Java 11 migration: patterns (remaining b-c) (iluwatar#1081)

* Moves business-delegate pattern  to java 11

* Moves bytecode pattern  to java 11

* Moves caching pattern  to java 11

* Moves callback pattern  to java 11

* Moves chain pattern  to java 11

* Moves circuit-breaker pattern  to java 11

* Moves collection-pipeline pattern  to java 11

* Moves command pattern  to java 11

* Moves commander pattern  to java 11

* Moves composite pattern  to java 11

* Corrects test cases

business-delegate/src/main/java/com/iluwatar/business/delegate/App.java

@@ -46,15 +46,15 @@ public class App {
    */
   public static void main(String[] args) {
 
-    BusinessDelegate businessDelegate = new BusinessDelegate();
-    BusinessLookup businessLookup = new BusinessLookup();
+    var businessDelegate = new BusinessDelegate();
+    var businessLookup = new BusinessLookup();
     businessLookup.setEjbService(new EjbService());
     businessLookup.setJmsService(new JmsService());
 
     businessDelegate.setLookupService(businessLookup);
     businessDelegate.setServiceType(ServiceType.EJB);
 
-    Client client = new Client(businessDelegate);
+    var client = new Client(businessDelegate);
     client.doTask();
 
     businessDelegate.setServiceType(ServiceType.JMS);

business-delegate/src/test/java/com/iluwatar/business/delegate/BusinessDelegateTest.java

@@ -76,7 +76,7 @@ public void setup() {
   public void testBusinessDelegate() {
 
     // setup a client object
-    Client client = new Client(businessDelegate);
+    var client = new Client(businessDelegate);
 
     // set the service type
     businessDelegate.setServiceType(ServiceType.EJB);

bytecode/src/main/java/com/iluwatar/bytecode/App.java

@@ -24,7 +24,6 @@
 package com.iluwatar.bytecode;
 
 import com.iluwatar.bytecode.util.InstructionConverterUtil;
-import java.util.Stack;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -51,12 +50,12 @@ public class App {
    */
   public static void main(String[] args) {
 
-    Wizard wizard = new Wizard();
+    var wizard = new Wizard();
     wizard.setHealth(45);
     wizard.setAgility(7);
     wizard.setWisdom(11);
 
-    VirtualMachine vm = new VirtualMachine();
+    var vm = new VirtualMachine();
     vm.getWizards()[0] = wizard;
 
     interpretInstruction("LITERAL 0", vm);
@@ -74,9 +73,8 @@ public static void main(String[] args) {
   }
 
   private static void interpretInstruction(String instruction, VirtualMachine vm) {
-    InstructionConverterUtil converter = new InstructionConverterUtil();
-    vm.execute(converter.convertToByteCode(instruction));
-    Stack<Integer> stack = vm.getStack();
+    vm.execute(InstructionConverterUtil.convertToByteCode(instruction));
+    var stack = vm.getStack();
     LOGGER.info(instruction + String.format("%" + (12 - instruction.length()) + "s", "") + stack);
   }
 }

bytecode/src/main/java/com/iluwatar/bytecode/Instruction.java

@@ -40,7 +40,7 @@ public enum Instruction {
   ADD(10),
   DIVIDE(11);
 
-  private int value;
+  private final int value;
 
   Instruction(int value) {
     this.value = value;
@@ -57,7 +57,7 @@ public int getIntValue() {
    * @return representation of the instruction
    */
   public static Instruction getInstruction(int value) {
-    for (int i = 0; i < Instruction.values().length; i++) {
+    for (var i = 0; i < Instruction.values().length; i++) {
       if (Instruction.values()[i].getIntValue() == value) {
         return Instruction.values()[i];
       }

bytecode/src/main/java/com/iluwatar/bytecode/VirtualMachine.java

@@ -30,15 +30,15 @@
  */
 public class VirtualMachine {
 
-  private Stack<Integer> stack = new Stack();
+  private Stack<Integer> stack = new Stack<>();
 
   private Wizard[] wizards = new Wizard[2];
 
