Merge pull request #1479 from anuragagarwal561994/java-11

Java 11 remaining pattern

naked-objects/dom/pom.xml

@@ -127,7 +127,7 @@
 												</goals>
 											</pluginExecutionFilter>
 											<action>
-												<ignore></ignore>
+												<ignore/>
 											</action>
 										</pluginExecution>
 									</pluginExecutions>

naked-objects/dom/src/main/java/domainapp/dom/app/homepage/HomePageViewModel.layout.json

-/**
- *  Licensed to the Apache Software Foundation (ASF) under one or more
- *  contributor license agreements.  See the NOTICE file distributed with
- *  this work for additional information regarding copyright ownership.
- *  The ASF licenses this file to You under the Apache License, Version 2.0
- *  (the "License"); you may not use this file except in compliance with
- *  the License.  You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- *  Unless required by applicable law or agreed to in writing, software
- *  distributed under the License is distributed on an "AS IS" BASIS,
- *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- *  See the License for the specific language governing permissions and
- *  limitations under the License.
- */
 {
   "columns": [
     {

naked-objects/dom/src/main/java/domainapp/dom/modules/simple/SimpleObject.java

@@ -50,9 +50,9 @@ import org.apache.isis.applib.util.ObjectContracts;
     strategy = javax.jdo.annotations.IdGeneratorStrategy.IDENTITY, column = "id")
 @javax.jdo.annotations.Version(strategy = VersionStrategy.VERSION_NUMBER, column = "version")
 @javax.jdo.annotations.Queries({
-    @javax.jdo.annotations.Query(name = "find", language = "JDOQL", value = "SELECT "
+    @javax.jdo.annotations.Query(name = "find", value = "SELECT "
         + "FROM domainapp.dom.modules.simple.SimpleObject "),
-    @javax.jdo.annotations.Query(name = "findByName", language = "JDOQL", value = "SELECT "
+    @javax.jdo.annotations.Query(name = "findByName", value = "SELECT "
         + "FROM domainapp.dom.modules.simple.SimpleObject " + "WHERE name.indexOf(:name) >= 0 ")})
 @javax.jdo.annotations.Unique(name = "SimpleObject_name_UNQ", members = {"name"})
 @DomainObject

naked-objects/dom/src/main/java/domainapp/dom/modules/simple/SimpleObject.layout.json

-/**
- *  Licensed to the Apache Software Foundation (ASF) under one or more
- *  contributor license agreements.  See the NOTICE file distributed with
- *  this work for additional information regarding copyright ownership.
- *  The ASF licenses this file to You under the Apache License, Version 2.0
- *  (the "License"); you may not use this file except in compliance with
- *  the License.  You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- *  Unless required by applicable law or agreed to in writing, software
- *  distributed under the License is distributed on an "AS IS" BASIS,
- *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- *  See the License for the specific language governing permissions and
- *  limitations under the License.
- */
 {
   "columns": [
     {

naked-objects/dom/src/test/java/domainapp/dom/modules/simple/SimpleObjectTest.java

@@ -37,12 +37,12 @@ public class SimpleObjectTest {
   SimpleObject simpleObject;
 
   @Before
-  public void setUp() throws Exception {
+  public void setUp() {
     simpleObject = new SimpleObject();
   }
   
   @Test
-  public void testName() throws Exception {
+  public void testName() {
     // given
     String name = "Foobar";
     assertNull(simpleObject.getName());

naked-objects/dom/src/test/java/domainapp/dom/modules/simple/SimpleObjectsTest.java

@@ -52,13 +52,13 @@ public class SimpleObjectsTest {
   SimpleObjects simpleObjects;
 
   @Before
-  public void setUp() throws Exception {
+  public void setUp() {
     simpleObjects = new SimpleObjects();
     simpleObjects.container = mockContainer;
   }
   
   @Test
-  public void testCreate() throws Exception {
+  public void testCreate() {
 
