Add isNotEmpty Utility Methods to Improve Readability and Safety

integration-tests/src/test/java/org/springframework/beans/factory/xml/ComponentBeanDefinitionParser.java

@@ -39,7 +39,7 @@ private static AbstractBeanDefinition parseComponentElement(Element element) {
 		factory.addPropertyValue("parent", parseComponent(element));
 
 		List<Element> childElements = DomUtils.getChildElementsByTagName(element, "component");
-		if (!CollectionUtils.isEmpty(childElements)) {
+		if (CollectionUtils.isNotEmpty(childElements)) {
 			parseChildComponents(childElements, factory);
 		}
 

integration-tests/src/test/java/org/springframework/beans/factory/xml/ComponentFactoryBean.java

@@ -19,6 +19,7 @@
 import java.util.List;
 
 import org.springframework.beans.factory.FactoryBean;
+import org.springframework.util.CollectionUtils;
 
 public class ComponentFactoryBean implements FactoryBean<Component> {
 
@@ -35,7 +36,7 @@ public void setChildren(List<Component> children) {
 
 	@Override
 	public Component getObject() {
-		if (this.children != null && this.children.size() > 0) {
+		if (this.children != null && CollectionUtils.isNotEmpty(this.children)) {
 			for (Component child : children) {
 				this.parent.addComponent(child);
 			}

spring-aop/src/main/java/org/springframework/aop/aspectj/AbstractAspectJAdvice.java

@@ -571,7 +571,7 @@ else if (this.joinPointStaticPartArgumentIndex != -1) {
 			numBound++;
 		}
 
-		if (!CollectionUtils.isEmpty(this.argumentBindings)) {
+		if (CollectionUtils.isNotEmpty(this.argumentBindings)) {
 			// binding from pointcut match
 			if (jpMatch != null) {
 				PointcutParameter[] parameterBindings = jpMatch.getParameterBindings();

spring-aop/src/main/java/org/springframework/aop/framework/AdvisedSupport.java

@@ -378,7 +378,7 @@ public void addAdvisors(Collection<Advisor> advisors) {
 		if (isFrozen()) {
 			throw new AopConfigException("Cannot add advisor: Configuration is frozen.");
 		}
-		if (!CollectionUtils.isEmpty(advisors)) {
+		if (CollectionUtils.isNotEmpty(advisors)) {
 			for (Advisor advisor : advisors) {
 				if (advisor instanceof IntroductionAdvisor introductionAdvisor) {
 					validateIntroductionAdvisor(introductionAdvisor);

spring-beans/src/main/java/org/springframework/beans/factory/annotation/InitDestroyAnnotationBeanPostProcessor.java

@@ -186,11 +186,11 @@ public void postProcessMergedBeanDefinition(RootBeanDefinition beanDefinition, C
 		RootBeanDefinition beanDefinition = registeredBean.getMergedBeanDefinition();
 		beanDefinition.resolveDestroyMethodIfNecessary();
 		LifecycleMetadata metadata = findLifecycleMetadata(beanDefinition, registeredBean.getBeanClass());
-		if (!CollectionUtils.isEmpty(metadata.initMethods)) {
+		if (CollectionUtils.isNotEmpty(metadata.initMethods)) {
 			String[] initMethodNames = safeMerge(beanDefinition.getInitMethodNames(), metadata.initMethods);
 			beanDefinition.setInitMethodNames(initMethodNames);
 		}
-		if (!CollectionUtils.isEmpty(metadata.destroyMethods)) {
+		if (CollectionUtils.isNotEmpty(metadata.destroyMethods)) {
 			String[] destroyMethodNames = safeMerge(beanDefinition.getDestroyMethodNames(), metadata.destroyMethods);
 			beanDefinition.setDestroyMethodNames(destroyMethodNames);
 		}

spring-beans/src/main/java/org/springframework/beans/factory/groovy/GroovyBeanDefinitionWrapper.java

@@ -103,7 +103,7 @@ AbstractBeanDefinition getBeanDefinition() {
 	protected AbstractBeanDefinition createBeanDefinition() {
 		AbstractBeanDefinition bd = new GenericBeanDefinition();
 		bd.setBeanClass(this.clazz);
-		if (!CollectionUtils.isEmpty(this.constructorArgs)) {
+		if (CollectionUtils.isNotEmpty(this.constructorArgs)) {
 			ConstructorArgumentValues cav = new ConstructorArgumentValues();
 			for (Object constructorArg : this.constructorArgs) {
 				cav.addGenericArgumentValue(constructorArg);

spring-beans/src/main/java/org/springframework/beans/factory/support/DisposableBeanAdapter.java

