Use java 11 (#1050)

hexagonal/src/main/java/com/iluwatar/hexagonal/sampledata/SampleData.java

@@ -31,7 +31,6 @@ import com.iluwatar.hexagonal.domain.LotteryTicket;
 import com.iluwatar.hexagonal.domain.LotteryTicketId;
 import com.iluwatar.hexagonal.domain.PlayerDetails;
 
-import java.util.ArrayList;
 import java.util.List;
 import java.util.Random;
 
@@ -44,46 +43,47 @@ public class SampleData {
   private static final Random RANDOM = new Random();
 
   static {
-    PLAYERS = new ArrayList<>();
+    PLAYERS = List.of(
-    PLAYERS.add(new PlayerDetails("john@google.com", "312-342", "+3242434242"));
+            new PlayerDetails("john@google.com", "312-342", "+3242434242"),
-    PLAYERS.add(new PlayerDetails("mary@google.com", "234-987", "+23452346"));
+            new PlayerDetails("mary@google.com", "234-987", "+23452346"),
-    PLAYERS.add(new PlayerDetails("steve@google.com", "833-836", "+63457543"));
+            new PlayerDetails("steve@google.com", "833-836", "+63457543"),
-    PLAYERS.add(new PlayerDetails("wayne@google.com", "319-826", "+24626"));
+            new PlayerDetails("wayne@google.com", "319-826", "+24626"),
-    PLAYERS.add(new PlayerDetails("johnie@google.com", "983-322", "+3635635"));
+            new PlayerDetails("johnie@google.com", "983-322", "+3635635"),
-    PLAYERS.add(new PlayerDetails("andy@google.com", "934-734", "+0898245"));
+            new PlayerDetails("andy@google.com", "934-734", "+0898245"),
-    PLAYERS.add(new PlayerDetails("richard@google.com", "536-738", "+09845325"));
+            new PlayerDetails("richard@google.com", "536-738", "+09845325"),
-    PLAYERS.add(new PlayerDetails("kevin@google.com", "453-936", "+2423532"));
+            new PlayerDetails("kevin@google.com", "453-936", "+2423532"),
-    PLAYERS.add(new PlayerDetails("arnold@google.com", "114-988", "+5646346524"));
+            new PlayerDetails("arnold@google.com", "114-988", "+5646346524"),
-    PLAYERS.add(new PlayerDetails("ian@google.com", "663-765", "+928394235"));
+            new PlayerDetails("ian@google.com", "663-765", "+928394235"),
-    PLAYERS.add(new PlayerDetails("robin@google.com", "334-763", "+35448"));
+            new PlayerDetails("robin@google.com", "334-763", "+35448"),
-    PLAYERS.add(new PlayerDetails("ted@google.com", "735-964", "+98752345"));
+            new PlayerDetails("ted@google.com", "735-964", "+98752345"),
-    PLAYERS.add(new PlayerDetails("larry@google.com", "734-853", "+043842423"));
+            new PlayerDetails("larry@google.com", "734-853", "+043842423"),
-    PLAYERS.add(new PlayerDetails("calvin@google.com", "334-746", "+73294135"));
+            new PlayerDetails("calvin@google.com", "334-746", "+73294135"),
-    PLAYERS.add(new PlayerDetails("jacob@google.com", "444-766", "+358042354"));
+            new PlayerDetails("jacob@google.com", "444-766", "+358042354"),
-    PLAYERS.add(new PlayerDetails("edwin@google.com", "895-345", "+9752435"));
+            new PlayerDetails("edwin@google.com", "895-345", "+9752435"),
-    PLAYERS.add(new PlayerDetails("mary@google.com", "760-009", "+34203542"));
+            new PlayerDetails("mary@google.com", "760-009", "+34203542"),
-    PLAYERS.add(new PlayerDetails("lolita@google.com", "425-907", "+9872342"));
+            new PlayerDetails("lolita@google.com", "425-907", "+9872342"),
-    PLAYERS.add(new PlayerDetails("bruno@google.com", "023-638", "+673824122"));
+            new PlayerDetails("bruno@google.com", "023-638", "+673824122"),