     // given
     final SimpleObject simpleObject = new SimpleObject();
@@ -85,7 +85,7 @@ public class SimpleObjectsTest {
   }
   
   @Test
-  public void testListAll() throws Exception {
+  public void testListAll() {
 
     // given
     final List<SimpleObject> all = Lists.newArrayList();

naked-objects/fixture/src/main/java/domainapp/fixture/modules/simple/SimpleObjectCreate.java

@@ -67,8 +67,7 @@ public class SimpleObjectCreate extends FixtureScript {
 
   @Override
   protected void execute(final ExecutionContext ec) {
-
-    String paramName = checkParam("name", ec, String.class);
+    var paramName = checkParam("name", ec, String.class);
 
     this.simpleObject = wrap(simpleObjects).create(paramName);
 

naked-objects/fixture/src/main/java/domainapp/fixture/scenarios/RecreateSimpleObjects.java

@@ -27,7 +27,6 @@ import com.google.common.collect.Lists;
 import domainapp.dom.modules.simple.SimpleObject;
 import domainapp.fixture.modules.simple.SimpleObjectCreate;
 import domainapp.fixture.modules.simple.SimpleObjectsTearDown;
-import java.util.Collections;
 import java.util.List;
 import org.apache.isis.applib.fixturescripts.FixtureScript;
 
@@ -37,8 +36,18 @@ import org.apache.isis.applib.fixturescripts.FixtureScript;
  */
 public class RecreateSimpleObjects extends FixtureScript {
 
-  public final List<String> names = Collections.unmodifiableList(List.of("Foo", "Bar", "Baz",
-      "Frodo", "Froyo", "Fizz", "Bip", "Bop", "Bang", "Boo"));
+  public final List<String> names = List.of(
+      "Foo",
+      "Bar",
+      "Baz",
+      "Frodo",
+      "Froyo",
+      "Fizz",
+      "Bip",
+      "Bop",
+      "Bang",
+      "Boo"
+  );
 
   // region > number (optional input)
   private Integer number;
@@ -77,7 +86,7 @@ public class RecreateSimpleObjects extends FixtureScript {
   protected void execute(final ExecutionContext ec) {
 
     // defaults
-    final int paramNumber = defaultParam("number", ec, 3);
+    final var paramNumber = defaultParam("number", ec, 3);
 
     // validate
     if (paramNumber < 0 || paramNumber > names.size()) {
@@ -90,8 +99,8 @@ public class RecreateSimpleObjects extends FixtureScript {
     //
     ec.executeChild(this, new SimpleObjectsTearDown());
 
-    for (int i = 0; i < paramNumber; i++) {
-      final SimpleObjectCreate fs = new SimpleObjectCreate().setName(names.get(i));
+    for (var i = 0; i < paramNumber; i++) {
+      final var fs = new SimpleObjectCreate().setName(names.get(i));
       ec.executeChild(this, fs.getName(), fs);
       simpleObjects.add(fs.getSimpleObject());
     }

naked-objects/integtests/src/test/java/domainapp/integtests/bootstrap/SimpleAppSystemInitializer.java

@@ -40,7 +40,7 @@ public final class SimpleAppSystemInitializer {
    * Init test system
    */
   public static void initIsft() {
-    IsisSystemForTest isft = IsisSystemForTest.getElseNull();
+    var isft = IsisSystemForTest.getElseNull();
     if (isft == null) {
       isft = new SimpleAppSystemBuilder().build().setUpSystem();
       IsisSystemForTest.set(isft);
@@ -58,8 +58,7 @@ public final class SimpleAppSystemInitializer {
     }
 
     private static IsisConfiguration testConfiguration() {
-      final IsisConfigurationForJdoIntegTests testConfiguration =
-          new IsisConfigurationForJdoIntegTests();
+      final var testConfiguration = new IsisConfigurationForJdoIntegTests();
 
       testConfiguration.addRegisterEntitiesPackagePrefix("domainapp.dom.modules");
       return testConfiguration;

naked-objects/integtests/src/test/java/domainapp/integtests/specglue/CatalogOfFixturesGlue.java