@@ -194,7 +194,7 @@ public void run() {
 
 	@Override
 	public void destroy() {
-		if (!CollectionUtils.isEmpty(this.beanPostProcessors)) {
+		if (CollectionUtils.isNotEmpty(this.beanPostProcessors)) {
 			for (DestructionAwareBeanPostProcessor processor : this.beanPostProcessors) {
 				processor.postProcessBeforeDestruction(this.bean, this.beanName);
 			}
@@ -448,7 +448,7 @@ public static boolean hasDestroyMethod(Object bean, RootBeanDefinition beanDefin
 	 * @param postProcessors the post-processor candidates
 	 */
 	public static boolean hasApplicableProcessors(Object bean, List<DestructionAwareBeanPostProcessor> postProcessors) {
-		if (!CollectionUtils.isEmpty(postProcessors)) {
+		if (CollectionUtils.isNotEmpty(postProcessors)) {
 			for (DestructionAwareBeanPostProcessor processor : postProcessors) {
 				if (processor.requiresDestruction(bean)) {
 					return true;
@@ -467,7 +467,7 @@ public static boolean hasApplicableProcessors(Object bean, List<DestructionAware
 			List<DestructionAwareBeanPostProcessor> processors, Object bean) {
 
 		List<DestructionAwareBeanPostProcessor> filteredPostProcessors = null;
-		if (!CollectionUtils.isEmpty(processors)) {
+		if (CollectionUtils.isNotEmpty(processors)) {
 			filteredPostProcessors = new ArrayList<>(processors.size());
 			for (DestructionAwareBeanPostProcessor processor : processors) {
 				if (processor.requiresDestruction(bean)) {

spring-context-support/src/main/java/org/springframework/ui/freemarker/FreeMarkerConfigurationFactory.java

@@ -299,7 +299,7 @@ public Configuration createConfiguration() throws IOException, TemplateException
 			config.setSettings(props);
 		}
 
-		if (!CollectionUtils.isEmpty(this.freemarkerVariables)) {
+		if (CollectionUtils.isNotEmpty(this.freemarkerVariables)) {
 			config.setAllSharedVariables(new SimpleHash(this.freemarkerVariables, config.getObjectWrapper()));
 		}
 

spring-context/src/main/java/org/springframework/cache/interceptor/AbstractFallbackCacheOperationSource.java

@@ -74,7 +74,7 @@ public abstract class AbstractFallbackCacheOperationSource implements CacheOpera
 
 	@Override
 	public boolean hasCacheOperations(Method method, @Nullable Class<?> targetClass) {
-		return !CollectionUtils.isEmpty(getCacheOperations(method, targetClass, false));
+		return CollectionUtils.isNotEmpty(getCacheOperations(method, targetClass, false));
 	}
 
 	@Override

spring-context/src/main/java/org/springframework/cache/interceptor/CacheAspectSupport.java

@@ -399,7 +399,7 @@ protected void clearMetadataCache() {
 			CacheOperationSource cacheOperationSource = getCacheOperationSource();
 			if (cacheOperationSource != null) {
 				Collection<CacheOperation> operations = cacheOperationSource.getCacheOperations(method, targetClass);
-				if (!CollectionUtils.isEmpty(operations)) {
+				if (CollectionUtils.isNotEmpty(operations)) {
 					return execute(invoker, method,
 							new CacheOperationContexts(operations, method, args, target, targetClass));
 				}

spring-context/src/main/java/org/springframework/cache/interceptor/CacheOperationSource.java

@@ -62,7 +62,7 @@ default boolean isCandidateClass(Class<?> targetClass) {
 	 * @see #getCacheOperations
 	 */
 	default boolean hasCacheOperations(Method method, @Nullable Class<?> targetClass) {
-		return !CollectionUtils.isEmpty(getCacheOperations(method, targetClass));
+		return CollectionUtils.isNotEmpty(getCacheOperations(method, targetClass));
 	}
 
