Java 11 support for #984 #987 (l) (#1190)

* Java 11 support: lazy-loading pattern

* Java 11 support: layers pattern

* Java 11 support: leader-election/lazy-loading patterns

layers/src/main/java/com/iluwatar/layers/app/App.java

@@ -93,7 +93,7 @@ public class App {
     initializeData(cakeBakingService);
 
     // create view and render it
-    CakeViewImpl cakeView = new CakeViewImpl(cakeBakingService);
+    var cakeView = new CakeViewImpl(cakeBakingService);
     cakeView.render();
   }
 
@@ -111,17 +111,16 @@ public class App {
     cakeBakingService.saveNewTopping(new CakeToppingInfo("candies", 350));
     cakeBakingService.saveNewTopping(new CakeToppingInfo("cherry", 350));
 
-    CakeInfo cake1 =
+    var cake1 = new CakeInfo(new CakeToppingInfo("candies", 0), List.of(
-            new CakeInfo(new CakeToppingInfo("candies", 0), List.of(
+        new CakeLayerInfo("chocolate", 0),
-                    new CakeLayerInfo("chocolate", 0),
+        new CakeLayerInfo("banana", 0),
-                    new CakeLayerInfo("banana", 0),
+        new CakeLayerInfo("strawberry", 0)));
-                    new CakeLayerInfo("strawberry", 0)));
     try {
       cakeBakingService.bakeNewCake(cake1);
     } catch (CakeBakingException e) {
       e.printStackTrace();
     }
-    CakeInfo cake2 = new CakeInfo(new CakeToppingInfo("cherry", 0), List.of(
+    var cake2 = new CakeInfo(new CakeToppingInfo("cherry", 0), List.of(
         new CakeLayerInfo("vanilla", 0),
         new CakeLayerInfo("lemon", 0),
         new CakeLayerInfo("strawberry", 0)));

layers/src/main/java/com/iluwatar/layers/dto/CakeInfo.java

@@ -57,7 +57,7 @@ public class CakeInfo {
    * Calculate calories.
    */
   public int calculateTotalCalories() {
-    int total = cakeToppingInfo != null ? cakeToppingInfo.calories : 0;
+    var total = cakeToppingInfo != null ? cakeToppingInfo.calories : 0;
     total += cakeLayerInfos.stream().mapToInt(c -> c.calories).sum();
     return total;
   }

layers/src/main/java/com/iluwatar/layers/service/CakeBakingServiceImpl.java

@@ -60,65 +60,63 @@ public class CakeBakingServiceImpl implements CakeBakingService {
 
   @Override
   public void bakeNewCake(CakeInfo cakeInfo) throws CakeBakingException {
-    List<CakeTopping> allToppings = getAvailableToppingEntities();
+    var allToppings = getAvailableToppingEntities();
-    List<CakeTopping> matchingToppings =
+    var matchingToppings =
         allToppings.stream().filter(t -> t.getName().equals(cakeInfo.cakeToppingInfo.name))
             .collect(Collectors.toList());
     if (matchingToppings.isEmpty()) {
       throw new CakeBakingException(String.format("Topping %s is not available",
           cakeInfo.cakeToppingInfo.name));
     }
-    List<CakeLayer> allLayers = getAvailableLayerEntities();
+    var allLayers = getAvailableLayerEntities();
     Set<CakeLayer> foundLayers = new HashSet<>();
-    for (CakeLayerInfo info : cakeInfo.cakeLayerInfos) {
+    for (var info : cakeInfo.cakeLayerInfos) {
-      Optional<CakeLayer> found =
+      var found = allLayers.stream().filter(layer -> layer.getName().equals(info.name)).findFirst();
-          allLayers.stream().filter(layer -> layer.getName().equals(info.name)).findFirst();
       if (!found.isPresent()) {
         throw new CakeBakingException(String.format("Layer %s is not available", info.name));
       } else {
         foundLayers.add(found.get());
       }
     }
-    CakeToppingDao toppingBean = context.getBean(CakeToppingDao.class);
+    var toppingBean = context.getBean(CakeToppingDao.class);
-    Optional<CakeTopping> topping = toppingBean.findById(
+    var topping = toppingBean.findById(matchingToppings.iterator().next().getId());
-        matchingToppings.iterator().next().getId());
+    var cakeBean = context.getBean(CakeDao.class);
-    CakeDao cakeBean = context.getBean(CakeDao.class);
     if (topping.isPresent()) {
-      Cake cake = new Cake();
+      var cake = new Cake();
       cake.setTopping(topping.get());
       cake.setLayers(foundLayers);
       cakeBean.save(cake);
       topping.get().setCake(cake);
       toppingBean.save(topping.get());
-      CakeLayerDao layerBean = context.getBean(CakeLayerDao.class);
+      var layerBean = context.getBean(CakeLayerDao.class);
-      for (CakeLayer layer : foundLayers) {
+      for (var layer : foundLayers) {
         layer.setCake(cake);
         layerBean.save(layer);
       }
     } else {
       throw new CakeBakingException(String.format("Topping %s is not available",
-              cakeInfo.cakeToppingInfo.name));
+          cakeInfo.cakeToppingInfo.name));
     }
   }
 
   @Override
   public void saveNewTopping(CakeToppingInfo toppingInfo) {
-    CakeToppingDao bean = context.getBean(CakeToppingDao.class);
+    var bean = context.getBean(CakeToppingDao.class);
     bean.save(new CakeTopping(toppingInfo.name, toppingInfo.calories));
   }
 
   @Override
   public void saveNewLayer(CakeLayerInfo layerInfo) {
-    CakeLayerDao bean = context.getBean(CakeLayerDao.class);
+    var bean = context.getBean(CakeLayerDao.class);
     bean.save(new CakeLayer(layerInfo.name, layerInfo.calories));
   }
 
   private List<CakeTopping> getAvailableToppingEntities() {
-    CakeToppingDao bean = context.getBean(CakeToppingDao.class);
+    var bean = context.getBean(CakeToppingDao.class);
     List<CakeTopping> result = new ArrayList<>();
-    Iterator<CakeTopping> iterator = bean.findAll().iterator();
+    var iterator = bean.findAll().iterator();
     while (iterator.hasNext()) {
-      CakeTopping topping = iterator.next();
+      var topping = iterator.next();
       if (topping.getCake() == null) {
         result.add(topping);
       }
@@ -128,11 +126,11 @@ public class CakeBakingServiceImpl implements CakeBakingService {
 