@@ -23,10 +23,9 @@
 
 package domainapp.integtests.specglue;
 
-import org.apache.isis.core.specsupport.specs.CukeGlueAbstract;
-
 import cucumber.api.java.Before;
 import domainapp.fixture.scenarios.RecreateSimpleObjects;
+import org.apache.isis.core.specsupport.specs.CukeGlueAbstract;
 
 /**
  * Test Execution to append a fixture of SimpleObjects
@@ -34,7 +33,7 @@ import domainapp.fixture.scenarios.RecreateSimpleObjects;
 public class CatalogOfFixturesGlue extends CukeGlueAbstract {
 
   @Before(value = {"@integration", "@SimpleObjectsFixture"}, order = 20000)
-  public void integrationFixtures() throws Throwable {
+  public void integrationFixtures() {
     scenarioExecution().install(new RecreateSimpleObjects());
   }
 }

naked-objects/integtests/src/test/java/domainapp/integtests/specglue/modules/simple/SimpleObjectGlue.java

@@ -28,9 +28,7 @@ import static org.junit.Assert.assertThat;
 
 import cucumber.api.java.en.Given;
 import cucumber.api.java.en.When;
-import domainapp.dom.modules.simple.SimpleObject;
 import domainapp.dom.modules.simple.SimpleObjects;
-import java.util.List;
 import java.util.UUID;
 import org.apache.isis.core.specsupport.specs.CukeGlueAbstract;
 
@@ -40,9 +38,9 @@ import org.apache.isis.core.specsupport.specs.CukeGlueAbstract;
 public class SimpleObjectGlue extends CukeGlueAbstract {
 
   @Given("^there are.* (\\d+) simple objects$")
-  public void thereAreNumSimpleObjects(int n) throws Throwable {
+  public void thereAreNumSimpleObjects(int n) {
     try {
-      final List<SimpleObject> findAll = service(SimpleObjects.class).listAll();
+      final var findAll = service(SimpleObjects.class).listAll();
       assertThat(findAll.size(), is(n));
       putVar("list", "all", findAll);
 
@@ -52,7 +50,7 @@ public class SimpleObjectGlue extends CukeGlueAbstract {
   }
 
   @When("^I create a new simple object$")
-  public void createNewSimpleObject() throws Throwable {
+  public void createNewSimpleObject() {
     service(SimpleObjects.class).create(UUID.randomUUID().toString());
   }
 

naked-objects/integtests/src/test/java/domainapp/integtests/tests/modules/simple/SimpleObjectIntegTest.java

@@ -26,8 +26,10 @@ package domainapp.integtests.tests.modules.simple;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertNotNull;
 
+import domainapp.dom.modules.simple.SimpleObject;
+import domainapp.fixture.scenarios.RecreateSimpleObjects;
+import domainapp.integtests.tests.SimpleAppIntegTest;
 import javax.inject.Inject;
-
 import org.apache.isis.applib.DomainObjectContainer;
 import org.apache.isis.applib.fixturescripts.FixtureScripts;
 import org.apache.isis.applib.services.wrapper.DisabledException;
@@ -35,10 +37,6 @@ import org.apache.isis.applib.services.wrapper.InvalidException;
 import org.junit.Before;
 import org.junit.Test;
 
-import domainapp.dom.modules.simple.SimpleObject;
-import domainapp.fixture.scenarios.RecreateSimpleObjects;
-import domainapp.integtests.tests.SimpleAppIntegTest;
-
 /**
  * Test Fixtures with Simple Objects
  */
@@ -56,7 +54,7 @@ public class SimpleObjectIntegTest extends SimpleAppIntegTest {
   private static final String NEW_NAME = "new name";
 
