-java/hashcode/src/main/java/com/baeldung/application/Application.java
@@ -1,7 +1,8 @@
 package com.baeldung.application;
 
 import com.baeldung.entities.User;
-import java.util.*;
+import java.util.HashMap;
+import java.util.Map;
 
 public class Application {