-    PLAYERS.add(new PlayerDetails("peter@google.com", "335-886", "+5432503945"));
+            new PlayerDetails("peter@google.com", "335-886", "+5432503945"),
-    PLAYERS.add(new PlayerDetails("warren@google.com", "225-946", "+9872341324"));
+            new PlayerDetails("warren@google.com", "225-946", "+9872341324"),
-    PLAYERS.add(new PlayerDetails("monica@google.com", "265-748", "+134124"));
+            new PlayerDetails("monica@google.com", "265-748", "+134124"),
-    PLAYERS.add(new PlayerDetails("ollie@google.com", "190-045", "+34453452"));
+            new PlayerDetails("ollie@google.com", "190-045", "+34453452"),
-    PLAYERS.add(new PlayerDetails("yngwie@google.com", "241-465", "+9897641231"));
+            new PlayerDetails("yngwie@google.com", "241-465", "+9897641231"),
-    PLAYERS.add(new PlayerDetails("lars@google.com", "746-936", "+42345298345"));
+            new PlayerDetails("lars@google.com", "746-936", "+42345298345"),
-    PLAYERS.add(new PlayerDetails("bobbie@google.com", "946-384", "+79831742"));
+            new PlayerDetails("bobbie@google.com", "946-384", "+79831742"),
-    PLAYERS.add(new PlayerDetails("tyron@google.com", "310-992", "+0498837412"));
+            new PlayerDetails("tyron@google.com", "310-992", "+0498837412"),
-    PLAYERS.add(new PlayerDetails("tyrell@google.com", "032-045", "+67834134"));
+            new PlayerDetails("tyrell@google.com", "032-045", "+67834134"),
-    PLAYERS.add(new PlayerDetails("nadja@google.com", "000-346", "+498723"));
+            new PlayerDetails("nadja@google.com", "000-346", "+498723"),
-    PLAYERS.add(new PlayerDetails("wendy@google.com", "994-989", "+987324454"));
+            new PlayerDetails("wendy@google.com", "994-989", "+987324454"),
-    PLAYERS.add(new PlayerDetails("luke@google.com", "546-634", "+987642435"));
+            new PlayerDetails("luke@google.com", "546-634", "+987642435"),
-    PLAYERS.add(new PlayerDetails("bjorn@google.com", "342-874", "+7834325"));
+            new PlayerDetails("bjorn@google.com", "342-874", "+7834325"),
-    PLAYERS.add(new PlayerDetails("lisa@google.com", "024-653", "+980742154"));
+            new PlayerDetails("lisa@google.com", "024-653", "+980742154"),
-    PLAYERS.add(new PlayerDetails("anton@google.com", "834-935", "+876423145"));
+            new PlayerDetails("anton@google.com", "834-935", "+876423145"),
-    PLAYERS.add(new PlayerDetails("bruce@google.com", "284-936", "+09843212345"));
+            new PlayerDetails("bruce@google.com", "284-936", "+09843212345"),
-    PLAYERS.add(new PlayerDetails("ray@google.com", "843-073", "+678324123"));
+            new PlayerDetails("ray@google.com", "843-073", "+678324123"),
-    PLAYERS.add(new PlayerDetails("ron@google.com", "637-738", "+09842354"));
+            new PlayerDetails("ron@google.com", "637-738", "+09842354"),
-    PLAYERS.add(new PlayerDetails("xavier@google.com", "143-947", "+375245"));
+            new PlayerDetails("xavier@google.com", "143-947", "+375245"),
-    PLAYERS.add(new PlayerDetails("harriet@google.com", "842-404", "+131243252"));
+            new PlayerDetails("harriet@google.com", "842-404", "+131243252")
+    );
     InMemoryBank wireTransfers = new InMemoryBank();
     for (PlayerDetails player : PLAYERS) {
       wireTransfers.setFunds(player.getBankAccount(),

hexagonal/src/main/java/com/iluwatar/hexagonal/service/LotteryConsoleServiceImpl.java

@@ -27,10 +27,9 @@ import com.iluwatar.hexagonal.banking.WireTransfers;
 import com.iluwatar.hexagonal.domain.*;
 import org.slf4j.Logger;
 