   @Override
   public List<CakeToppingInfo> getAvailableToppings() {
-    CakeToppingDao bean = context.getBean(CakeToppingDao.class);
+    var bean = context.getBean(CakeToppingDao.class);
     List<CakeToppingInfo> result = new ArrayList<>();
-    Iterator<CakeTopping> iterator = bean.findAll().iterator();
+    var iterator = bean.findAll().iterator();
     while (iterator.hasNext()) {
-      CakeTopping next = iterator.next();
+      var next = iterator.next();
       if (next.getCake() == null) {
         result.add(new CakeToppingInfo(next.getId(), next.getName(), next.getCalories()));
       }
@@ -141,11 +139,11 @@ public class CakeBakingServiceImpl implements CakeBakingService {
   }
 
   private List<CakeLayer> getAvailableLayerEntities() {
-    CakeLayerDao bean = context.getBean(CakeLayerDao.class);
+    var bean = context.getBean(CakeLayerDao.class);
     List<CakeLayer> result = new ArrayList<>();
-    Iterator<CakeLayer> iterator = bean.findAll().iterator();
+    var iterator = bean.findAll().iterator();
     while (iterator.hasNext()) {
-      CakeLayer next = iterator.next();
+      var next = iterator.next();
       if (next.getCake() == null) {
         result.add(next);
       }
@@ -155,11 +153,11 @@ public class CakeBakingServiceImpl implements CakeBakingService {
 
   @Override
   public List<CakeLayerInfo> getAvailableLayers() {
-    CakeLayerDao bean = context.getBean(CakeLayerDao.class);
+    var bean = context.getBean(CakeLayerDao.class);
     List<CakeLayerInfo> result = new ArrayList<>();
-    Iterator<CakeLayer> iterator = bean.findAll().iterator();
+    var iterator = bean.findAll().iterator();
     while (iterator.hasNext()) {
-      CakeLayer next = iterator.next();
+      var next = iterator.next();
       if (next.getCake() == null) {
         result.add(new CakeLayerInfo(next.getId(), next.getName(), next.getCalories()));
       }
@@ -169,19 +167,19 @@ public class CakeBakingServiceImpl implements CakeBakingService {
 
   @Override
   public List<CakeInfo> getAllCakes() {
-    CakeDao cakeBean = context.getBean(CakeDao.class);
+    var cakeBean = context.getBean(CakeDao.class);
     List<CakeInfo> result = new ArrayList<>();
-    Iterator<Cake> iterator = cakeBean.findAll().iterator();
+    var iterator = cakeBean.findAll().iterator();
     while (iterator.hasNext()) {
-      Cake cake = iterator.next();
+      var cake = iterator.next();
-      CakeToppingInfo cakeToppingInfo =
+      var cakeToppingInfo =
           new CakeToppingInfo(cake.getTopping().getId(), cake.getTopping().getName(), cake
               .getTopping().getCalories());
       List<CakeLayerInfo> cakeLayerInfos = new ArrayList<>();
-      for (CakeLayer layer : cake.getLayers()) {
+      for (var layer : cake.getLayers()) {
         cakeLayerInfos.add(new CakeLayerInfo(layer.getId(), layer.getName(), layer.getCalories()));
       }
-      CakeInfo cakeInfo = new CakeInfo(cake.getId(), cakeToppingInfo, cakeLayerInfos);
+      var cakeInfo = new CakeInfo(cake.getId(), cakeToppingInfo, cakeLayerInfos);
       result.add(cakeInfo);
     }
     return result;

layers/src/test/java/com/iluwatar/layers/entity/CakeTest.java

@@ -45,31 +45,31 @@ public class CakeTest {
 
   @Test
   public void testSetId() {
-    final Cake cake = new Cake();
+    final var cake = new Cake();
     assertNull(cake.getId());
 
-    final Long expectedId = 1234L;
+    final var expectedId = 1234L;
     cake.setId(expectedId);
     assertEquals(expectedId, cake.getId());
   }
 
   @Test
   public void testSetTopping() {
-    final Cake cake = new Cake();
+    final var cake = new Cake();
     assertNull(cake.getTopping());
 
-    final CakeTopping expectedTopping = new CakeTopping("DummyTopping", 1000);
+    final var expectedTopping = new CakeTopping("DummyTopping", 1000);
     cake.setTopping(expectedTopping);
     assertEquals(expectedTopping, cake.getTopping());
   }
 
   @Test
   public void testSetLayers() {
-    final Cake cake = new Cake();
+    final var cake = new Cake();
     assertNotNull(cake.getLayers());
     assertTrue(cake.getLayers().isEmpty());
 
-    final Set<CakeLayer> expectedLayers = Set.of(
+    final var expectedLayers = Set.of(
             new CakeLayer("layer1", 1000),
             new CakeLayer("layer2", 2000),
             new CakeLayer("layer3", 3000));
@@ -79,7 +79,7 @@ public class CakeTest {
 
   @Test
   public void testAddLayer() {
-    final Cake cake = new Cake();
+    final var cake = new Cake();
     assertNotNull(cake.getLayers());
     assertTrue(cake.getLayers().isEmpty());
 
@@ -90,7 +90,7 @@ public class CakeTest {
     cake.setLayers(initialLayers);
     assertEquals(initialLayers, cake.getLayers());
 
-    final CakeLayer newLayer = new CakeLayer("layer3", 3000);
+    final var newLayer = new CakeLayer("layer3", 3000);
     cake.addLayer(newLayer);
 
     final Set<CakeLayer> expectedLayers = new HashSet<>();
@@ -102,18 +102,18 @@ public class CakeTest {
 
   @Test
   public void testToString() {
-    final CakeTopping topping = new CakeTopping("topping", 20);
+    final var topping = new CakeTopping("topping", 20);
     topping.setId(2345L);
 
-    final CakeLayer layer = new CakeLayer("layer", 100);
+    final var layer = new CakeLayer("layer", 100);
     layer.setId(3456L);
 
-    final Cake cake = new Cake();
+    final var cake = new Cake();
     cake.setId(1234L);
     cake.setTopping(topping);
     cake.addLayer(layer);
 
-    final String expected = "id=1234 topping=id=2345 name=topping calories=20 "
+    final var expected = "id=1234 topping=id=2345 name=topping calories=20 "
             + "layers=[id=3456 name=layer calories=100]";
     assertEquals(expected, cake.toString());
 

layers/src/test/java/com/iluwatar/layers/exception/CakeBakingExceptionTest.java

@@ -38,15 +38,15 @@ public class CakeBakingExceptionTest {
 
   @Test
   public void testConstructor() {
-    final CakeBakingException exception = new CakeBakingException();
+    final var exception = new CakeBakingException();
     assertNull(exception.getMessage());
     assertNull(exception.getCause());
   }
 
   @Test
   public void testConstructorWithMessage() {
-    final String expectedMessage = "message";
+    final var expectedMessage = "message";
-    final CakeBakingException exception = new CakeBakingException(expectedMessage);
+    final var exception = new CakeBakingException(expectedMessage);
     assertEquals(expectedMessage, exception.getMessage());
     assertNull(exception.getCause());
   }

layers/src/test/java/com/iluwatar/layers/service/CakeBakingServiceImplTest.java

@@ -44,19 +44,19 @@ public class CakeBakingServiceImplTest {
 
   @Test
   public void testLayers() {
-    final CakeBakingServiceImpl service = new CakeBakingServiceImpl();
+    final var service = new CakeBakingServiceImpl();
 