 	/**

spring-context/src/main/java/org/springframework/context/annotation/ConfigurationClassPostProcessor.java

@@ -341,7 +341,7 @@ public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory)
 
 	@Override
 	public @Nullable BeanFactoryInitializationAotContribution processAheadOfTime(ConfigurableListableBeanFactory beanFactory) {
-		boolean hasPropertySourceDescriptors = !CollectionUtils.isEmpty(this.propertySourceDescriptors);
+		boolean hasPropertySourceDescriptors = CollectionUtils.isNotEmpty(this.propertySourceDescriptors);
 		boolean hasImportRegistry = beanFactory.containsBean(IMPORT_REGISTRY_BEAN_NAME);
 		boolean hasBeanRegistrars = !this.beanRegistrars.isEmpty();
 		if (hasPropertySourceDescriptors || hasImportRegistry || hasBeanRegistrars) {

spring-context/src/main/java/org/springframework/context/support/AbstractApplicationContext.java

@@ -914,7 +914,7 @@ protected void registerListeners() {
 		// Publish early application events now that we finally have a multicaster...
 		Set<ApplicationEvent> earlyEventsToProcess = this.earlyApplicationEvents;
 		this.earlyApplicationEvents = null;
-		if (!CollectionUtils.isEmpty(earlyEventsToProcess)) {
+		if (CollectionUtils.isNotEmpty(earlyEventsToProcess)) {
 			for (ApplicationEvent earlyEvent : earlyEventsToProcess) {
 				getApplicationEventMulticaster().multicastEvent(earlyEvent);
 			}

spring-context/src/main/java/org/springframework/context/support/DefaultLifecycleProcessor.java

@@ -591,7 +591,7 @@ public void start() {
 			for (LifecycleGroupMember member : this.members) {
 				doStart(this.lifecycleBeans, member.name, this.autoStartupOnly, futures);
 			}
-			if (concurrentStartup != null && !CollectionUtils.isEmpty(futures)) {
+			if (concurrentStartup != null && CollectionUtils.isNotEmpty(futures)) {
 				try {
 					CompletableFuture.allOf(futures.toArray(new CompletableFuture<?>[0]))
 							.get(concurrentStartup, TimeUnit.MILLISECONDS);

spring-context/src/main/java/org/springframework/context/support/ReloadableResourceBundleMessageSource.java

@@ -123,7 +123,7 @@ public class ReloadableResourceBundleMessageSource extends AbstractResourceBased
 	 * @since 6.1
 	 */
 	public void setFileExtensions(List<String> fileExtensions) {
-		Assert.isTrue(!CollectionUtils.isEmpty(fileExtensions), "At least one file extension is required");
+		Assert.isTrue(CollectionUtils.isNotEmpty(fileExtensions), "At least one file extension is required");
 		for (String extension : fileExtensions) {
 			if (!extension.startsWith(".")) {
 				throw new IllegalArgumentException("File extension '" + extension + "' should start with '.'");
@@ -379,18 +379,18 @@ protected List<String> calculateFilenamesForLocale(String basename, Locale local
 		StringBuilder temp = new StringBuilder(basename);
 
 		temp.append('_');
-		if (language.length() > 0) {
+		if (StringUtils.hasLength(language)) {
 			temp.append(language);
 			result.add(0, temp.toString());
 		}
 
 		temp.append('_');
-		if (country.length() > 0) {
+		if (StringUtils.hasLength(country)) {
 			temp.append(country);
 			result.add(0, temp.toString());
 		}
 
-		if (variant.length() > 0 && (language.length() > 0 || country.length() > 0)) {
+		if (StringUtils.hasLength(variant) && (StringUtils.hasLength(language) || StringUtils.hasLength(country))) {
 			temp.append('_').append(variant);
 			result.add(0, temp.toString());
 		}

spring-context/src/main/java/org/springframework/jmx/support/JmxUtils.java

@@ -95,7 +95,7 @@ public static MBeanServer locateMBeanServer(@Nullable String agentId) throws MBe
 		// null means any registered server, but "" specifically means the platform server
 		if (!"".equals(agentId)) {
 			List<MBeanServer> servers = MBeanServerFactory.findMBeanServer(agentId);
-			if (!CollectionUtils.isEmpty(servers)) {
+			if (CollectionUtils.isNotEmpty(servers)) {
 				// Check to see if an MBeanServer is registered.
 				if (servers.size() > 1 && logger.isInfoEnabled()) {
 					logger.info("Found more than one MBeanServer instance" +

spring-context/src/main/java/org/springframework/scheduling/config/ScheduledTaskRegistrar.java

