Merge remote-tracking branch 'Baeldung/master' into active_mq

# Conflicts: # .gitignore # LICENSE # README.md # core-java-modules/README.md # core-java-modules/core-java-11/README.md # core-java-modules/core-java-11/pom.xml # core-java-modules/core-java-8/README.md # core-java-modules/core-java-8/pom.xml # core-java-modules/core-java-8/src/main/resources/logback.xml # core-java-modules/core-java-annotations/README.md # core-java-modules/core-java-annotations/pom.xml # core-java-modules/core-java-collections-2/README.md # core-java-modules/core-java-collections-2/pom.xml # core-java-modules/core-java-collections-3/README.md # core-java-modules/core-java-collections-3/pom.xml # core-java-modules/core-java-collections-conversions-2/README.md # core-java-modules/core-java-collections-conversions-2/pom.xml # core-java-modules/core-java-collections-conversions/README.md # core-java-modules/core-java-collections-conversions/pom.xml # core-java-modules/core-java-collections-list/README.md # core-java-modules/core-java-collections-list/pom.xml # core-java-modules/core-java-collections/pom.xml # core-java-modules/core-java-datetime-conversion/README.md # core-java-modules/core-java-datetime-conversion/pom.xml # core-java-modules/core-java-datetime-conversion/src/test/java/com/baeldung/datetime/ConvertInstantToTimestampUnitTest.java # core-java-modules/core-java-io-2/pom.xml # core-java-modules/core-java-io/README.md # core-java-modules/core-java-io/pom.xml # core-java-modules/core-java-io/src/test/resources/fileTest.txt # core-java-modules/core-java-io/src/test/resources/sampleTextFile.txt # core-java-modules/core-java-lambdas/README.md # core-java-modules/core-java-lambdas/pom.xml # core-java-modules/core-java-serialization/pom.xml # core-java-modules/core-java-streams/README.md # core-java-modules/core-java-streams/pom.xml # core-java-modules/core-java-strings/README.md # core-java-modules/core-java-strings/pom.xml # core-java-modules/core-java-strings/src/test/resources/stringtoolong.txt # core-java-modules/core-java-uuid/README.md # core-java-modules/core-java-uuid/pom.xml # core-java-modules/pom.xml # image-processing/README.md # image-processing/pom.xml # image-processing/src/main/java/com/baeldung/imageprocessing/addingtext/AddText.java # image-processing/src/main/java/com/baeldung/imageprocessing/opencv/CameraStream.java # jackson-modules/jackson-annotations/README.md # jackson-modules/jackson-annotations/pom.xml # jackson-modules/jackson-conversions-2/README.md # jackson-modules/jackson-conversions-2/pom.xml # jackson-modules/jackson-conversions/README.md # jackson-modules/jackson-conversions/pom.xml # jackson-modules/jackson-custom-conversions/README.md # jackson-modules/jackson-custom-conversions/pom.xml # jackson-modules/jackson-custom-conversions/src/test/java/com/baeldung/defaultserializercustomserializer/CallingDefaultSerializerUnitTest.java # jackson-modules/jackson-custom-conversions/src/test/java/com/baeldung/deserialization/CustomDeserializationUnitTest.java # jackson-modules/jackson-exceptions/README.md # jackson-modules/jackson-exceptions/pom.xml # jackson-modules/jackson-exceptions/src/test/java/com/baeldung/exceptions/JacksonExceptionsUnitTest.java # jackson-modules/jackson-exceptions/src/test/java/com/baeldung/mappingexception/JacksonMappingExceptionUnitTest.java # jackson-modules/pom.xml # parent-boot-1/pom.xml # parent-boot-2/pom.xml # parent-boot-3/pom.xml # patterns-modules/design-patterns-architectural/pom.xml # patterns-modules/design-patterns-architectural/src/main/java/com/baeldung/repositoryvsdaopattern/UserDaoImpl.java # patterns-modules/design-patterns-behavioral-2/README.md # patterns-modules/design-patterns-behavioral-2/pom.xml # patterns-modules/design-patterns-creational-2/README.md # patterns-modules/design-patterns-creational-2/pom.xml # patterns-modules/design-patterns-singleton/README.md # patterns-modules/design-patterns-structural/src/main/resources/log4jstructuraldp.properties # patterns-modules/enterprise-patterns/pom.xml # patterns-modules/intercepting-filter/pom.xml # patterns-modules/pom.xml # persistence-modules/activejdbc/pom.xml # persistence-modules/hibernate5/README.md # persistence-modules/hibernate5/pom.xml # persistence-modules/hibernate5/src/main/java/com/baeldung/hibernate/interceptors/CustomInterceptor.java # persistence-modules/hibernate5/src/main/java/com/baeldung/hibernate/interceptors/entity/User.java # persistence-modules/hibernate5/src/main/java/com/baeldung/hibernate/namingstrategy/CustomPhysicalNamingStrategy.java # persistence-modules/hibernate5/src/main/java/com/baeldung/hibernate/persistjson/Customer.java # persistence-modules/hibernate5/src/main/java/com/baeldung/hibernate/persistjson/HashMapConverter.java # persistence-modules/hibernate5/src/main/java/com/baeldung/hibernate/pojo/OrderEntryIdClass.java # persistence-modules/hibernate5/src/main/java/com/baeldung/hibernate/pojo/OrderEntryPK.java # persistence-modules/hibernate5/src/test/java/com/baeldung/hibernate/IdentifiersIntegrationTest.java # persistence-modules/hibernate5/src/test/java/com/baeldung/hibernate/bootstrap/BootstrapAPIIntegrationTest.java # persistence-modules/hibernate5/src/test/java/com/baeldung/hibernate/proxy/HibernateProxyUnitTest.java # persistence-modules/hibernate5/src/test/resources/hibernate-interceptors.properties # persistence-modules/hibernate5/src/test/resources/hibernate-lifecycle.properties # persistence-modules/hibernate5/src/test/resources/hibernate-namingstrategy.properties # persistence-modules/hibernate5/src/test/resources/hibernate-persistjson.properties # persistence-modules/hibernate5/src/test/resources/hibernate.properties # persistence-modules/pom.xml # persistence-modules/spring-data-jpa-crud/pom.xml # persistence-modules/spring-data-jpa-crud/src/main/java/com/baeldung/repository/FruitRepository.java # persistence-modules/spring-data-jpa-repo-2/README.md # persistence-modules/spring-data-jpa-repo-2/pom.xml # persistence-modules/spring-data-jpa-repo-2/src/main/java/com/baeldung/spring/data/persistence/customrepository/model/User.java # persistence-modules/spring-data-jpa-repo-2/src/main/java/com/baeldung/spring/data/persistence/customrepository/repository/CustomUserRepositoryImpl.java # persistence-modules/spring-data-jpa-repo-2/src/main/java/com/baeldung/spring/data/persistence/saveperformance/Book.java # persistence-modules/spring-data-jpa-repo-2/src/main/resources/application.properties # persistence-modules/spring-data-mongodb-reactive/pom.xml # persistence-modules/spring-data-redis/README.md # persistence-modules/spring-data-redis/pom.xml # persistence-modules/spring-data-redis/src/main/java/com/baeldung/spring/data/reactive/redis/config/RedisConfig.java # persistence-modules/spring-data-redis/src/main/java/com/baeldung/spring/data/redis/config/RedisConfig.java # persistence-modules/spring-data-redis/src/main/java/com/baeldung/spring/data/redis/model/Student.java # persistence-modules/spring-data-redis/src/main/java/com/baeldung/spring/data/redis/queue/RedisMessageSubscriber.java # persistence-modules/spring-data-redis/src/test/java/com/baeldung/spring/data/reactive/redis/template/RedisKeyCommandsManualTest.java # persistence-modules/spring-data-redis/src/test/java/com/baeldung/spring/data/reactive/redis/template/RedisTemplateListOpsManualTest.java # persistence-modules/spring-data-redis/src/test/java/com/baeldung/spring/data/reactive/redis/template/RedisTemplateValueOpsManualTest.java # persistence-modules/spring-data-redis/src/test/java/com/baeldung/spring/data/redis/repo/StudentRepositoryManualTest.java # pom.xml # testing-modules/assertion-libraries/README.md # testing-modules/assertion-libraries/pom.xml # testing-modules/junit-5-basics/README.md # testing-modules/junit-5-basics/pom.xml # testing-modules/mockito-2/src/main/java/com/baeldung/nullmatcher/Helper.java # testing-modules/mockito-2/src/main/java/com/baeldung/nullmatcher/Main.java # testing-modules/mockito-2/src/main/java/com/baeldung/wantedbutnotinvocked/Helper.java # testing-modules/mockito-2/src/main/java/com/baeldung/wantedbutnotinvocked/Main.java # testing-modules/mockito-2/src/test/java/com/baeldung/nullmatcher/MainUnitTest.java # testing-modules/mockito-2/src/test/java/com/baeldung/wantedbutnotinvocked/MainUnitTest.java # testing-modules/pom.xml # testing-modules/spring-mockito/pom.xml # web-modules/dropwizard/pom.xml # web-modules/jakarta-ee/README.md # web-modules/jakarta-ee/pom.xml # web-modules/jakarta-ee/src/test/java/com/baeldung/eclipse/krazo/UserControllerUnitTest.java # web-modules/java-lite/pom.xml # web-modules/javax-servlets-2/README.md # web-modules/javax-servlets-2/pom.xml # web-modules/javax-servlets/pom.xml # web-modules/jee-7/pom.xml # web-modules/jooby/pom.xml # web-modules/ninja/pom.xml # web-modules/pom.xml # web-modules/ratpack/pom.xml # web-modules/resteasy/pom.xml # web-modules/restx/pom.xml # web-modules/spark-java/pom.xml # web-modules/vraptor/pom.xml # xml/README.md # xml/pom.xml # xml/src/main/resources/customer-binding.xml # xml/src/main/resources/sax/baeldung.xml # xml/src/test/resources/example_default_parser.xml # xml/src/test/resources/example_dom4j.xml # xml/src/test/resources/example_jaxb.xml # xml/src/test/resources/example_jaxen.xml # xml/src/test/resources/example_jdom.xml # xml/src/test/resources/example_stax.xml # xml/src/test/resources/sax/baeldung.xml # xml/src/test/resources/xml/websites.xml # xml/src/test/resources/xml/xee_attribute.xml
2024-04-30 12:23:19 -04:00
parent c18eb6d2ed 8cabe509a5
commit a51b7b55d9
27985 changed files with 1584039 additions and 0 deletions
@@ -0,0 +1,15 @@
+package com.baledung.billpugh;
+
+public class BillPughSingleton {
+    private BillPughSingleton() {
+
+    }
+
+    private static class SingletonHelper {
+        private static final BillPughSingleton BILL_PUGH_SINGLETON_INSTANCE = new BillPughSingleton();
+    }
+
+    public static BillPughSingleton getInstance() {
+        return SingletonHelper.BILL_PUGH_SINGLETON_INSTANCE;
+    }
+}
@@ -0,0 +1,11 @@
+package com.baledung.billpugh;
+
+public class EagerLoadedSingleton {
+    private static final EagerLoadedSingleton EAGER_LOADED_SINGLETON = new EagerLoadedSingleton();
+    private EagerLoadedSingleton() {
+
+    }
+    public static EagerLoadedSingleton getInstance() {
+        return EAGER_LOADED_SINGLETON;
+    }
+}
@@ -0,0 +1,15 @@
+package com.baledung.billpugh;
+
+public class LazyLoadedSingleton {
+    private static LazyLoadedSingleton lazyLoadedSingletonObj;
+
+    private LazyLoadedSingleton() {
+    }
+
+    public static LazyLoadedSingleton getInstance() {
+        if (null == lazyLoadedSingletonObj) {
+            lazyLoadedSingletonObj = new LazyLoadedSingleton();
+        }
+        return lazyLoadedSingletonObj;
+    }
+}
@@ -0,0 +1,15 @@
+package com.baledung.billpugh;
+
+public class SynchronizedLazyLoadedSingleton {
+    private static SynchronizedLazyLoadedSingleton synchronizedLazyLoadedSingleton;
+
+    private SynchronizedLazyLoadedSingleton() {
+    }
+
+    public static synchronized SynchronizedLazyLoadedSingleton getInstance() {
+        if (null == synchronizedLazyLoadedSingleton) {
+            synchronizedLazyLoadedSingleton = new SynchronizedLazyLoadedSingleton();
+        }
+        return synchronizedLazyLoadedSingleton;
+    }
+}
@@ -0,0 +1,43 @@
+package com.baledung.billpugh;
+
+import org.junit.jupiter.api.Test;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.util.ArrayList;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+import java.util.concurrent.*;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+public class BillPughSingletonUnitTest {
+    Logger logger = LoggerFactory.getLogger(BillPughSingletonUnitTest.class);
+    @Test
+    void givenSynchronizedLazyLoadedImpl_whenCallgetInstance_thenReturnSingleton() {
+        Set<BillPughSingleton> setHoldingSingletonObj = new HashSet<>();
+        List<Future<BillPughSingleton>> futures = new ArrayList<>();
+
+        ExecutorService executorService = Executors.newFixedThreadPool(10);
+        Callable<BillPughSingleton> runnableTask = () -> {
+            logger.info("run called for:" + Thread.currentThread().getName());
+            return BillPughSingleton.getInstance();
+        };
+
+        int count = 0;