-    final List<CakeLayerInfo> initialLayers = service.getAvailableLayers();
+    final var initialLayers = service.getAvailableLayers();
     assertNotNull(initialLayers);
     assertTrue(initialLayers.isEmpty());
 
     service.saveNewLayer(new CakeLayerInfo("Layer1", 1000));
     service.saveNewLayer(new CakeLayerInfo("Layer2", 2000));
 
-    final List<CakeLayerInfo> availableLayers = service.getAvailableLayers();
+    final var availableLayers = service.getAvailableLayers();
     assertNotNull(availableLayers);
     assertEquals(2, availableLayers.size());
-    for (final CakeLayerInfo layer : availableLayers) {
+    for (final var layer : availableLayers) {
       assertNotNull(layer.id);
       assertNotNull(layer.name);
       assertNotNull(layer.toString());
@@ -67,19 +67,19 @@ public class CakeBakingServiceImplTest {
 
   @Test
   public void testToppings() {
-    final CakeBakingServiceImpl service = new CakeBakingServiceImpl();
+    final var service = new CakeBakingServiceImpl();
 
-    final List<CakeToppingInfo> initialToppings = service.getAvailableToppings();
+    final var initialToppings = service.getAvailableToppings();
     assertNotNull(initialToppings);
     assertTrue(initialToppings.isEmpty());
 
     service.saveNewTopping(new CakeToppingInfo("Topping1", 1000));
     service.saveNewTopping(new CakeToppingInfo("Topping2", 2000));
 
-    final List<CakeToppingInfo> availableToppings = service.getAvailableToppings();
+    final var availableToppings = service.getAvailableToppings();
     assertNotNull(availableToppings);
     assertEquals(2, availableToppings.size());
-    for (final CakeToppingInfo topping : availableToppings) {
+    for (final var topping : availableToppings) {
       assertNotNull(topping.id);
       assertNotNull(topping.name);
       assertNotNull(topping.toString());
@@ -90,20 +90,20 @@ public class CakeBakingServiceImplTest {
 
   @Test
   public void testBakeCakes() throws CakeBakingException {
-    final CakeBakingServiceImpl service = new CakeBakingServiceImpl();
+    final var service = new CakeBakingServiceImpl();
 
-    final List<CakeInfo> initialCakes = service.getAllCakes();
+    final var initialCakes = service.getAllCakes();
     assertNotNull(initialCakes);
     assertTrue(initialCakes.isEmpty());
 
-    final CakeToppingInfo topping1 = new CakeToppingInfo("Topping1", 1000);
+    final var topping1 = new CakeToppingInfo("Topping1", 1000);
-    final CakeToppingInfo topping2 = new CakeToppingInfo("Topping2", 2000);
+    final var topping2 = new CakeToppingInfo("Topping2", 2000);
     service.saveNewTopping(topping1);
     service.saveNewTopping(topping2);
 
-    final CakeLayerInfo layer1 = new CakeLayerInfo("Layer1", 1000);
+    final var layer1 = new CakeLayerInfo("Layer1", 1000);
-    final CakeLayerInfo layer2 = new CakeLayerInfo("Layer2", 2000);
+    final var layer2 = new CakeLayerInfo("Layer2", 2000);
-    final CakeLayerInfo layer3 = new CakeLayerInfo("Layer3", 2000);
+    final var layer3 = new CakeLayerInfo("Layer3", 2000);
     service.saveNewLayer(layer1);
     service.saveNewLayer(layer2);
     service.saveNewLayer(layer3);
@@ -111,10 +111,10 @@ public class CakeBakingServiceImplTest {
     service.bakeNewCake(new CakeInfo(topping1, List.of(layer1, layer2)));
     service.bakeNewCake(new CakeInfo(topping2, Collections.singletonList(layer3)));
 
-    final List<CakeInfo> allCakes = service.getAllCakes();
+    final var allCakes = service.getAllCakes();
     assertNotNull(allCakes);
     assertEquals(2, allCakes.size());
-    for (final CakeInfo cakeInfo : allCakes) {
+    for (final var cakeInfo : allCakes) {
       assertNotNull(cakeInfo.id);
       assertNotNull(cakeInfo.cakeToppingInfo);
       assertNotNull(cakeInfo.cakeLayerInfos);
@@ -127,14 +127,14 @@ public class CakeBakingServiceImplTest {
 
   @Test
   public void testBakeCakeMissingTopping() {
-    final CakeBakingServiceImpl service = new CakeBakingServiceImpl();
+    final var service = new CakeBakingServiceImpl();
 
-    final CakeLayerInfo layer1 = new CakeLayerInfo("Layer1", 1000);
+    final var layer1 = new CakeLayerInfo("Layer1", 1000);
-    final CakeLayerInfo layer2 = new CakeLayerInfo("Layer2", 2000);
+    final var layer2 = new CakeLayerInfo("Layer2", 2000);
     service.saveNewLayer(layer1);
     service.saveNewLayer(layer2);
 
-    final CakeToppingInfo missingTopping = new CakeToppingInfo("Topping1", 1000);
+    final var missingTopping = new CakeToppingInfo("Topping1", 1000);
     assertThrows(CakeBakingException.class, () -> {
       service.bakeNewCake(new CakeInfo(missingTopping, List.of(layer1, layer2)));
     });
@@ -142,19 +142,19 @@ public class CakeBakingServiceImplTest {
 
   @Test
   public void testBakeCakeMissingLayer() {
-    final CakeBakingServiceImpl service = new CakeBakingServiceImpl();
+    final var service = new CakeBakingServiceImpl();
 
-    final List<CakeInfo> initialCakes = service.getAllCakes();
+    final var initialCakes = service.getAllCakes();
     assertNotNull(initialCakes);
     assertTrue(initialCakes.isEmpty());
 
-    final CakeToppingInfo topping1 = new CakeToppingInfo("Topping1", 1000);
+    final var topping1 = new CakeToppingInfo("Topping1", 1000);
     service.saveNewTopping(topping1);
 
-    final CakeLayerInfo layer1 = new CakeLayerInfo("Layer1", 1000);
+    final var layer1 = new CakeLayerInfo("Layer1", 1000);
     service.saveNewLayer(layer1);
 
-    final CakeLayerInfo missingLayer = new CakeLayerInfo("Layer2", 2000);
+    final var missingLayer = new CakeLayerInfo("Layer2", 2000);
     assertThrows(CakeBakingException.class, () -> {
       service.bakeNewCake(new CakeInfo(topping1, List.of(layer1, missingLayer)));
     });
@@ -162,19 +162,19 @@ public class CakeBakingServiceImplTest {
 
   @Test
   public void testBakeCakesUsedLayer() throws CakeBakingException {
-    final CakeBakingServiceImpl service = new CakeBakingServiceImpl();
+    final var service = new CakeBakingServiceImpl();
 
-    final List<CakeInfo> initialCakes = service.getAllCakes();
+    final var initialCakes = service.getAllCakes();
     assertNotNull(initialCakes);
     assertTrue(initialCakes.isEmpty());
 