-import java.util.HashSet;
+import java.util.*;
-import java.util.Optional;
+import java.util.stream.Collectors;
-import java.util.Scanner;
+import java.util.stream.IntStream;
-import java.util.Set;
 
 /**
  * Console implementation for lottery console service
@@ -88,10 +87,7 @@ public class LotteryConsoleServiceImpl implements LotteryConsoleService {
     String numbers = readString( scanner );
     try {
       String[] parts = numbers.split( "," );
-      Set<Integer> chosen = new HashSet<>();
+      Set<Integer> chosen = Arrays.stream(parts).map(Integer::parseInt).collect(Collectors.toSet());
-      for (int i = 0; i < 4; i++) {
-        chosen.add( Integer.parseInt( parts[i] ) );
-      }
       LotteryNumbers lotteryNumbers = LotteryNumbers.create( chosen );
       LotteryTicket lotteryTicket = new LotteryTicket( new LotteryTicketId(), details, lotteryNumbers );
       Optional<LotteryTicketId> id = service.submitTicket( lotteryTicket );

hexagonal/src/test/java/com/iluwatar/hexagonal/domain/LotteryNumbersTest.java

@@ -27,6 +27,7 @@ import org.junit.jupiter.api.Test;
 
 import java.util.Arrays;
 import java.util.HashSet;
+import java.util.Set;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertNotEquals;
@@ -43,7 +44,7 @@ class LotteryNumbersTest {
   @Test
   void testGivenNumbers() {
     LotteryNumbers numbers = LotteryNumbers.create(
-            new HashSet<>(Arrays.asList(1, 2, 3, 4)));
+            Set.of(1, 2, 3, 4));
     assertEquals(numbers.getNumbers().size(), 4);
     assertTrue(numbers.getNumbers().contains(1));
     assertTrue(numbers.getNumbers().contains(2));
@@ -54,7 +55,7 @@ class LotteryNumbersTest {
   @Test
   void testNumbersCantBeModified() {
     LotteryNumbers numbers = LotteryNumbers.create(
-            new HashSet<>(Arrays.asList(1, 2, 3, 4)));
+            Set.of(1, 2, 3, 4));
     assertThrows(UnsupportedOperationException.class, () -> numbers.getNumbers().add(5));
   }
   
@@ -67,12 +68,12 @@ class LotteryNumbersTest {
   @Test
   void testEquals() {
     LotteryNumbers numbers1 = LotteryNumbers.create(
-            new HashSet<>(Arrays.asList(1, 2, 3, 4)));
+            Set.of(1, 2, 3, 4));
     LotteryNumbers numbers2 = LotteryNumbers.create(
-            new HashSet<>(Arrays.asList(1, 2, 3, 4)));
+            Set.of(1, 2, 3, 4));
     assertEquals(numbers1, numbers2);
     LotteryNumbers numbers3 = LotteryNumbers.create(
-            new HashSet<>(Arrays.asList(11, 12, 13, 14)));
+            Set.of(11, 12, 13, 14));
     assertNotEquals(numbers1, numbers3);
   }
 }

hexagonal/src/test/java/com/iluwatar/hexagonal/domain/LotteryTest.java

@@ -33,10 +33,7 @@ import com.iluwatar.hexagonal.test.LotteryTestUtils;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 
-import java.util.Arrays;
+import java.util.*;
-import java.util.HashSet;
-import java.util.Map;
-import java.util.Optional;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertNotEquals;
@@ -76,13 +73,13 @@ class LotteryTest {
     
     // players submit the lottery tickets
     Optional<LotteryTicketId> ticket1 = service.submitTicket(LotteryTestUtils.createLotteryTicket("cvt@bbb.com",
-        "123-12312", "+32425255", new HashSet<>(Arrays.asList(1, 2, 3, 4))));
+        "123-12312", "+32425255", Set.of(1, 2, 3, 4)));
     assertTrue(ticket1.isPresent());
     Optional<LotteryTicketId> ticket2 = service.submitTicket(LotteryTestUtils.createLotteryTicket("ant@bac.com",
-        "123-12312", "+32423455", new HashSet<>(Arrays.asList(11, 12, 13, 14))));
+        "123-12312", "+32423455", Set.of(11, 12, 13, 14)));
     assertTrue(ticket2.isPresent());
     Optional<LotteryTicketId> ticket3 = service.submitTicket(LotteryTestUtils.createLotteryTicket("arg@boo.com",
-        "123-12312", "+32421255", new HashSet<>(Arrays.asList(6, 8, 13, 19))));
+        "123-12312", "+32421255", Set.of(6, 8, 13, 19)));
     assertTrue(ticket3.isPresent());
     assertEquals(3, administration.getAllSubmittedTickets().size());
     