   /**
    * Constructor.
    */
   public VirtualMachine() {
-    for (int i = 0; i < wizards.length; i++) {
+    for (var i = 0; i < wizards.length; i++) {
       wizards[i] = new Wizard();
     }
   }
@@ -49,19 +49,17 @@ public VirtualMachine() {
    * @param bytecode to execute
    */
   public void execute(int[] bytecode) {
-    for (int i = 0; i < bytecode.length; i++) {
+    for (var i = 0; i < bytecode.length; i++) {
       Instruction instruction = Instruction.getInstruction(bytecode[i]);
-      int wizard;
-      int amount;
       switch (instruction) {
         case LITERAL:
           // Read the next byte from the bytecode.
           int value = bytecode[++i];
           stack.push(value);
           break;
         case SET_AGILITY:
-          amount = stack.pop();
-          wizard = stack.pop();
+          var amount = stack.pop();
+          var wizard = stack.pop();
           setAgility(wizard, amount);
           break;
         case SET_WISDOM:
@@ -87,8 +85,8 @@ public void execute(int[] bytecode) {
           stack.push(getWisdom(wizard));
           break;
         case ADD:
-          int a = stack.pop();
-          int b = stack.pop();
+          var a = stack.pop();
+          var b = stack.pop();
           stack.push(a + b);
           break;
         case DIVIDE:

bytecode/src/main/java/com/iluwatar/bytecode/util/InstructionConverterUtil.java

@@ -40,15 +40,15 @@ public static int[] convertToByteCode(String instructions) {
       return new int[0];
     }
 
-    String[] splitedInstructions = instructions.trim().split(" ");
-    int[] bytecode = new int[splitedInstructions.length];
-    for (int i = 0; i < splitedInstructions.length; i++) {
+    var splitedInstructions = instructions.trim().split(" ");
+    var bytecode = new int[splitedInstructions.length];
+    for (var i = 0; i < splitedInstructions.length; i++) {
       if (isValidInstruction(splitedInstructions[i])) {
         bytecode[i] = Instruction.valueOf(splitedInstructions[i]).getIntValue();
       } else if (isValidInt(splitedInstructions[i])) {
-        bytecode[i] = Integer.valueOf(splitedInstructions[i]);
+        bytecode[i] = Integer.parseInt(splitedInstructions[i]);
       } else {
-        String errorMessage = "Invalid instruction or number: " + splitedInstructions[i];
+        var errorMessage = "Invalid instruction or number: " + splitedInstructions[i];
         throw new IllegalArgumentException(errorMessage);
       }
     }

bytecode/src/test/java/com/iluwatar/bytecode/AppTest.java

@@ -32,7 +32,6 @@ public class AppTest {
 
   @Test
   public void test() {
-    String[] args = {};
-    App.main(args);
+    App.main(new String[]{});
   }
 }

bytecode/src/test/java/com/iluwatar/bytecode/VirtualMachineTest.java

@@ -36,11 +36,11 @@ public class VirtualMachineTest {
 
   @Test
   public void testLiteral() {
-    int[] bytecode = new int[2];
+    var bytecode = new int[2];
     bytecode[0] = LITERAL.getIntValue();
     bytecode[1] = 10;
 
-    VirtualMachine vm = new VirtualMachine();
+    var vm = new VirtualMachine();
     vm.execute(bytecode);
 
     assertEquals(1, vm.getStack().size());
@@ -49,56 +49,56 @@ public void testLiteral() {
 
   @Test
   public void testSetHealth() {
-    int wizardNumber = 0;
-    int[] bytecode = new int[5];
+    var wizardNumber = 0;
+    var bytecode = new int[5];
     bytecode[0] = LITERAL.getIntValue();
     bytecode[1] = wizardNumber;
     bytecode[2] = LITERAL.getIntValue();
     bytecode[3] = 50;                        // health amount
     bytecode[4] = SET_HEALTH.getIntValue();
 