-    final CakeToppingInfo topping1 = new CakeToppingInfo("Topping1", 1000);
+    final var topping1 = new CakeToppingInfo("Topping1", 1000);
-    final CakeToppingInfo topping2 = new CakeToppingInfo("Topping2", 2000);
+    final var topping2 = new CakeToppingInfo("Topping2", 2000);
     service.saveNewTopping(topping1);
     service.saveNewTopping(topping2);
 
-    final CakeLayerInfo layer1 = new CakeLayerInfo("Layer1", 1000);
+    final var layer1 = new CakeLayerInfo("Layer1", 1000);
-    final CakeLayerInfo layer2 = new CakeLayerInfo("Layer2", 2000);
+    final var layer2 = new CakeLayerInfo("Layer2", 2000);
     service.saveNewLayer(layer1);
     service.saveNewLayer(layer2);
 

layers/src/test/java/com/iluwatar/layers/view/CakeViewImplTest.java

@@ -68,18 +68,18 @@ public class CakeViewImplTest {
   @Test
   public void testRender() {
 
-    final List<CakeLayerInfo> layers = List.of(
+    final var layers = List.of(
             new CakeLayerInfo("layer1", 1000),
             new CakeLayerInfo("layer2", 2000),
             new CakeLayerInfo("layer3", 3000));
 
-    final CakeInfo cake = new CakeInfo(new CakeToppingInfo("topping", 1000), layers);
+    final var cake = new CakeInfo(new CakeToppingInfo("topping", 1000), layers);
-    final List<CakeInfo> cakes = List.of(cake);
+    final var cakes = List.of(cake);
 
-    final CakeBakingService bakingService = mock(CakeBakingService.class);
+    final var bakingService = mock(CakeBakingService.class);
     when(bakingService.getAllCakes()).thenReturn(cakes);
 
-    final CakeViewImpl cakeView = new CakeViewImpl(bakingService);
+    final var cakeView = new CakeViewImpl(bakingService);
 
     assertEquals(0, appender.getLogSize());
 

lazy-loading/src/main/java/com/iluwatar/lazy/loading/App.java

@@ -46,18 +46,18 @@ public class App {
   public static void main(String[] args) {
 
     // Simple lazy loader - not thread safe
-    HolderNaive holderNaive = new HolderNaive();
+    var holderNaive = new HolderNaive();
-    Heavy heavy = holderNaive.getHeavy();
+    var heavy = holderNaive.getHeavy();
     LOGGER.info("heavy={}", heavy);
 
     // Thread safe lazy loader, but with heavy synchronization on each access
-    HolderThreadSafe holderThreadSafe = new HolderThreadSafe();
+    var holderThreadSafe = new HolderThreadSafe();
-    Heavy another = holderThreadSafe.getHeavy();
+    var another = holderThreadSafe.getHeavy();
     LOGGER.info("another={}", another);
 
     // The most efficient lazy loader utilizing Java 8 features
-    Java8Holder java8Holder = new Java8Holder();
+    var java8Holder = new Java8Holder();
-    Heavy next = java8Holder.getHeavy();
+    var next = java8Holder.getHeavy();
     LOGGER.info("next={}", next);
   }
 }

lazy-loading/src/test/java/com/iluwatar/lazy/loading/HolderNaiveTest.java

@@ -36,7 +36,7 @@ public class HolderNaiveTest extends AbstractHolderTest {
 
   @Override
   Heavy getInternalHeavyValue() throws Exception {
-    final Field holderField = HolderNaive.class.getDeclaredField("heavy");
+    final var holderField = HolderNaive.class.getDeclaredField("heavy");
     holderField.setAccessible(true);
     return (Heavy) holderField.get(this.holder);
   }

lazy-loading/src/test/java/com/iluwatar/lazy/loading/HolderThreadSafeTest.java

@@ -36,7 +36,7 @@ public class HolderThreadSafeTest extends AbstractHolderTest {
 
   @Override
   Heavy getInternalHeavyValue() throws Exception {
-    final Field holderField = HolderThreadSafe.class.getDeclaredField("heavy");
+    final var holderField = HolderThreadSafe.class.getDeclaredField("heavy");
     holderField.setAccessible(true);
     return (Heavy) holderField.get(this.holder);
   }

lazy-loading/src/test/java/com/iluwatar/lazy/loading/Java8HolderTest.java

@@ -38,16 +38,16 @@ public class Java8HolderTest extends AbstractHolderTest {
 
   @Override
   Heavy getInternalHeavyValue() throws Exception {
-    final Field holderField = Java8Holder.class.getDeclaredField("heavy");
+    final var holderField = Java8Holder.class.getDeclaredField("heavy");
     holderField.setAccessible(true);
 
-    final Supplier<Heavy> supplier = (Supplier<Heavy>) holderField.get(this.holder);
+    final var supplier = (Supplier<Heavy>) holderField.get(this.holder);
-    final Class<? extends Supplier> supplierClass = supplier.getClass();
+    final var supplierClass = supplier.getClass();
 
     // This is a little fishy, but I don't know another way to test this:
     // The lazy holder is at first a lambda, but gets replaced with a new supplier after loading ...
     if (supplierClass.isLocalClass()) {
-      final Field instanceField = supplierClass.getDeclaredField("heavyInstance");
+      final var instanceField = supplierClass.getDeclaredField("heavyInstance");
       instanceField.setAccessible(true);
       return (Heavy) instanceField.get(supplier);
     } else {

leader-election/src/main/java/com/iluwatar/leaderelection/AbstractMessageManager.java

@@ -51,13 +51,13 @@ public abstract class AbstractMessageManager implements MessageManager {
    */
   protected Instance findNextInstance(int currentId) {
     Instance result = null;
-    List<Integer> candidateList = instanceMap.keySet()
+    var candidateList = instanceMap.keySet()
         .stream()
         .filter((i) -> i > currentId && instanceMap.get(i).isAlive())
         .sorted()
         .collect(Collectors.toList());
     if (candidateList.isEmpty()) {
-      int index = instanceMap.keySet()
+      var index = instanceMap.keySet()
           .stream()
           .filter((i) -> instanceMap.get(i).isAlive())
           .sorted()
@@ -65,7 +65,7 @@ public abstract class AbstractMessageManager implements MessageManager {
           .get(0);
       result = instanceMap.get(index);
     } else {
-      int index = candidateList.get(0);
+      var index = candidateList.get(0);
       result = instanceMap.get(index);
     }
     return result;

leader-election/src/main/java/com/iluwatar/leaderelection/Message.java

@@ -66,7 +66,7 @@ public class Message {
     if (o == null || getClass() != o.getClass()) {
       return false;
     }
-    Message message = (Message) o;
+    var message = (Message) o;
     return type == message.type && Objects.equals(content, message.content);
   }
 

leader-election/src/main/java/com/iluwatar/leaderelection/bully/BullyApp.java

@@ -43,13 +43,13 @@ public class BullyApp {
   public static void main(String[] args) {
 