hexagonal/src/test/java/com/iluwatar/hexagonal/domain/LotteryTicketTest.java

@@ -27,6 +27,7 @@ import org.junit.jupiter.api.Test;
 
 import java.util.Arrays;
 import java.util.HashSet;
+import java.util.Set;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertNotEquals;
@@ -39,14 +40,14 @@ class LotteryTicketTest {
   @Test
   void testEquals() {
     PlayerDetails details1 = new PlayerDetails("bob@foo.bar", "1212-121212", "+34332322");
-    LotteryNumbers numbers1 = LotteryNumbers.create(new HashSet<>(Arrays.asList(1, 2, 3, 4)));
+    LotteryNumbers numbers1 = LotteryNumbers.create(Set.of(1, 2, 3, 4));
     LotteryTicket ticket1 = new LotteryTicket(new LotteryTicketId(), details1, numbers1);
     PlayerDetails details2 = new PlayerDetails("bob@foo.bar", "1212-121212", "+34332322");
-    LotteryNumbers numbers2 = LotteryNumbers.create(new HashSet<>(Arrays.asList(1, 2, 3, 4)));
+    LotteryNumbers numbers2 = LotteryNumbers.create(Set.of(1, 2, 3, 4));
     LotteryTicket ticket2 = new LotteryTicket(new LotteryTicketId(), details2, numbers2);
     assertEquals(ticket1, ticket2);
     PlayerDetails details3 = new PlayerDetails("elsa@foo.bar", "1223-121212", "+49332322");
-    LotteryNumbers numbers3 = LotteryNumbers.create(new HashSet<>(Arrays.asList(1, 2, 3, 8)));
+    LotteryNumbers numbers3 = LotteryNumbers.create(Set.of(1, 2, 3, 8));
     LotteryTicket ticket3 = new LotteryTicket(new LotteryTicketId(), details3, numbers3);
     assertNotEquals(ticket1, ticket3);
   }

hexagonal/src/test/java/com/iluwatar/hexagonal/test/LotteryTestUtils.java

@@ -43,7 +43,7 @@ public class LotteryTestUtils {
    * @return lottery ticket
    */
   public static LotteryTicket createLotteryTicket() {
-    return createLotteryTicket("foo@bar.com", "12231-213132", "+99324554", new HashSet<>(Arrays.asList(1, 2, 3, 4)));
+    return createLotteryTicket("foo@bar.com", "12231-213132", "+99324554", Set.of(1, 2, 3, 4));
   }
   
   /**

iterator/src/main/java/com/iluwatar/iterator/list/TreasureChest.java

@@ -40,17 +40,17 @@ public class TreasureChest {
    * Constructor
    */
   public TreasureChest() {
-    items = new ArrayList<>();
+    items = List.of(
-    items.add(new Item(ItemType.POTION, "Potion of courage"));
+            new Item(ItemType.POTION, "Potion of courage"),
-    items.add(new Item(ItemType.RING, "Ring of shadows"));
+            new Item(ItemType.RING, "Ring of shadows"),
-    items.add(new Item(ItemType.POTION, "Potion of wisdom"));
+            new Item(ItemType.POTION, "Potion of wisdom"),
-    items.add(new Item(ItemType.POTION, "Potion of blood"));
+            new Item(ItemType.POTION, "Potion of blood"),
-    items.add(new Item(ItemType.WEAPON, "Sword of silver +1"));
+            new Item(ItemType.WEAPON, "Sword of silver +1"),
-    items.add(new Item(ItemType.POTION, "Potion of rust"));
+            new Item(ItemType.POTION, "Potion of rust"),
-    items.add(new Item(ItemType.POTION, "Potion of healing"));
+            new Item(ItemType.POTION, "Potion of healing"),
-    items.add(new Item(ItemType.RING, "Ring of armor"));
+            new Item(ItemType.RING, "Ring of armor"),
-    items.add(new Item(ItemType.WEAPON, "Steel halberd"));
+            new Item(ItemType.WEAPON, "Steel halberd"),
-    items.add(new Item(ItemType.WEAPON, "Dagger of poison"));
+            new Item(ItemType.WEAPON, "Dagger of poison"));
   }
 