   @Before
-  public void setUp() throws Exception {
+  public void setUp() {
     // given
     fs = new RecreateSimpleObjects().setNumber(1);
     fixtureScripts.runFixtureScript(fs, null);
@@ -68,15 +66,15 @@ public class SimpleObjectIntegTest extends SimpleAppIntegTest {
   }
   
   @Test
-  public void testNameAccessible() throws Exception {
-    // when
-    final String name = simpleObjectWrapped.getName();
+  public void testNameAccessible() {
+    /* when */
+    final var name = simpleObjectWrapped.getName();
     // then
     assertEquals(fs.names.get(0), name);
   }
   
   @Test
-  public void testNameCannotBeUpdatedDirectly() throws Exception {
+  public void testNameCannotBeUpdatedDirectly() {
 
     // expect
     expectedExceptions.expect(DisabledException.class);
@@ -86,7 +84,7 @@ public class SimpleObjectIntegTest extends SimpleAppIntegTest {
   }
   
   @Test
-  public void testUpdateName() throws Exception {
+  public void testUpdateName() {
 
     // when
     simpleObjectWrapped.updateName(NEW_NAME);
@@ -96,7 +94,7 @@ public class SimpleObjectIntegTest extends SimpleAppIntegTest {
   }
   
   @Test
-  public void testUpdateNameFailsValidation() throws Exception {
+  public void testUpdateNameFailsValidation() {
 
     // expect
     expectedExceptions.expect(InvalidException.class);
@@ -107,13 +105,13 @@ public class SimpleObjectIntegTest extends SimpleAppIntegTest {
   }
   
   @Test
-  public void testInterpolatesName() throws Exception {
+  public void testInterpolatesName() {
 
     // given
-    final String name = simpleObjectWrapped.getName();
+    final var name = simpleObjectWrapped.getName();
 
     // when
-    final String title = container.titleOf(simpleObjectWrapped);
+    final var title = container.titleOf(simpleObjectWrapped);
 
     // then
     assertEquals("Object: " + name, title);

naked-objects/integtests/src/test/java/domainapp/integtests/tests/modules/simple/SimpleObjectsIntegTest.java

@@ -25,11 +25,13 @@ package domainapp.integtests.tests.modules.simple;
 
 import static org.junit.Assert.assertEquals;
 
+import com.google.common.base.Throwables;
+import domainapp.dom.modules.simple.SimpleObjects;
+import domainapp.fixture.modules.simple.SimpleObjectsTearDown;
+import domainapp.fixture.scenarios.RecreateSimpleObjects;
+import domainapp.integtests.tests.SimpleAppIntegTest;
 import java.sql.SQLIntegrityConstraintViolationException;
-import java.util.List;
-
 import javax.inject.Inject;
-
 import org.apache.isis.applib.fixturescripts.FixtureScript;
 import org.apache.isis.applib.fixturescripts.FixtureScripts;
 import org.hamcrest.Description;
@@ -37,14 +39,6 @@ import org.hamcrest.Matcher;
 import org.hamcrest.TypeSafeMatcher;
 import org.junit.Test;
 
-import com.google.common.base.Throwables;
-
-import domainapp.dom.modules.simple.SimpleObject;
-import domainapp.dom.modules.simple.SimpleObjects;
-import domainapp.fixture.modules.simple.SimpleObjectsTearDown;
-import domainapp.fixture.scenarios.RecreateSimpleObjects;
-import domainapp.integtests.tests.SimpleAppIntegTest;
-
 /**
  * Fixture Pattern Integration Test
  */
@@ -56,25 +50,25 @@ public class SimpleObjectsIntegTest extends SimpleAppIntegTest {
   SimpleObjects simpleObjects;
 
   @Test
-  public void testListAll() throws Exception {
+  public void testListAll() {
 