     Map<Integer, Instance> instanceMap = new HashMap<>();
-    MessageManager messageManager = new BullyMessageManager(instanceMap);
+    var messageManager = new BullyMessageManager(instanceMap);
 
-    BullyInstance instance1 = new BullyInstance(messageManager, 1, 1);
+    var instance1 = new BullyInstance(messageManager, 1, 1);
-    BullyInstance instance2 = new BullyInstance(messageManager, 2, 1);
+    var instance2 = new BullyInstance(messageManager, 2, 1);
-    BullyInstance instance3 = new BullyInstance(messageManager, 3, 1);
+    var instance3 = new BullyInstance(messageManager, 3, 1);
-    BullyInstance instance4 = new BullyInstance(messageManager, 4, 1);
+    var instance4 = new BullyInstance(messageManager, 4, 1);
-    BullyInstance instance5 = new BullyInstance(messageManager, 5, 1);
+    var instance5 = new BullyInstance(messageManager, 5, 1);
 
     instanceMap.put(1, instance1);
     instanceMap.put(2, instance2);
@@ -59,11 +59,11 @@ public class BullyApp {
 
     instance4.onMessage(new Message(MessageType.HEARTBEAT_INVOKE, ""));
 
-    final Thread thread1 = new Thread(instance1);
+    final var thread1 = new Thread(instance1);
-    final Thread thread2 = new Thread(instance2);
+    final var thread2 = new Thread(instance2);
-    final Thread thread3 = new Thread(instance3);
+    final var thread3 = new Thread(instance3);
-    final Thread thread4 = new Thread(instance4);
+    final var thread4 = new Thread(instance4);
-    final Thread thread5 = new Thread(instance5);
+    final var thread5 = new Thread(instance5);
 
     thread1.start();
     thread2.start();

leader-election/src/main/java/com/iluwatar/leaderelection/bully/BullyMessageManager.java

@@ -51,8 +51,8 @@ public class BullyMessageManager extends AbstractMessageManager {
    */
   @Override
   public boolean sendHeartbeatMessage(int leaderId) {
-    Instance leaderInstance = instanceMap.get(leaderId);
+    var leaderInstance = instanceMap.get(leaderId);
-    boolean alive = leaderInstance.isAlive();
+    var alive = leaderInstance.isAlive();
     return alive;
   }
 
@@ -65,13 +65,12 @@ public class BullyMessageManager extends AbstractMessageManager {
    */
   @Override
   public boolean sendElectionMessage(int currentId, String content) {
-    List<Integer> candidateList = findElectionCandidateInstanceList(currentId);
+    var candidateList = findElectionCandidateInstanceList(currentId);
     if (candidateList.isEmpty()) {
       return true;
     } else {
-      Message electionMessage = new Message(MessageType.ELECTION_INVOKE, "");
+      var electionMessage = new Message(MessageType.ELECTION_INVOKE, "");
-      candidateList.stream()
+      candidateList.stream().forEach((i) -> instanceMap.get(i).onMessage(electionMessage));
-          .forEach((i) -> instanceMap.get(i).onMessage(electionMessage));
       return false;
     }
   }
@@ -85,7 +84,7 @@ public class BullyMessageManager extends AbstractMessageManager {
    */
   @Override
   public boolean sendLeaderMessage(int currentId, int leaderId) {
-    Message leaderMessage = new Message(MessageType.LEADER, String.valueOf(leaderId));
+    var leaderMessage = new Message(MessageType.LEADER, String.valueOf(leaderId));
     instanceMap.keySet()
         .stream()
         .filter((i) -> i != currentId)
@@ -100,8 +99,8 @@ public class BullyMessageManager extends AbstractMessageManager {
    */
   @Override
   public void sendHeartbeatInvokeMessage(int currentId) {
-    Instance nextInstance = this.findNextInstance(currentId);
+    var nextInstance = this.findNextInstance(currentId);
-    Message heartbeatInvokeMessage = new Message(MessageType.HEARTBEAT_INVOKE, "");
+    var heartbeatInvokeMessage = new Message(MessageType.HEARTBEAT_INVOKE, "");
     nextInstance.onMessage(heartbeatInvokeMessage);
   }
 

leader-election/src/main/java/com/iluwatar/leaderelection/ring/RingApp.java

@@ -43,13 +43,13 @@ public class RingApp {
   public static void main(String[] args) {
 
     Map<Integer, Instance> instanceMap = new HashMap<>();
-    MessageManager messageManager = new RingMessageManager(instanceMap);
+    var messageManager = new RingMessageManager(instanceMap);
 
-    RingInstance instance1 = new RingInstance(messageManager, 1, 1);
+    var instance1 = new RingInstance(messageManager, 1, 1);
-    RingInstance instance2 = new RingInstance(messageManager, 2, 1);
+    var instance2 = new RingInstance(messageManager, 2, 1);
-    RingInstance instance3 = new RingInstance(messageManager, 3, 1);
+    var instance3 = new RingInstance(messageManager, 3, 1);
-    RingInstance instance4 = new RingInstance(messageManager, 4, 1);
+    var instance4 = new RingInstance(messageManager, 4, 1);
-    RingInstance instance5 = new RingInstance(messageManager, 5, 1);
+    var instance5 = new RingInstance(messageManager, 5, 1);
 
     instanceMap.put(1, instance1);
     instanceMap.put(2, instance2);
@@ -59,11 +59,11 @@ public class RingApp {
 
     instance2.onMessage(new Message(MessageType.HEARTBEAT_INVOKE, ""));
 
-    final Thread thread1 = new Thread(instance1);
+    final var thread1 = new Thread(instance1);
-    final Thread thread2 = new Thread(instance2);
+    final var thread2 = new Thread(instance2);
-    final Thread thread3 = new Thread(instance3);
+    final var thread3 = new Thread(instance3);
-    final Thread thread4 = new Thread(instance4);
+    final var thread4 = new Thread(instance4);
-    final Thread thread5 = new Thread(instance5);
+    final var thread5 = new Thread(instance5);
 
     thread1.start();
     thread2.start();

leader-election/src/main/java/com/iluwatar/leaderelection/ring/RingInstance.java

@@ -62,7 +62,7 @@ public class RingInstance extends AbstractInstance {
   @Override
   protected void handleHeartbeatInvokeMessage() {
     try {
-      boolean isLeaderAlive = messageManager.sendHeartbeatMessage(this.leaderId);
+      var isLeaderAlive = messageManager.sendHeartbeatMessage(this.leaderId);
       if (isLeaderAlive) {
         LOGGER.info("Instance " + localId + "- Leader is alive. Start next heartbeat in 5 second.");
         Thread.sleep(HEARTBEAT_INTERVAL);
@@ -84,15 +84,14 @@ public class RingInstance extends AbstractInstance {
    */
   @Override
   protected void handleElectionMessage(Message message) {
-    String content = message.getContent();
+    var content = message.getContent();
     LOGGER.info("Instance " + localId + " - Election Message: " + content);
-    List<Integer> candidateList =
+    var candidateList = Arrays.stream(content.trim().split(","))
-        Arrays.stream(content.trim().split(","))
+        .map(Integer::valueOf)
-            .map(Integer::valueOf)
+        .sorted()
-            .sorted()
+        .collect(Collectors.toList());
-            .collect(Collectors.toList());
     if (candidateList.contains(localId)) {
-      int newLeaderId = candidateList.get(0);
+      var newLeaderId = candidateList.get(0);
       LOGGER.info("Instance " + localId + " - New leader should be " + newLeaderId + ".");
       messageManager.sendLeaderMessage(localId, newLeaderId);
     } else {
@@ -107,7 +106,7 @@ public class RingInstance extends AbstractInstance {
    */
   @Override
   protected void handleLeaderMessage(Message message) {
-    int newLeaderId = Integer.valueOf(message.getContent());
+    var newLeaderId = Integer.valueOf(message.getContent());
     if (this.leaderId != newLeaderId) {
       LOGGER.info("Instance " + localId + " - Update leaderID");
       this.leaderId = newLeaderId;