@@ -395,11 +395,11 @@ public void addOneTimeTask(DelayedTask task) {
 	 * @since 3.2
 	 */
 	public boolean hasTasks() {
-		return (!CollectionUtils.isEmpty(this.triggerTasks) ||
-				!CollectionUtils.isEmpty(this.cronTasks) ||
-				!CollectionUtils.isEmpty(this.fixedRateTasks) ||
-				!CollectionUtils.isEmpty(this.fixedDelayTasks) ||
-				!CollectionUtils.isEmpty(this.oneTimeTasks));
+		return (CollectionUtils.isNotEmpty(this.triggerTasks) ||
+				CollectionUtils.isNotEmpty(this.cronTasks) ||
+				CollectionUtils.isNotEmpty(this.fixedRateTasks) ||
+				CollectionUtils.isNotEmpty(this.fixedDelayTasks) ||
+				CollectionUtils.isNotEmpty(this.oneTimeTasks));
 	}
 
 

spring-context/src/main/java/org/springframework/validation/beanvalidation/LocalValidatorFactoryBean.java

@@ -346,7 +346,7 @@ public List<String> getParameterNames(Method method) {
 	}
 
 	private void closeMappingStreams(@Nullable List<InputStream> mappingStreams){
-		if (!CollectionUtils.isEmpty(mappingStreams)) {
+		if (CollectionUtils.isNotEmpty(mappingStreams)) {
 			for (InputStream stream : mappingStreams) {
 				try {
 					stream.close();

spring-context/src/testFixtures/java/org/springframework/context/testfixture/jndi/SimpleNamingContext.java

@@ -326,7 +326,7 @@ private AbstractNamingEnumeration(SimpleNamingContext context, String proot) thr
 					}
 				}
 			}
-			if (contents.size() == 0) {
+			if (contents.isEmpty()) {
 				throw new NamingException("Invalid root: [" + context.root + proot + "]");
 			}
 			this.iterator = contents.values().iterator();

spring-core/src/main/java/org/springframework/asm/TypePath.java

@@ -117,7 +117,7 @@ public int getStepArgument(final int index) {
    * @return the corresponding TypePath object, or {@literal null} if the path is empty.
    */
   public static TypePath fromString(final String typePath) {
-    if (typePath == null || typePath.length() == 0) {
+    if (typePath == null || typePath.isEmpty()) {
       return null;
     }
     int typePathLength = typePath.length();

spring-core/src/main/java/org/springframework/cglib/proxy/CallbackHelper.java

@@ -63,7 +63,7 @@ public CallbackHelper(Class superclass, Class[] interfaces) {
     abstract protected Object getCallback(Method method);
 
     public Callback[] getCallbacks() {
-        if (callbacks.size() == 0) {
+        if (callbacks.isEmpty()) {
             return new Callback[0];
         }
         if (callbacks.get(0) instanceof Callback) {
@@ -75,7 +75,7 @@ public Callback[] getCallbacks() {
     }
 
     public Class[] getCallbackTypes() {
-        if (callbacks.size() == 0) {
+        if (callbacks.isEmpty()) {
             return new Class[0];
         }
         if (callbacks.get(0) instanceof Callback) {

spring-core/src/main/java/org/springframework/cglib/proxy/Enhancer.java

@@ -755,7 +755,7 @@ public void generateClass(ClassVisitor v) throws Exception {
 	 */
 	protected void filterConstructors(Class sc, List constructors) {
 		CollectionUtils.filter(constructors, new VisibilityPredicate(sc, true));
-		if (constructors.size() == 0) {
+		if (constructors.isEmpty()) {
 			throw new IllegalArgumentException("No visible constructors in " + sc);
 		}
 	}

spring-core/src/main/java/org/springframework/core/io/support/LocalizedResourceHelper.java

@@ -24,6 +24,7 @@
 import org.springframework.core.io.Resource;
 import org.springframework.core.io.ResourceLoader;
 import org.springframework.util.Assert;
+import org.springframework.util.StringUtils;
 