   public Iterator<Item> iterator(ItemType itemType) {

iterator/src/test/java/com/iluwatar/iterator/list/TreasureChestTest.java

@@ -28,7 +28,6 @@ import static org.junit.jupiter.api.Assertions.assertNotNull;
 import static org.junit.jupiter.api.Assertions.fail;
 
 import com.iluwatar.iterator.Iterator;
-import java.util.ArrayList;
 import java.util.List;
 import org.junit.jupiter.params.ParameterizedTest;
 import org.junit.jupiter.params.provider.MethodSource;
@@ -46,18 +45,18 @@ public class TreasureChestTest {
    * @return The set of all expected items in the chest
    */
   public static List<Object[]> dataProvider() {
-    final List<Object[]> parameters = new ArrayList<>();
+    return List.of(
-    parameters.add(new Object[]{new Item(ItemType.POTION, "Potion of courage")});
+            new Object[]{new Item(ItemType.POTION, "Potion of courage")},
-    parameters.add(new Object[]{new Item(ItemType.RING, "Ring of shadows")});
+            new Object[]{new Item(ItemType.RING, "Ring of shadows")},
-    parameters.add(new Object[]{new Item(ItemType.POTION, "Potion of wisdom")});
+            new Object[]{new Item(ItemType.POTION, "Potion of wisdom")},
-    parameters.add(new Object[]{new Item(ItemType.POTION, "Potion of blood")});
+            new Object[]{new Item(ItemType.POTION, "Potion of blood")},
-    parameters.add(new Object[]{new Item(ItemType.WEAPON, "Sword of silver +1")});
+            new Object[]{new Item(ItemType.WEAPON, "Sword of silver +1")},
-    parameters.add(new Object[]{new Item(ItemType.POTION, "Potion of rust")});
+            new Object[]{new Item(ItemType.POTION, "Potion of rust")},
-    parameters.add(new Object[]{new Item(ItemType.POTION, "Potion of healing")});
+            new Object[]{new Item(ItemType.POTION, "Potion of healing")},
-    parameters.add(new Object[]{new Item(ItemType.RING, "Ring of armor")});
+            new Object[]{new Item(ItemType.RING, "Ring of armor")},
-    parameters.add(new Object[]{new Item(ItemType.WEAPON, "Steel halberd")});
+            new Object[]{new Item(ItemType.WEAPON, "Steel halberd")},
-    parameters.add(new Object[]{new Item(ItemType.WEAPON, "Dagger of poison")});
+            new Object[]{new Item(ItemType.WEAPON, "Dagger of poison")}
-    return parameters;
+    );
   }
 
   /**

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

@@ -66,11 +66,10 @@ public class CakeTest {
     assertNotNull(cake.getLayers());
     assertTrue(cake.getLayers().isEmpty());
 
-    final Set<CakeLayer> expectedLayers = new HashSet<>();
+    final Set<CakeLayer> expectedLayers = Set.of(
-    expectedLayers.add(new CakeLayer("layer1", 1000));
+            new CakeLayer("layer1", 1000),
-    expectedLayers.add(new CakeLayer("layer2", 2000));
+            new CakeLayer("layer2", 2000),
-    expectedLayers.add(new CakeLayer("layer3", 3000));
+            new CakeLayer("layer3", 3000));
-
     cake.setLayers(expectedLayers);
     assertEquals(expectedLayers, cake.getLayers());
   }
@@ -111,7 +110,7 @@ public class CakeTest {
     cake.setTopping(topping);
     cake.addLayer(layer);
 
-    final String expected = "id=1234 topping=id=2345 name=topping calories=20 " 
+    final String 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/CakeViewImplTest.java

@@ -31,7 +31,6 @@ import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 import org.slf4j.LoggerFactory;
 