leader-election/src/main/java/com/iluwatar/leaderelection/ring/RingMessageManager.java

@@ -49,8 +49,8 @@ public class RingMessageManager extends AbstractMessageManager {
    */
   @Override
   public boolean sendHeartbeatMessage(int leaderId) {
-    Instance leaderInstance = instanceMap.get(leaderId);
+    var leaderInstance = instanceMap.get(leaderId);
-    boolean alive = leaderInstance.isAlive();
+    var alive = leaderInstance.isAlive();
     return alive;
   }
 
@@ -64,8 +64,8 @@ public class RingMessageManager extends AbstractMessageManager {
    */
   @Override
   public boolean sendElectionMessage(int currentId, String content) {
-    Instance nextInstance = this.findNextInstance(currentId);
+    var nextInstance = this.findNextInstance(currentId);
-    Message electionMessage = new Message(MessageType.ELECTION, content);
+    var electionMessage = new Message(MessageType.ELECTION, content);
     nextInstance.onMessage(electionMessage);
     return true;
   }
@@ -79,8 +79,8 @@ public class RingMessageManager extends AbstractMessageManager {
    */
   @Override
   public boolean sendLeaderMessage(int currentId, int leaderId) {
-    Instance nextInstance = this.findNextInstance(currentId);
+    var nextInstance = this.findNextInstance(currentId);
-    Message leaderMessage = new Message(MessageType.LEADER, String.valueOf(leaderId));
+    var leaderMessage = new Message(MessageType.LEADER, String.valueOf(leaderId));
     nextInstance.onMessage(leaderMessage);
     return true;
   }
@@ -92,8 +92,8 @@ public class RingMessageManager extends AbstractMessageManager {
    */
   @Override
   public void sendHeartbeatInvokeMessage(int currentId) {
-    Instance nextInstance = this.findNextInstance(currentId);
+    var nextInstance = this.findNextInstance(currentId);
-    Message heartbeatInvokeMessage = new Message(MessageType.HEARTBEAT_INVOKE, "");
+    var heartbeatInvokeMessage = new Message(MessageType.HEARTBEAT_INVOKE, "");
     nextInstance.onMessage(heartbeatInvokeMessage);
   }
 

leader-election/src/test/java/com/iluwatar/leaderelection/MessageTest.java

@@ -34,14 +34,14 @@ public class MessageTest {
 
   @Test
   public void testGetType() {
-    Message message = new Message(MessageType.HEARTBEAT, "");
+    var message = new Message(MessageType.HEARTBEAT, "");
     assertEquals(MessageType.HEARTBEAT, message.getType());
   }
 
   @Test
   public void testGetContent() {
-    String content = "test";
+    var content = "test";
-    Message message = new Message(MessageType.HEARTBEAT, content);
+    var message = new Message(MessageType.HEARTBEAT, content);
     assertEquals(content, message.getContent());
   }
 

leader-election/src/test/java/com/iluwatar/leaderelection/bully/BullyMessageManagerTest.java

@@ -39,29 +39,29 @@ public class BullyMessageManagerTest {
 
   @Test
   public void testSendHeartbeatMessage() {
-    Instance instance1 = new BullyInstance(null, 1, 1);
+    var instance1 = new BullyInstance(null, 1, 1);
     Map<Integer, Instance> instanceMap = Map.of(1, instance1);
-    MessageManager messageManager = new BullyMessageManager(instanceMap);
+    var messageManager = new BullyMessageManager(instanceMap);
     assertTrue(messageManager.sendHeartbeatMessage(1));
   }
 
   @Test
   public void testSendElectionMessageNotAccepted() {
     try {
-      Instance instance1 = new BullyInstance(null, 1, 1);
+      var instance1 = new BullyInstance(null, 1, 1);
-      Instance instance2 = new BullyInstance(null, 1, 2);
+      var instance2 = new BullyInstance(null, 1, 2);
-      Instance instance3 = new BullyInstance(null, 1, 3);
+      var instance3 = new BullyInstance(null, 1, 3);
-      Instance instance4 = new BullyInstance(null, 1, 4);
+      var instance4 = new BullyInstance(null, 1, 4);
       Map<Integer, Instance> instanceMap = Map.of(1, instance1, 2, instance2, 3, instance3, 4, instance4);
       instance1.setAlive(false);
-      MessageManager messageManager = new BullyMessageManager(instanceMap);
+      var messageManager = new BullyMessageManager(instanceMap);
-      boolean result = messageManager.sendElectionMessage(3, "3");
+      var result = messageManager.sendElectionMessage(3, "3");
-      Class instanceClass = AbstractInstance.class;
+      var instanceClass = AbstractInstance.class;
-      Field messageQueueField = instanceClass.getDeclaredField("messageQueue");
+      var messageQueueField = instanceClass.getDeclaredField("messageQueue");
       messageQueueField.setAccessible(true);
-      Message message2 = ((Queue<Message>) messageQueueField.get(instance2)).poll();
+      var message2 = ((Queue<Message>) messageQueueField.get(instance2)).poll();
-      int instance4QueueSize = ((Queue<Message>) messageQueueField.get(instance4)).size();
+      var instance4QueueSize = ((Queue<Message>) messageQueueField.get(instance4)).size();
-      Message expectedMessage = new Message(MessageType.ELECTION_INVOKE, "");
+      var expectedMessage = new Message(MessageType.ELECTION_INVOKE, "");
       assertEquals(message2, expectedMessage);
       assertEquals(instance4QueueSize, 0);
       assertEquals(result, false);
@@ -72,34 +72,34 @@ public class BullyMessageManagerTest {
 
