refactoring: unit of work (#1940)

Co-authored-by: Subhrodip Mohanta <hello@subho.xyz>

unit-of-work/src/main/java/com/iluwatar/unitofwork/App.java

@@ -27,7 +27,7 @@ import java.util.HashMap;
 import java.util.List;
 
 /**
- * {@link App} Application for managing student data.
+ * {@link App} Application demonstrating unit of work pattern.
  */
 public class App {
   /**
@@ -37,17 +37,19 @@ public class App {
    */
 
   public static void main(String[] args) {
-    var ram = new Student(1, "Ram", "Street 9, Cupertino");
-    var shyam = new Student(2, "Shyam", "Z bridge, Pune");
-    var gopi = new Student(3, "Gopi", "Street 10, Mumbai");
+    // create some weapons
+    var enchantedHammer = new Weapon(1, "enchanted hammer");
+    var brokenGreatSword = new Weapon(2, "broken great sword");
+    var silverTrident = new Weapon(3, "silver trident");
 
-    var context = new HashMap<String, List<Student>>();
-    var studentDatabase = new StudentDatabase();
-    var studentRepository = new StudentRepository(context, studentDatabase);
+    // create repository
+    var weaponRepository = new ArmsDealer(new HashMap<String, List<Weapon>>(),
+            new WeaponDatabase());
 
-    studentRepository.registerNew(ram);
-    studentRepository.registerModified(shyam);
-    studentRepository.registerDeleted(gopi);
-    studentRepository.commit();
+    // perform operations on the weapons
+    weaponRepository.registerNew(enchantedHammer);
+    weaponRepository.registerModified(silverTrident);
+    weaponRepository.registerDeleted(brokenGreatSword);
+    weaponRepository.commit();
   }
 }

unit-of-work/src/main/java/com/iluwatar/unitofwork/ArmsDealer.java

@@ -30,41 +30,41 @@ import lombok.RequiredArgsConstructor;
 import lombok.extern.slf4j.Slf4j;
 
 /**
- * {@link StudentRepository} Student database repository. supports unit of work for student data.
+ * {@link ArmsDealer} Weapon repository that supports unit of work for weapons.
  */
 @Slf4j
 @RequiredArgsConstructor
-public class StudentRepository implements IUnitOfWork<Student> {
+public class ArmsDealer implements IUnitOfWork<Weapon> {
 
-  private final Map<String, List<Student>> context;
-  private final StudentDatabase studentDatabase;
+  private final Map<String, List<Weapon>> context;
+  private final WeaponDatabase weaponDatabase;
 
   @Override
-  public void registerNew(Student student) {
-    LOGGER.info("Registering {} for insert in context.", student.getName());
-    register(student, UnitActions.INSERT.getActionValue());
+  public void registerNew(Weapon weapon) {
+    LOGGER.info("Registering {} for insert in context.", weapon.getName());
+    register(weapon, UnitActions.INSERT.getActionValue());
   }
 
   @Override
-  public void registerModified(Student student) {
-    LOGGER.info("Registering {} for modify in context.", student.getName());
-    register(student, UnitActions.MODIFY.getActionValue());
+  public void registerModified(Weapon weapon) {
+    LOGGER.info("Registering {} for modify in context.", weapon.getName());
+    register(weapon, UnitActions.MODIFY.getActionValue());
 
   }
 
   @Override
-  public void registerDeleted(Student student) {
-    LOGGER.info("Registering {} for delete in context.", student.getName());
-    register(student, UnitActions.DELETE.getActionValue());
+  public void registerDeleted(Weapon weapon) {
+    LOGGER.info("Registering {} for delete in context.", weapon.getName());
+    register(weapon, UnitActions.DELETE.getActionValue());
   }
 
-  private void register(Student student, String operation) {
-    var studentsToOperate = context.get(operation);
-    if (studentsToOperate == null) {
-      studentsToOperate = new ArrayList<>();
+  private void register(Weapon weapon, String operation) {
+    var weaponsToOperate = context.get(operation);
+    if (weaponsToOperate == null) {
+      weaponsToOperate = new ArrayList<>();
     }
-    studentsToOperate.add(student);
-    context.put(operation, studentsToOperate);
+    weaponsToOperate.add(weapon);
+    context.put(operation, weaponsToOperate);
   }
 
   /**
@@ -90,26 +90,26 @@ public class StudentRepository implements IUnitOfWork<Student> {
   }
 
   private void commitInsert() {
-    var studentsToBeInserted = context.get(UnitActions.INSERT.getActionValue());
-    for (var student : studentsToBeInserted) {
-      LOGGER.info("Saving {} to database.", student.getName());
-      studentDatabase.insert(student);
+    var weaponsToBeInserted = context.get(UnitActions.INSERT.getActionValue());
+    for (var weapon : weaponsToBeInserted) {
+      LOGGER.info("Inserting a new weapon {} to sales rack.", weapon.getName());
+      weaponDatabase.insert(weapon);
     }
   }
 
   private void commitModify() {
-    var modifiedStudents = context.get(UnitActions.MODIFY.getActionValue());
-    for (var student : modifiedStudents) {
-      LOGGER.info("Modifying {} to database.", student.getName());
-      studentDatabase.modify(student);
+    var modifiedWeapons = context.get(UnitActions.MODIFY.getActionValue());
+    for (var weapon : modifiedWeapons) {
+      LOGGER.info("Scheduling {} for modification work.", weapon.getName());
+      weaponDatabase.modify(weapon);
     }
   }
 
   private void commitDelete() {
-    var deletedStudents = context.get(UnitActions.DELETE.getActionValue());
-    for (var student : deletedStudents) {
-      LOGGER.info("Deleting {} to database.", student.getName());
-      studentDatabase.delete(student);
+    var deletedWeapons = context.get(UnitActions.DELETE.getActionValue());
+    for (var weapon : deletedWeapons) {
+      LOGGER.info("Scrapping {}.", weapon.getName());
+      weaponDatabase.delete(weapon);
     }
   }
 }

unit-of-work/src/main/java/com/iluwatar/unitofwork/Weapon.java

@@ -27,14 +27,12 @@ import lombok.Getter;
 import lombok.RequiredArgsConstructor;
 
 /**
- * {@link Student} is an entity.
+ * {@link Weapon} is an entity.
  */
 @Getter
 @RequiredArgsConstructor
-public class Student {
+public class Weapon {
 
   private final Integer id;
   private final String name;
-  private final String address;
-
 }

unit-of-work/src/main/java/com/iluwatar/unitofwork/WeaponDatabase.java

@@ -24,19 +24,19 @@
 package com.iluwatar.unitofwork;
 
 /**
- * Act as Database for student records.
+ * Act as database for weapon records.
  */
-public class StudentDatabase {
+public class WeaponDatabase {
 
-  public void insert(Student student) {
+  public void insert(Weapon weapon) {
     //Some insert logic to DB
   }
 
-  public void modify(Student student) {
+  public void modify(Weapon weapon) {
     //Some modify logic to DB
   }
 
-  public void delete(Student student) {
+  public void delete(Weapon weapon) {
     //Some delete logic to DB
   }
 }