     // given
-    RecreateSimpleObjects fs = new RecreateSimpleObjects();
+    var fs = new RecreateSimpleObjects();
     fixtureScripts.runFixtureScript(fs, null);
     nextTransaction();
 
     // when
-    final List<SimpleObject> all = wrap(simpleObjects).listAll();
+    final var all = wrap(simpleObjects).listAll();
 
     // then
     assertEquals(fs.getSimpleObjects().size(), all.size());
 
-    SimpleObject simpleObject = wrap(all.get(0));
+    var simpleObject = wrap(all.get(0));
     assertEquals(fs.getSimpleObjects().get(0).getName(), simpleObject.getName());
   }
-  
+
   @Test
-  public void testListAllWhenNone() throws Exception {
+  public void testListAllWhenNone() {
 
     // given
     FixtureScript fs = new SimpleObjectsTearDown();
@@ -82,14 +76,14 @@ public class SimpleObjectsIntegTest extends SimpleAppIntegTest {
     nextTransaction();
 
     // when
-    final List<SimpleObject> all = wrap(simpleObjects).listAll();
+    final var all = wrap(simpleObjects).listAll();
 
     // then
     assertEquals(0, all.size());
   }
-  
+
   @Test
-  public void testCreate() throws Exception {
+  public void testCreate() {
 
     // given
     FixtureScript fs = new SimpleObjectsTearDown();
@@ -100,12 +94,12 @@ public class SimpleObjectsIntegTest extends SimpleAppIntegTest {
     wrap(simpleObjects).create("Faz");
 
     // then
-    final List<SimpleObject> all = wrap(simpleObjects).listAll();
+    final var all = wrap(simpleObjects).listAll();
     assertEquals(1, all.size());
   }
-  
+
   @Test
-  public void testCreateWhenAlreadyExists() throws Exception {
+  public void testCreateWhenAlreadyExists() {
 
     // given
     FixtureScript fs = new SimpleObjectsTearDown();
@@ -115,24 +109,22 @@ public class SimpleObjectsIntegTest extends SimpleAppIntegTest {
     nextTransaction();
 
     // then
-    expectedExceptions.expectCause(causalChainContains(SQLIntegrityConstraintViolationException.class));
+    expectedExceptions
+        .expectCause(causalChainContains(SQLIntegrityConstraintViolationException.class));
 
     // when
     wrap(simpleObjects).create("Faz");
     nextTransaction();
   }
-  
+
+  @SuppressWarnings("SameParameterValue")
   private static Matcher<? extends Throwable> causalChainContains(final Class<?> cls) {
-    return new TypeSafeMatcher<Throwable>() {
+    return new TypeSafeMatcher<>() {
       @Override
+      @SuppressWarnings("UnstableApiUsage")
       protected boolean matchesSafely(Throwable item) {
-        final List<Throwable> causalChain = Throwables.getCausalChain(item);
-        for (Throwable throwable : causalChain) {
-          if (cls.isAssignableFrom(throwable.getClass())) {
-            return true;
-          }
-        }
-        return false;
+        final var causalChain = Throwables.getCausalChain(item);
+        return causalChain.stream().map(Throwable::getClass).anyMatch(cls::isAssignableFrom);
       }
 
       @Override

naked-objects/webapp/ide/eclipse/launch/.gitignore

@@ -2,7 +2,3 @@
 /SimpleApp-PROTOTYPE-no-fixtures.launch
 /SimpleApp-PROTOTYPE-with-fixtures.launch
 /SimpleApp-SERVER-no-fixtures.launch
-/SimpleApp-PROTOTYPE-jrebel.launch
-/SimpleApp-PROTOTYPE-no-fixtures.launch
-/SimpleApp-PROTOTYPE-with-fixtures.launch
-/SimpleApp-SERVER-no-fixtures.launch

naked-objects/webapp/pom.xml

@@ -129,7 +129,7 @@
 										</goals>
 									</pluginExecutionFilter>
 									<action>
-										<ignore></ignore>
+										<ignore/>
 									</action>
 								</pluginExecution>
 							</pluginExecutions>