   @Test
   public void testElectionMessageAccepted() {
-    Instance instance1 = new BullyInstance(null, 1, 1);
+    var instance1 = new BullyInstance(null, 1, 1);
-    Instance instance2 = new BullyInstance(null, 1, 2);
+    var instance2 = new BullyInstance(null, 1, 2);
-    Instance instance3 = new BullyInstance(null, 1, 3);
+    var instance3 = new BullyInstance(null, 1, 3);
-    Instance instance4 = new BullyInstance(null, 1, 4);
+    var instance4 = new BullyInstance(null, 1, 4);
     Map<Integer, Instance> instanceMap = Map.of(1, instance1, 2, instance2, 3, instance3, 4, instance4);
     instance1.setAlive(false);
-    MessageManager messageManager = new BullyMessageManager(instanceMap);
+    var messageManager = new BullyMessageManager(instanceMap);
-    boolean result = messageManager.sendElectionMessage(2, "2");
+    var result = messageManager.sendElectionMessage(2, "2");
     assertEquals(result, true);
   }
 
   @Test
   public void testSendLeaderMessage() {
     try {
-      Instance instance1 = new BullyInstance(null, 1, 1);
+      var instance1 = new BullyInstance(null, 1, 1);
-      Instance instance2 = new BullyInstance(null, 1, 2);
+      var instance2 = new BullyInstance(null, 1, 2);
-      Instance instance3 = new BullyInstance(null, 1, 3);
+      var instance3 = new BullyInstance(null, 1, 3);
-      Instance instance4 = new BullyInstance(null, 1, 4);
+      var instance4 = new BullyInstance(null, 1, 4);
       Map<Integer, Instance> instanceMap = Map.of(1, instance1, 2, instance2, 3, instance3, 4, instance4);
       instance1.setAlive(false);
-      MessageManager messageManager = new BullyMessageManager(instanceMap);
+      var messageManager = new BullyMessageManager(instanceMap);
       messageManager.sendLeaderMessage(2, 2);
-      Class instanceClass = AbstractInstance.class;
+      var instanceClass = AbstractInstance.class;
-      Field messageQueueField = instanceClass.getDeclaredField("messageQueue");
+      var messageQueueField = instanceClass.getDeclaredField("messageQueue");
       messageQueueField.setAccessible(true);
-      Message message3 = ((Queue<Message>) messageQueueField.get(instance3)).poll();
+      var message3 = ((Queue<Message>) messageQueueField.get(instance3)).poll();
-      Message message4 = ((Queue<Message>) messageQueueField.get(instance4)).poll();
+      var message4 = ((Queue<Message>) messageQueueField.get(instance4)).poll();
-      Message expectedMessage = new Message(MessageType.LEADER, "2");
+      var expectedMessage = new Message(MessageType.LEADER, "2");
       assertEquals(message3, expectedMessage);
       assertEquals(message4, expectedMessage);
     } catch (IllegalAccessException | NoSuchFieldException e) {
@@ -110,17 +110,17 @@ public class BullyMessageManagerTest {
   @Test
   public void testSendHeartbeatInvokeMessage() {
     try {
-      Instance instance1 = new BullyInstance(null, 1, 1);
+      var instance1 = new BullyInstance(null, 1, 1);
-      Instance instance2 = new BullyInstance(null, 1, 2);
+      var instance2 = new BullyInstance(null, 1, 2);
-      Instance instance3 = new BullyInstance(null, 1, 3);
+      var instance3 = new BullyInstance(null, 1, 3);
       Map<Integer, Instance> instanceMap = Map.of(1, instance1, 2, instance2, 3, instance3);
-      MessageManager messageManager = new BullyMessageManager(instanceMap);
+      var messageManager = new BullyMessageManager(instanceMap);
       messageManager.sendHeartbeatInvokeMessage(2);
-      Message message = new Message(MessageType.HEARTBEAT_INVOKE, "");
+      var message = new Message(MessageType.HEARTBEAT_INVOKE, "");
-      Class instanceClass = AbstractInstance.class;
+      var instanceClass = AbstractInstance.class;
-      Field messageQueueField = instanceClass.getDeclaredField("messageQueue");
+      var messageQueueField = instanceClass.getDeclaredField("messageQueue");
       messageQueueField.setAccessible(true);
-      Message messageSent = ((Queue<Message>) messageQueueField.get(instance3)).poll();
+      var messageSent = ((Queue<Message>) messageQueueField.get(instance3)).poll();
       assertEquals(messageSent.getType(), message.getType());
       assertEquals(messageSent.getContent(), message.getContent());
     } catch (NoSuchFieldException | IllegalAccessException e) {

leader-election/src/test/java/com/iluwatar/leaderelection/bully/BullyinstanceTest.java

@@ -41,11 +41,11 @@ public class BullyinstanceTest {
   @Test
   public void testOnMessage() {
     try {
-      final BullyInstance bullyInstance = new BullyInstance(null, 1, 1);
+      final var bullyInstance = new BullyInstance(null, 1, 1);
-      Message bullyMessage = new Message(MessageType.HEARTBEAT, "");
+      var bullyMessage = new Message(MessageType.HEARTBEAT, "");
       bullyInstance.onMessage(bullyMessage);
-      Class instanceClass = AbstractInstance.class;
+      var instanceClass = AbstractInstance.class;
-      Field messageQueueField = instanceClass.getDeclaredField("messageQueue");
+      var messageQueueField = instanceClass.getDeclaredField("messageQueue");
       messageQueueField.setAccessible(true);
       assertEquals(bullyMessage, ((Queue<Message>) messageQueueField.get(bullyInstance)).poll());
     } catch (IllegalAccessException | NoSuchFieldException e) {
@@ -57,9 +57,9 @@ public class BullyinstanceTest {
   @Test
   public void testIsAlive() {
     try {
-      final BullyInstance bullyInstance = new BullyInstance(null, 1, 1);
+      final var bullyInstance = new BullyInstance(null, 1, 1);
-      Class instanceClass = AbstractInstance.class;
+      var instanceClass = AbstractInstance.class;
-      Field aliveField = instanceClass.getDeclaredField("alive");
+      var aliveField = instanceClass.getDeclaredField("alive");
       aliveField.setAccessible(true);
       aliveField.set(bullyInstance, false);
       assertFalse(bullyInstance.isAlive());
@@ -70,7 +70,7 @@ public class BullyinstanceTest {
 
   @Test
   public void testSetAlive() {
-    final BullyInstance bullyInstance = new BullyInstance(null, 1, 1);
+    final var bullyInstance = new BullyInstance(null, 1, 1);
     bullyInstance.setAlive(false);
     assertFalse(bullyInstance.isAlive());
   }

leader-election/src/test/java/com/iluwatar/leaderelection/ring/RingInstanceTest.java