-    VirtualMachine vm = new VirtualMachine();
+    var vm = new VirtualMachine();
     vm.execute(bytecode);
 
     assertEquals(50, vm.getWizards()[wizardNumber].getHealth());
   }
 
   @Test
   public void testSetAgility() {
-    int wizardNumber = 0;
-    int[] bytecode = new int[5];
+    var wizardNumber = 0;
+    var bytecode = new int[5];
     bytecode[0] = LITERAL.getIntValue();
     bytecode[1] = wizardNumber;
     bytecode[2] = LITERAL.getIntValue();
     bytecode[3] = 50;                        // agility amount
     bytecode[4] = SET_AGILITY.getIntValue();
 
-    VirtualMachine vm = new VirtualMachine();
+    var vm = new VirtualMachine();
     vm.execute(bytecode);
 
     assertEquals(50, vm.getWizards()[wizardNumber].getAgility());
   }
 
   @Test
   public void testSetWisdom() {
-    int wizardNumber = 0;
-    int[] bytecode = new int[5];
+    var wizardNumber = 0;
+    var bytecode = new int[5];
     bytecode[0] = LITERAL.getIntValue();
     bytecode[1] = wizardNumber;
     bytecode[2] = LITERAL.getIntValue();
     bytecode[3] = 50;                        // wisdom amount
     bytecode[4] = SET_WISDOM.getIntValue();
 
-    VirtualMachine vm = new VirtualMachine();
+    var vm = new VirtualMachine();
     vm.execute(bytecode);
 
     assertEquals(50, vm.getWizards()[wizardNumber].getWisdom());
   }
 
   @Test
   public void testGetHealth() {
-    int wizardNumber = 0;
-    int[] bytecode = new int[8];
+    var wizardNumber = 0;
+    var bytecode = new int[8];
     bytecode[0] = LITERAL.getIntValue();
     bytecode[1] = wizardNumber;
     bytecode[2] = LITERAL.getIntValue();
@@ -108,21 +108,21 @@ public void testGetHealth() {
     bytecode[6] = wizardNumber;
     bytecode[7] = GET_HEALTH.getIntValue();
 
-    VirtualMachine vm = new VirtualMachine();
+    var vm = new VirtualMachine();
     vm.execute(bytecode);
 
     assertEquals(Integer.valueOf(50), vm.getStack().pop());
   }
 
   @Test
   public void testPlaySound() {
-    int wizardNumber = 0;
-    int[] bytecode = new int[3];
+    var wizardNumber = 0;
+    var bytecode = new int[3];
     bytecode[0] = LITERAL.getIntValue();
     bytecode[1] = wizardNumber;
     bytecode[2] = PLAY_SOUND.getIntValue();
 
-    VirtualMachine vm = new VirtualMachine();
+    var vm = new VirtualMachine();
     vm.execute(bytecode);
 
     assertEquals(0, vm.getStack().size());
@@ -131,13 +131,13 @@ public void testPlaySound() {
 
   @Test
   public void testSpawnParticles() {
-    int wizardNumber = 0;
-    int[] bytecode = new int[3];
+    var wizardNumber = 0;
+    var bytecode = new int[3];
     bytecode[0] = LITERAL.getIntValue();
     bytecode[1] = wizardNumber;
     bytecode[2] = SPAWN_PARTICLES.getIntValue();
 
-    VirtualMachine vm = new VirtualMachine();
+    var vm = new VirtualMachine();
     vm.execute(bytecode);
 
     assertEquals(0, vm.getStack().size());
@@ -146,9 +146,9 @@ public void testSpawnParticles() {
 
   @Test
   public void testInvalidInstruction() {
-    int[] bytecode = new int[1];
+    var bytecode = new int[1];
     bytecode[0] = 999;
-    VirtualMachine vm = new VirtualMachine();
+    var vm = new VirtualMachine();
 
     assertThrows(IllegalArgumentException.class, () -> vm.execute(bytecode));
   }

bytecode/src/test/java/com/iluwatar/bytecode/util/InstructionConverterUtilTest.java

@@ -34,19 +34,19 @@
 public class InstructionConverterUtilTest {
   @Test
   public void testEmptyInstruction() {
-    String instruction = "";
+    var instruction = "";
 
-    int[] bytecode = InstructionConverterUtil.convertToByteCode(instruction);
+    var bytecode = InstructionConverterUtil.convertToByteCode(instruction);
 