naked-objects/webapp/src/main/java/domainapp/webapp/SimpleApplication.java

@@ -31,18 +31,15 @@ import com.google.inject.name.Names;
 import com.google.inject.util.Modules;
 import com.google.inject.util.Providers;
 import de.agilecoders.wicket.core.Bootstrap;
-import de.agilecoders.wicket.core.settings.IBootstrapSettings;
 import de.agilecoders.wicket.themes.markup.html.bootswatch.BootswatchTheme;
 import de.agilecoders.wicket.themes.markup.html.bootswatch.BootswatchThemeProvider;
 import java.io.IOException;
 import java.io.InputStream;
 import java.nio.charset.Charset;
-import java.util.List;
 import javax.servlet.http.HttpServletRequest;
 import org.apache.isis.viewer.wicket.viewer.IsisWicketApplication;
 import org.apache.isis.viewer.wicket.viewer.integration.wicket.AuthenticatedWebSessionForIsis;
 import org.apache.wicket.Session;
-import org.apache.wicket.request.IRequestParameters;
 import org.apache.wicket.request.Request;
 import org.apache.wicket.request.Response;
 import org.apache.wicket.request.http.WebRequest;
@@ -85,7 +82,7 @@ public class SimpleApplication extends IsisWicketApplication {
   protected void init() {
     super.init();
 
-    IBootstrapSettings settings = Bootstrap.getSettings();
+    var settings = Bootstrap.getSettings();
     settings.setThemeProvider(new BootswatchThemeProvider(BootswatchTheme.Flatly));
   }
 
@@ -96,13 +93,10 @@ public class SimpleApplication extends IsisWicketApplication {
     }
 
     // else demo mode
-    final AuthenticatedWebSessionForIsis s =
-        (AuthenticatedWebSessionForIsis) super.newSession(request, response);
-    IRequestParameters requestParameters = request.getRequestParameters();
-    final org.apache.wicket.util.string.StringValue user =
-        requestParameters.getParameterValue("user");
-    final org.apache.wicket.util.string.StringValue password =
-        requestParameters.getParameterValue("pass");
+    final var s = (AuthenticatedWebSessionForIsis) super.newSession(request, response);
+    var requestParameters = request.getRequestParameters();
+    final var user = requestParameters.getParameterValue("user");
+    final var password = requestParameters.getParameterValue("pass");
     s.signIn(user.toString(), password.toString());
     return s;
   }
@@ -115,7 +109,7 @@ public class SimpleApplication extends IsisWicketApplication {
 
     // else demo mode
     try {
-      String uname = servletRequest.getParameter("user");
+      var uname = servletRequest.getParameter("user");
       if (uname != null) {
         servletRequest.getSession().invalidate();
       }
@@ -127,7 +121,7 @@ public class SimpleApplication extends IsisWicketApplication {
 
   @Override
   protected Module newIsisWicketModule() {
-    final Module isisDefaults = super.newIsisWicketModule();
+    final var isisDefaults = super.newIsisWicketModule();
 
     final Module overrides = new AbstractModule() {
       @Override
@@ -148,11 +142,11 @@ public class SimpleApplication extends IsisWicketApplication {
     return Modules.override(isisDefaults).with(overrides);
   }
 