-import java.util.ArrayList;
 import java.util.LinkedList;
 import java.util.List;
 
@@ -64,14 +63,13 @@ public class CakeViewImplTest {
   @Test
   public void testRender() {
 
-    final List<CakeLayerInfo> layers = new ArrayList<>();
+    final List<CakeLayerInfo> layers = List.of(
-    layers.add(new CakeLayerInfo("layer1", 1000));
+            new CakeLayerInfo("layer1", 1000),
-    layers.add(new CakeLayerInfo("layer2", 2000));
+            new CakeLayerInfo("layer2", 2000),
-    layers.add(new CakeLayerInfo("layer3", 3000));
+            new CakeLayerInfo("layer3", 3000));
 
-    final List<CakeInfo> cakes = new ArrayList<>();
     final CakeInfo cake = new CakeInfo(new CakeToppingInfo("topping", 1000), layers);
-    cakes.add(cake);
+    final List<CakeInfo> cakes = List.of(cake);
 
     final CakeBakingService bakingService = mock(CakeBakingService.class);
     when(bakingService.getAllCakes()).thenReturn(cakes);

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

@@ -24,12 +24,9 @@
 package com.iluwatar.leaderelection.bully;
 
 import com.iluwatar.leaderelection.*;
-import com.iluwatar.leaderelection.ring.RingInstance;
-import com.iluwatar.leaderelection.ring.RingMessageManager;
 import org.junit.jupiter.api.Test;
 
 import java.lang.reflect.Field;
-import java.util.HashMap;
 import java.util.Map;
 import java.util.Queue;
 
@@ -43,8 +40,7 @@ public class BullyMessageManagerTest {
   @Test
   public void testSendHeartbeatMessage() {
     Instance instance1 = new BullyInstance(null, 1, 1);
-    Map<Integer, Instance> instanceMap = new HashMap<>();
+    Map<Integer, Instance> instanceMap = Map.of(1, instance1);
-    instanceMap.put(1, instance1);
     MessageManager messageManager = new BullyMessageManager(instanceMap);
     assertTrue(messageManager.sendHeartbeatMessage(1));
   }
@@ -56,11 +52,7 @@ public class BullyMessageManagerTest {
       Instance instance2 = new BullyInstance(null, 1, 2);
       Instance instance3 = new BullyInstance(null, 1, 3);
       Instance instance4 = new BullyInstance(null, 1, 4);
-      Map<Integer, Instance> instanceMap = new HashMap<>();
+      Map<Integer, Instance> instanceMap = Map.of(1, instance1, 2, instance2, 3, instance3, 4, instance4);
-      instanceMap.put(1, instance1);
-      instanceMap.put(2, instance2);
-      instanceMap.put(3, instance3);
-      instanceMap.put(4, instance4);
       instance1.setAlive(false);
       MessageManager messageManager = new BullyMessageManager(instanceMap);
       boolean result = messageManager.sendElectionMessage(3, "3");
@@ -84,11 +76,7 @@ public class BullyMessageManagerTest {
     Instance instance2 = new BullyInstance(null, 1, 2);
     Instance instance3 = new BullyInstance(null, 1, 3);
     Instance instance4 = new BullyInstance(null, 1, 4);
-    Map<Integer, Instance> instanceMap = new HashMap<>();
+    Map<Integer, Instance> instanceMap = Map.of(1, instance1, 2, instance2, 3, instance3, 4, instance4);
-    instanceMap.put(1, instance1);
-    instanceMap.put(2, instance2);
-    instanceMap.put(3, instance3);
-    instanceMap.put(4, instance4);
     instance1.setAlive(false);
     MessageManager messageManager = new BullyMessageManager(instanceMap);
     boolean result = messageManager.sendElectionMessage(2, "2");
@@ -102,11 +90,7 @@ public class BullyMessageManagerTest {
       Instance instance2 = new BullyInstance(null, 1, 2);
       Instance instance3 = new BullyInstance(null, 1, 3);
       Instance instance4 = new BullyInstance(null, 1, 4);
-      Map<Integer, Instance> instanceMap = new HashMap<>();
+      Map<Integer, Instance> instanceMap = Map.of(1, instance1, 2, instance2, 3, instance3, 4, instance4);
-      instanceMap.put(1, instance1);
-      instanceMap.put(2, instance2);
-      instanceMap.put(3, instance3);
-      instanceMap.put(4, instance4);
       instance1.setAlive(false);
       MessageManager messageManager = new BullyMessageManager(instanceMap);
       messageManager.sendLeaderMessage(2, 2);
@@ -129,10 +113,7 @@ public class BullyMessageManagerTest {
       Instance instance1 = new BullyInstance(null, 1, 1);
       Instance instance2 = new BullyInstance(null, 1, 2);
       Instance instance3 = new BullyInstance(null, 1, 3);
-      Map<Integer, Instance> instanceMap = new HashMap<>();
+      Map<Integer, Instance> instanceMap = Map.of(1, instance1, 2, instance2, 3, instance3);
-      instanceMap.put(1, instance1);
-      instanceMap.put(2, instance2);
-      instanceMap.put(3, instance3);
       MessageManager messageManager = new BullyMessageManager(instanceMap);
       messageManager.sendHeartbeatInvokeMessage(2);
       Message message = new Message(MessageType.HEARTBEAT_INVOKE, "");