     Assertions.assertEquals(0, bytecode.length);
   }
 
   @Test
   public void testInstructions() {
-    String instructions =
-        "LITERAL 35 SET_HEALTH SET_WISDOM SET_AGILITY PLAY_SOUND SPAWN_PARTICLES GET_HEALTH ADD DIVIDE";
+    var instructions = "LITERAL 35 SET_HEALTH SET_WISDOM SET_AGILITY PLAY_SOUND"
+        + " SPAWN_PARTICLES GET_HEALTH ADD DIVIDE";
 
-    int[] bytecode = InstructionConverterUtil.convertToByteCode(instructions);
+    var bytecode = InstructionConverterUtil.convertToByteCode(instructions);
 
     Assertions.assertEquals(10, bytecode.length);
     Assertions.assertEquals(Instruction.LITERAL.getIntValue(), bytecode[0]);

caching/src/main/java/com/iluwatar/caching/App.java

@@ -76,7 +76,7 @@ public static void main(String[] args) {
     // true to run the tests with MongoDB (provided that MongoDB is
     // installed and socket connection is open).
     AppManager.initCacheCapacity(3);
-    App app = new App();
+    var app = new App();
     app.useReadAndWriteThroughStrategy();
     app.useReadThroughAndWriteAroundStrategy();
     app.useReadThroughAndWriteBehindStrategy();
@@ -90,7 +90,7 @@ public void useReadAndWriteThroughStrategy() {
     LOGGER.info("# CachingPolicy.THROUGH");
     AppManager.initCachingPolicy(CachingPolicy.THROUGH);
 
-    UserAccount userAccount1 = new UserAccount("001", "John", "He is a boy.");
+    var userAccount1 = new UserAccount("001", "John", "He is a boy.");
 
     AppManager.save(userAccount1);
     LOGGER.info(AppManager.printCacheContent());
@@ -105,7 +105,7 @@ public void useReadThroughAndWriteAroundStrategy() {
     LOGGER.info("# CachingPolicy.AROUND");
     AppManager.initCachingPolicy(CachingPolicy.AROUND);
 
-    UserAccount userAccount2 = new UserAccount("002", "Jane", "She is a girl.");
+    var userAccount2 = new UserAccount("002", "Jane", "She is a girl.");
 
     AppManager.save(userAccount2);
     LOGGER.info(AppManager.printCacheContent());
@@ -127,9 +127,9 @@ public void useReadThroughAndWriteBehindStrategy() {
     LOGGER.info("# CachingPolicy.BEHIND");
     AppManager.initCachingPolicy(CachingPolicy.BEHIND);
 
-    UserAccount userAccount3 = new UserAccount("003", "Adam", "He likes food.");
-    UserAccount userAccount4 = new UserAccount("004", "Rita", "She hates cats.");
-    UserAccount userAccount5 = new UserAccount("005", "Isaac", "He is allergic to mustard.");
+    var userAccount3 = new UserAccount("003", "Adam", "He likes food.");
+    var userAccount4 = new UserAccount("004", "Rita", "She hates cats.");
+    var userAccount5 = new UserAccount("005", "Isaac", "He is allergic to mustard.");
 
     AppManager.save(userAccount3);
     AppManager.save(userAccount4);
@@ -152,9 +152,9 @@ public void useCacheAsideStategy() {
     AppManager.initCachingPolicy(CachingPolicy.ASIDE);
     LOGGER.info(AppManager.printCacheContent());
 
-    UserAccount userAccount3 = new UserAccount("003", "Adam", "He likes food.");
-    UserAccount userAccount4 = new UserAccount("004", "Rita", "She hates cats.");
-    UserAccount userAccount5 = new UserAccount("005", "Isaac", "He is allergic to mustard.");
+    var userAccount3 = new UserAccount("003", "Adam", "He likes food.");
+    var userAccount4 = new UserAccount("004", "Rita", "She hates cats.");
+    var userAccount5 = new UserAccount("005", "Isaac", "He is allergic to mustard.");
     AppManager.save(userAccount3);
     AppManager.save(userAccount4);
     AppManager.save(userAccount5);