+  @SuppressWarnings({"UnstableApiUsage", "SameParameterValue"})
   private static String readLines(final Class<?> contextClass, final String resourceName) {
     try {
-      List<String> readLines =
-          Resources.readLines(Resources.getResource(contextClass, resourceName),
-              Charset.defaultCharset());
+      var resource = Resources.getResource(contextClass, resourceName);
+      var readLines = Resources.readLines(resource, Charset.defaultCharset());
       return Joiner.on("\n").join(readLines);
     } catch (IOException e) {
       return "This is a simple app";

naked-objects/webapp/src/main/webapp/about/index.html

@@ -110,8 +110,8 @@ th, td {
                     </p>
                     <p>
                         provides access to a RESTful API conformant with the
-                        <a href="http://restfulobjects.org">Restful Objects</a> spec</td>.  This is part of Apache Isis Core.  The
-                        implementation technology is JBoss RestEasy.
+                        <a href="http://restfulobjects.org">Restful Objects</a> spec. This is part of Apache Isis Core.
+                        The implementation technology is JBoss RestEasy.
                     </p>
                 </li>
             </ul>

null-object/README.md

@@ -141,11 +141,16 @@ public final class NullNode implements Node {
 Then we can construct and traverse the binary tree without errors as follows.
 
 ```java
-    Node root =
-        new NodeImpl("1", new NodeImpl("11", new NodeImpl("111", NullNode.getInstance(),
-            NullNode.getInstance()), NullNode.getInstance()), new NodeImpl("12",
-            NullNode.getInstance(), new NodeImpl("122", NullNode.getInstance(),
-            NullNode.getInstance())));
+    var root = new NodeImpl("1",
+            new NodeImpl("11",
+                new NodeImpl("111", NullNode.getInstance(), NullNode.getInstance()),
+                NullNode.getInstance()
+            ),
+            new NodeImpl("12",
+                NullNode.getInstance(),
+                new NodeImpl("122", NullNode.getInstance(), NullNode.getInstance())
+            )
+        );
     root.walk();
     
     // 1

null-object/src/main/java/com/iluwatar/nullobject/App.java

@@ -37,12 +37,16 @@ public class App {
    * @param args command line args
    */
   public static void main(String[] args) {
-
-    Node root =
-        new NodeImpl("1", new NodeImpl("11", new NodeImpl("111", NullNode.getInstance(),
-            NullNode.getInstance()), NullNode.getInstance()), new NodeImpl("12",
-            NullNode.getInstance(), new NodeImpl("122", NullNode.getInstance(),
-            NullNode.getInstance())));
+    var root = new NodeImpl("1",
+        new NodeImpl("11",
+            new NodeImpl("111", NullNode.getInstance(), NullNode.getInstance()),
+            NullNode.getInstance()
+        ),
+        new NodeImpl("12",
+            NullNode.getInstance(),
+            new NodeImpl("122", NullNode.getInstance(), NullNode.getInstance())
+        )
+    );
 
     root.walk();
   }

null-object/src/test/java/com/iluwatar/nullobject/AppTest.java

@@ -26,15 +26,11 @@ package com.iluwatar.nullobject;
 import org.junit.jupiter.api.Test;
 
 /**
- * 
  * Application test
- *
  */
 public class AppTest {
-
   @Test
   public void test() {
-    String[] args = {};
-    App.main(args);
+    App.main(new String[]{});
   }
 }

null-object/src/test/java/com/iluwatar/nullobject/NullNodeTest.java

@@ -42,14 +42,14 @@ public class NullNodeTest {
    */
   @Test
   public void testGetInstance() {
-    final NullNode instance = NullNode.getInstance();
+    final var instance = NullNode.getInstance();
     assertNotNull(instance);
     assertSame(instance, NullNode.getInstance());
   }
 
   @Test
   public void testFields() {
-    final NullNode node = NullNode.getInstance();
+    final var node = NullNode.getInstance();