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

@@ -27,7 +27,6 @@ import com.iluwatar.leaderelection.*;
 import org.junit.jupiter.api.Test;
 
 import java.lang.reflect.Field;
-import java.util.HashMap;
 import java.util.Map;
 import java.util.Queue;
 
@@ -41,8 +40,7 @@ public class RingMessageManagerTest {
   @Test
   public void testSendHeartbeatMessage() {
     Instance instance1 = new RingInstance(null, 1, 1);
-    Map<Integer, Instance> instanceMap = new HashMap<>();
+    Map<Integer, Instance> instanceMap = Map.of(1, instance1);
-    instanceMap.put(1, instance1);
     MessageManager messageManager = new RingMessageManager(instanceMap);
     assertTrue(messageManager.sendHeartbeatMessage(1));
   }
@@ -53,10 +51,7 @@ public class RingMessageManagerTest {
       Instance instance1 = new RingInstance(null, 1, 1);
       Instance instance2 = new RingInstance(null, 1, 2);
       Instance instance3 = new RingInstance(null, 1, 3);
-      Map<Integer, Instance> instanceMap = new HashMap<>();
+      Map<Integer, Instance> instanceMap = Map.of(1, instance1, 2, instance2, 3, instance3);
-      instanceMap.put(1, instance1);
-      instanceMap.put(2, instance2);
-      instanceMap.put(3, instance3);
       MessageManager messageManager = new RingMessageManager(instanceMap);
       String messageContent = "2";
       messageManager.sendElectionMessage(2, messageContent);
@@ -78,10 +73,7 @@ public class RingMessageManagerTest {
       Instance instance1 = new RingInstance(null, 1, 1);
       Instance instance2 = new RingInstance(null, 1, 2);
       Instance instance3 = new RingInstance(null, 1, 3);
-      Map<Integer, Instance> instanceMap = new HashMap<>();
+      Map<Integer, Instance> instanceMap = Map.of(1, instance1, 2, instance2, 3, instance3);
-      instanceMap.put(1, instance1);
-      instanceMap.put(2, instance2);
-      instanceMap.put(3, instance3);
       MessageManager messageManager = new RingMessageManager(instanceMap);
       String messageContent = "3";
       messageManager.sendLeaderMessage(2, 3);
@@ -102,10 +94,7 @@ public class RingMessageManagerTest {
       Instance instance1 = new RingInstance(null, 1, 1);
       Instance instance2 = new RingInstance(null, 1, 2);
       Instance instance3 = new RingInstance(null, 1, 3);
-      Map<Integer, Instance> instanceMap = new HashMap<>();
+      Map<Integer, Instance> instanceMap = Map.of(1, instance1, 2, instance2, 3, instance3);
-      instanceMap.put(1, instance1);
-      instanceMap.put(2, instance2);
-      instanceMap.put(3, instance3);
       MessageManager messageManager = new RingMessageManager(instanceMap);
       messageManager.sendHeartbeatInvokeMessage(2);
       Message ringMessage = new Message(MessageType.HEARTBEAT_INVOKE, "");