@@ -41,11 +41,11 @@ public class RingInstanceTest {
   @Test
   public void testOnMessage() {
     try {
-      final RingInstance ringInstance = new RingInstance(null, 1, 1);
+      final var ringInstance = new RingInstance(null, 1, 1);
-      Message ringMessage = new Message(MessageType.HEARTBEAT, "");
+      var ringMessage = new Message(MessageType.HEARTBEAT, "");
       ringInstance.onMessage(ringMessage);
-      Class ringInstanceClass = AbstractInstance.class;
+      var ringInstanceClass = AbstractInstance.class;
-      Field messageQueueField = ringInstanceClass.getDeclaredField("messageQueue");
+      var messageQueueField = ringInstanceClass.getDeclaredField("messageQueue");
       messageQueueField.setAccessible(true);
       assertEquals(ringMessage, ((Queue<Message>) messageQueueField.get(ringInstance)).poll());
     } catch (IllegalAccessException | NoSuchFieldException e) {
@@ -56,9 +56,9 @@ public class RingInstanceTest {
   @Test
   public void testIsAlive() {
     try {
-      final RingInstance ringInstance = new RingInstance(null, 1, 1);
+      final var ringInstance = new RingInstance(null, 1, 1);
-      Class ringInstanceClass = AbstractInstance.class;
+      var ringInstanceClass = AbstractInstance.class;
-      Field aliveField = ringInstanceClass.getDeclaredField("alive");
+      var aliveField = ringInstanceClass.getDeclaredField("alive");
       aliveField.setAccessible(true);
       aliveField.set(ringInstance, false);
       assertFalse(ringInstance.isAlive());
@@ -69,7 +69,7 @@ public class RingInstanceTest {
 
   @Test
   public void testSetAlive() {
-    final RingInstance ringInstance = new RingInstance(null, 1, 1);
+    final var ringInstance = new RingInstance(null, 1, 1);
     ringInstance.setAlive(false);
     assertFalse(ringInstance.isAlive());
   }

leader-election/src/test/java/com/iluwatar/leaderelection/ring/RingMessageManagerTest.java

@@ -39,27 +39,27 @@ public class RingMessageManagerTest {
 
   @Test
   public void testSendHeartbeatMessage() {
-    Instance instance1 = new RingInstance(null, 1, 1);
+    var instance1 = new RingInstance(null, 1, 1);
     Map<Integer, Instance> instanceMap = Map.of(1, instance1);
-    MessageManager messageManager = new RingMessageManager(instanceMap);
+    var messageManager = new RingMessageManager(instanceMap);
     assertTrue(messageManager.sendHeartbeatMessage(1));
   }
 
   @Test
   public void testSendElectionMessage() {
     try {
-      Instance instance1 = new RingInstance(null, 1, 1);
+      var instance1 = new RingInstance(null, 1, 1);
-      Instance instance2 = new RingInstance(null, 1, 2);
+      var instance2 = new RingInstance(null, 1, 2);
-      Instance instance3 = new RingInstance(null, 1, 3);
+      var instance3 = new RingInstance(null, 1, 3);
       Map<Integer, Instance> instanceMap = Map.of(1, instance1, 2, instance2, 3, instance3);
-      MessageManager messageManager = new RingMessageManager(instanceMap);
+      var messageManager = new RingMessageManager(instanceMap);
-      String messageContent = "2";
+      var messageContent = "2";
       messageManager.sendElectionMessage(2, messageContent);
-      Message ringMessage = new Message(MessageType.ELECTION, messageContent);
+      var ringMessage = new Message(MessageType.ELECTION, messageContent);
-      Class instanceClass = AbstractInstance.class;
+      var instanceClass = AbstractInstance.class;
-      Field messageQueueField = instanceClass.getDeclaredField("messageQueue");
+      var messageQueueField = instanceClass.getDeclaredField("messageQueue");
       messageQueueField.setAccessible(true);
-      Message ringMessageSent = ((Queue<Message>) messageQueueField.get(instance3)).poll();
+      var ringMessageSent = ((Queue<Message>) messageQueueField.get(instance3)).poll();
       assertEquals(ringMessageSent.getType(), ringMessage.getType());
       assertEquals(ringMessageSent.getContent(), ringMessage.getContent());
     } catch (NoSuchFieldException | IllegalAccessException e) {
@@ -70,18 +70,18 @@ public class RingMessageManagerTest {
   @Test
   public void testSendLeaderMessage() {
     try {
-      Instance instance1 = new RingInstance(null, 1, 1);
+      var instance1 = new RingInstance(null, 1, 1);
-      Instance instance2 = new RingInstance(null, 1, 2);
+      var instance2 = new RingInstance(null, 1, 2);
-      Instance instance3 = new RingInstance(null, 1, 3);
+      var instance3 = new RingInstance(null, 1, 3);
       Map<Integer, Instance> instanceMap = Map.of(1, instance1, 2, instance2, 3, instance3);
-      MessageManager messageManager = new RingMessageManager(instanceMap);
+      var messageManager = new RingMessageManager(instanceMap);
-      String messageContent = "3";
+      var messageContent = "3";
       messageManager.sendLeaderMessage(2, 3);
-      Message ringMessage = new Message(MessageType.LEADER, messageContent);
+      var ringMessage = new Message(MessageType.LEADER, messageContent);
-      Class instanceClass = AbstractInstance.class;
+      var instanceClass = AbstractInstance.class;
-      Field messageQueueField = instanceClass.getDeclaredField("messageQueue");
+      var messageQueueField = instanceClass.getDeclaredField("messageQueue");
       messageQueueField.setAccessible(true);
-      Message ringMessageSent = ((Queue<Message>) messageQueueField.get(instance3)).poll();
+      var ringMessageSent = ((Queue<Message>) messageQueueField.get(instance3)).poll();
       assertEquals(ringMessageSent, ringMessage);
     } catch (NoSuchFieldException | IllegalAccessException e) {
       fail("Error to access private field.");
@@ -91,17 +91,17 @@ public class RingMessageManagerTest {
   @Test
   public void testSendHeartbeatInvokeMessage() {
     try {
-      Instance instance1 = new RingInstance(null, 1, 1);
+      var instance1 = new RingInstance(null, 1, 1);
-      Instance instance2 = new RingInstance(null, 1, 2);
+      var instance2 = new RingInstance(null, 1, 2);
-      Instance instance3 = new RingInstance(null, 1, 3);
+      var instance3 = new RingInstance(null, 1, 3);
       Map<Integer, Instance> instanceMap = Map.of(1, instance1, 2, instance2, 3, instance3);
-      MessageManager messageManager = new RingMessageManager(instanceMap);
+      var messageManager = new RingMessageManager(instanceMap);
       messageManager.sendHeartbeatInvokeMessage(2);
-      Message ringMessage = new Message(MessageType.HEARTBEAT_INVOKE, "");
+      var ringMessage = new Message(MessageType.HEARTBEAT_INVOKE, "");
-      Class instanceClass = AbstractInstance.class;
+      var instanceClass = AbstractInstance.class;
-      Field messageQueueField = instanceClass.getDeclaredField("messageQueue");
+      var messageQueueField = instanceClass.getDeclaredField("messageQueue");
       messageQueueField.setAccessible(true);
-      Message ringMessageSent = ((Queue<Message>) messageQueueField.get(instance3)).poll();
+      var ringMessageSent = ((Queue<Message>) messageQueueField.get(instance3)).poll();
       assertEquals(ringMessageSent.getType(), ringMessage.getType());
       assertEquals(ringMessageSent.getContent(), ringMessage.getContent());
     } catch (NoSuchFieldException | IllegalAccessException e) {