     assertEquals(0, node.getTreeSize());
     assertNull(node.getName());
     assertNull(node.getLeft());

null-object/src/test/java/com/iluwatar/nullobject/TreeTest.java

@@ -23,22 +23,21 @@
 
 package com.iluwatar.nullobject;
 
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.junit.jupiter.api.Assertions.assertSame;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
 import ch.qos.logback.classic.Logger;
 import ch.qos.logback.classic.spi.ILoggingEvent;
 import ch.qos.logback.core.AppenderBase;
+import java.util.LinkedList;
+import java.util.List;
 import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 import org.slf4j.LoggerFactory;
 
-import java.util.LinkedList;
-import java.util.List;
-
-import static org.junit.jupiter.api.Assertions.assertEquals;
-import static org.junit.jupiter.api.Assertions.assertNotNull;
-import static org.junit.jupiter.api.Assertions.assertSame;
-import static org.junit.jupiter.api.Assertions.assertTrue;
-
 /**
  * Date: 12/26/15 - 11:44 PM
  *
@@ -75,12 +74,12 @@ public class TreeTest {
   private static final Node TREE_ROOT;
 
   static {
-    final NodeImpl level1B = new NodeImpl("level1_b", NullNode.getInstance(), NullNode.getInstance());
-    final NodeImpl level2B = new NodeImpl("level2_b", NullNode.getInstance(), NullNode.getInstance());
-    final NodeImpl level3A = new NodeImpl("level3_a", NullNode.getInstance(), NullNode.getInstance());
-    final NodeImpl level3B = new NodeImpl("level3_b", NullNode.getInstance(), NullNode.getInstance());
-    final NodeImpl level2A = new NodeImpl("level2_a", level3A, level3B);
-    final NodeImpl level1A = new NodeImpl("level1_a", level2A, level2B);
+    final var level1B = new NodeImpl("level1_b", NullNode.getInstance(), NullNode.getInstance());
+    final var level2B = new NodeImpl("level2_b", NullNode.getInstance(), NullNode.getInstance());
+    final var level3A = new NodeImpl("level3_a", NullNode.getInstance(), NullNode.getInstance());
+    final var level3B = new NodeImpl("level3_b", NullNode.getInstance(), NullNode.getInstance());
+    final var level2A = new NodeImpl("level2_a", level3A, level3B);
+    final var level1A = new NodeImpl("level1_a", level2A, level2B);
     TREE_ROOT = new NodeImpl("root", level1A, level1B);
   }
 
@@ -112,17 +111,17 @@ public class TreeTest {
 
   @Test
   public void testGetLeft() {
-    final Node level1 = TREE_ROOT.getLeft();
+    final var level1 = TREE_ROOT.getLeft();
     assertNotNull(level1);
     assertEquals("level1_a", level1.getName());
     assertEquals(5, level1.getTreeSize());
 
-    final Node level2 = level1.getLeft();
+    final var level2 = level1.getLeft();
     assertNotNull(level2);
     assertEquals("level2_a", level2.getName());
     assertEquals(3, level2.getTreeSize());
 
-    final Node level3 = level2.getLeft();
+    final var level3 = level2.getLeft();
     assertNotNull(level3);
     assertEquals("level3_a", level3.getName());
     assertEquals(1, level3.getTreeSize());
@@ -132,7 +131,7 @@ public class TreeTest {
 
   @Test
   public void testGetRight() {
-    final Node level1 = TREE_ROOT.getRight();
+    final var level1 = TREE_ROOT.getRight();
     assertNotNull(level1);
     assertEquals("level1_b", level1.getName());
     assertEquals(1, level1.getTreeSize());
@@ -140,7 +139,7 @@ public class TreeTest {
     assertSame(NullNode.getInstance(), level1.getLeft());
   }
 
-  private class InMemoryAppender extends AppenderBase<ILoggingEvent> {
+  private static class InMemoryAppender extends AppenderBase<ILoggingEvent> {
     private final List<ILoggingEvent> log = new LinkedList<>();
 
     public InMemoryAppender() {
@@ -154,7 +153,7 @@ public class TreeTest {
     }
 
     public boolean logContains(String message) {
-      return log.stream().anyMatch(event -> event.getMessage().equals(message));
+      return log.stream().map(ILoggingEvent::getMessage).anyMatch(message::equals);
     }
 
     public int getLogSize() {