Override Equals method improvement (#14446)

core-java-modules/core-java-lang-oop-patterns/src/main/java/com/baeldung/deepcopyarraylist/Course.java

@@ -1,6 +1,7 @@
 package com.baeldung.deepcopyarraylist;
 
 import java.io.Serializable;
+import java.util.Objects;
 
 public class Course implements Serializable, Cloneable {
 
@@ -39,4 +40,23 @@ public class Course implements Serializable, Cloneable {
             throw new IllegalStateException(e);
         }
     }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o)
+            return true;
+
+        if (o == null || getClass() != o.getClass())
+            return false;
+
+        Course that = (Course) o;
+
+        return Objects.equals(courseId,that.courseId)
+            && Objects.equals(courseName,that.courseName);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(courseId,courseName);
+    }
 }

core-java-modules/core-java-lang-oop-patterns/src/main/java/com/baeldung/deepcopyarraylist/Student.java

@@ -2,6 +2,7 @@ package com.baeldung.deepcopyarraylist;
 
 import java.io.Serializable;
 import java.util.List;
+import java.util.Objects;
 import java.util.stream.Collectors;
 
 import org.apache.commons.lang3.SerializationUtils;
@@ -100,4 +101,23 @@ public class Student implements Serializable, Cloneable {
         student.course = this.course.clone();
         return student;
     }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o)
+            return true;
+        if (o == null || getClass() != o.getClass())
+            return false;
+
+        Student that = (Student) o;
+
+        return Objects.equals(studentId,that.studentId) &&
+            Objects.equals(studentName, that.studentName) &&
+            Objects.equals(course, that.course);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(studentId,studentName,course);
+    }
 }

core-java-modules/core-java-lang-oop-patterns/src/test/java/com/baeldung/deepcopyarraylist/DeepCopyArrayListUnitTest.java

@@ -19,8 +19,10 @@ public class DeepCopyArrayListUnitTest {
 
         List<Student> deepCopy = Student.deepCopyUsingCloneable(students);
 
-        Assertions.assertNotEquals(students.get(0), deepCopy.get(0));
+        Assertions.assertEquals(students.get(0), deepCopy.get(0));
-        Assertions.assertNotEquals(students.get(1), deepCopy.get(1));
+        Assertions.assertNotSame(students.get(0),deepCopy.get(0));
+        Assertions.assertEquals(students.get(1), deepCopy.get(1));
+        Assertions.assertNotSame(students.get(1),deepCopy.get(1));
 
     }
 
@@ -37,8 +39,10 @@ public class DeepCopyArrayListUnitTest {
 
         List<Student> deepCopy = Student.deepCopyUsingCopyConstructor(students);
 
-        Assertions.assertNotEquals(students.get(0), deepCopy.get(0));
+        Assertions.assertEquals(students.get(0), deepCopy.get(0));
-        Assertions.assertNotEquals(students.get(1), deepCopy.get(1));
+        Assertions.assertNotSame(students.get(0),deepCopy.get(0));
+        Assertions.assertEquals(students.get(1), deepCopy.get(1));
+        Assertions.assertNotSame(students.get(1),deepCopy.get(1));
     }
 
     @Test
@@ -54,8 +58,10 @@ public class DeepCopyArrayListUnitTest {
 
         List<Student> deepCopy = Student.deepCopyUsingSerialization(students);
 
-        Assertions.assertNotEquals(students.get(0), deepCopy.get(0));
+        Assertions.assertEquals(students.get(0), deepCopy.get(0));
-        Assertions.assertNotEquals(students.get(1), deepCopy.get(1));
+        Assertions.assertNotSame(students.get(0),deepCopy.get(0));
+        Assertions.assertEquals(students.get(1), deepCopy.get(1));
+        Assertions.assertNotSame(students.get(1),deepCopy.get(1));
     }
 
     @Test
@@ -71,7 +77,9 @@ public class DeepCopyArrayListUnitTest {
 
         List<Student> deepCopy = Student.deepCopyUsingJackson(students);
 
-        Assertions.assertNotEquals(students.get(0), deepCopy.get(0));
+        Assertions.assertEquals(students.get(0), deepCopy.get(0));
-        Assertions.assertNotEquals(students.get(1), deepCopy.get(1));
+        Assertions.assertNotSame(students.get(0),deepCopy.get(0));
+        Assertions.assertEquals(students.get(1), deepCopy.get(1));
+        Assertions.assertNotSame(students.get(1),deepCopy.get(1));
     }
 }