+        while(count < 10) {
+            futures.add(executorService.submit(runnableTask));
+            count++;
+        }
+        futures.forEach(e -> {
+            try {
+                setHoldingSingletonObj.add(e.get());
+            } catch (Exception ex) {
+                throw new RuntimeException(ex);
+            }
+        });
+        executorService.shutdown();
+        assertEquals(1, setHoldingSingletonObj.size());
+    }
+}
@@ -0,0 +1,46 @@
+package com.baledung.billpugh;
+
+import org.junit.jupiter.api.Test;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.util.ArrayList;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+import java.util.concurrent.*;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+public class EagerLoadedSingletonUnitTest {
+
+    Logger logger = LoggerFactory.getLogger(EagerLoadedSingletonUnitTest.class);
+
+    @Test
+    void giveEagerLoadedImpl_whenCallgetInstance_thenReturnSingleton() {
+        Set<EagerLoadedSingleton> set = new HashSet<>();
+        List<Future<EagerLoadedSingleton>> futures = new ArrayList<>();
+
+        ExecutorService executorService = Executors.newFixedThreadPool(10);
+        Callable<EagerLoadedSingleton> runnableTask = () -> {
+                logger.info("run called for:" + Thread.currentThread().getName());
+                return EagerLoadedSingleton.getInstance();
+        };
+
+        int count = 0;
+        while(count < 10) {
+            futures.add(executorService.submit(runnableTask));
+            count++;
+        }
+        futures.forEach(e -> {
+            try {
+                set.add(e.get());
+            } catch (Exception ex) {
+                throw new RuntimeException(ex);
+            }
+        });
+        executorService.shutdown();
+        assertEquals(1, set.size());
+    }
+
+}
@@ -0,0 +1,17 @@
+package com.baledung.billpugh;
+
+import static org.junit.jupiter.api.Assertions.*;
+import org.junit.jupiter.api.Test;
+
+public class LazyLoadedSingletonUnitTest {
+
+    @Test
+    void givenLazyLoadedImpl_whenCallGetInstance_thenReturnSingleInstance() throws ClassNotFoundException {
+        Class bs = Class.forName("com.baledung.billpugh.LazyLoadedSingleton");
+        assertThrows(IllegalAccessException.class, () -> bs.getDeclaredConstructor().newInstance());
+
+        LazyLoadedSingleton lazyLoadedSingletonObj1 = LazyLoadedSingleton.getInstance();
+        LazyLoadedSingleton lazyLoadedSingletonObj2 = LazyLoadedSingleton.getInstance();
+        assertEquals(lazyLoadedSingletonObj1.hashCode(), lazyLoadedSingletonObj2.hashCode());
+    }
+}
@@ -0,0 +1,44 @@
+package com.baledung.billpugh;
+
+import org.junit.jupiter.api.Test;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.util.ArrayList;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+import java.util.concurrent.*;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+public class SynchronizedLazyLoadedSingletonUnitTest {
+    Logger logger = LoggerFactory.getLogger(SynchronizedLazyLoadedSingletonUnitTest.class);
+    @Test
+    void giveSynchronizedLazyLoadedImpl_whenCallgetInstance_thenReturnSingleton() {
+        Set<SynchronizedLazyLoadedSingleton> setHoldingSingletonObj = new HashSet<>();
+        List<Future<SynchronizedLazyLoadedSingleton>> futures = new ArrayList<>();
+
+        ExecutorService executorService = Executors.newFixedThreadPool(10);
+        Callable<SynchronizedLazyLoadedSingleton> runnableTask = () -> {
+            logger.info("run called for:" + Thread.currentThread().getName());
+            return SynchronizedLazyLoadedSingleton.getInstance();
+        };
+
+        int count = 0;
+        while(count < 10) {
+            futures.add(executorService.submit(runnableTask));
+            count++;
+        }
+        futures.forEach(e -> {
+            try {
+                setHoldingSingletonObj.add(e.get());
+            } catch (Exception ex) {
+                throw new RuntimeException(ex);
+            }
+        });
+        executorService.shutdown();
+        assertEquals(1, setHoldingSingletonObj.size());
+    }
+
+}