 /**
  * Helper class for loading a localized resource,
@@ -100,20 +101,20 @@ public Resource findLocalizedResource(String name, String extension, @Nullable L
 			String variant = locale.getVariant();
 
 			// Check for file with language, country and variant localization.
-			if (variant.length() > 0) {
+			if (StringUtils.hasLength(variant)) {
 				String location =
 						name + this.separator + lang + this.separator + country + this.separator + variant + extension;
 				resource = this.resourceLoader.getResource(location);
 			}
 
 			// Check for file with language and country localization.
-			if ((resource == null || !resource.exists()) && country.length() > 0) {
+			if ((resource == null || !resource.exists()) && StringUtils.hasLength(country)) {
 				String location = name + this.separator + lang + this.separator + country + extension;
 				resource = this.resourceLoader.getResource(location);
 			}
 
 			// Check for document with language localization.
-			if ((resource == null || !resource.exists()) && lang.length() > 0) {
+			if ((resource == null || !resource.exists()) && StringUtils.hasLength(lang)) {
 				String location = name + this.separator + lang + extension;
 				resource = this.resourceLoader.getResource(location);
 			}

spring-core/src/main/java/org/springframework/core/io/support/PropertySourceProcessor.java

@@ -35,6 +35,7 @@
 import org.springframework.core.io.Resource;
 import org.springframework.core.io.ResourceLoader;
 import org.springframework.util.Assert;
+import org.springframework.util.CollectionUtils;
 import org.springframework.util.PlaceholderResolutionException;
 import org.springframework.util.ReflectionUtils;
 
@@ -80,7 +81,7 @@ public void processPropertySource(PropertySourceDescriptor descriptor) throws IO
 		String name = descriptor.name();
 		String encoding = descriptor.encoding();
 		List<String> locations = descriptor.locations();
-		Assert.isTrue(locations.size() > 0, "At least one @PropertySource(value) location is required");
+		Assert.isTrue(CollectionUtils.isNotEmpty(locations), "At least one @PropertySource(value) location is required");
 		boolean ignoreResourceNotFound = descriptor.ignoreResourceNotFound();
 		PropertySourceFactory factory = (descriptor.propertySourceFactory() != null ?
 				instantiateClass(descriptor.propertySourceFactory()) : defaultPropertySourceFactory);

spring-core/src/main/java/org/springframework/util/AntPathMatcher.java

@@ -348,7 +348,7 @@ private boolean isPotentialMatch(String path, String[] pattDirs) {
 				pos += skipped;
 				skipped = skipSegment(path, pos, pattDir);
 				if (skipped < pattDir.length()) {
-					return (skipped > 0 || (pattDir.length() > 0 && isWildcardChar(pattDir.charAt(0))));
+					return (skipped > 0 || (StringUtils.hasLength(pattDir) && isWildcardChar(pattDir.charAt(0))));
 				}
 				pos += skipped;
 			}

spring-core/src/main/java/org/springframework/util/ClassUtils.java

@@ -753,7 +753,7 @@ public static String classNamesToString(@Nullable Collection<Class<?>> classes)
 	 * @see StringUtils#toStringArray
 	 */
 	public static Class<?>[] toClassArray(@Nullable Collection<Class<?>> collection) {
-		return (!CollectionUtils.isEmpty(collection) ? collection.toArray(EMPTY_CLASS_ARRAY) : EMPTY_CLASS_ARRAY);
+		return (CollectionUtils.isNotEmpty(collection) ? collection.toArray(EMPTY_CLASS_ARRAY) : EMPTY_CLASS_ARRAY);
 	}
 
 	/**

spring-core/src/main/java/org/springframework/util/CollectionUtils.java

@@ -80,6 +80,27 @@ public static boolean isEmpty(@Nullable Map<?, ? extends @Nullable Object> map)
 		return (map == null || map.isEmpty());
 	}
 
+	/**
+	 * Return {@code true} if the supplied Collection is not {@code null} and not empty.
+	 * Otherwise, return {@code false}.
+	 * @param collection the Collection to check
+	 * @return whether the given Collection is not empty
+	 */
+	public static boolean isNotEmpty(@Nullable Collection<? extends @Nullable Object> collection) {
+		return (collection != null && !collection.isEmpty());
+	}
+
+	/**
+	 * Return {@code true} if the supplied Map is not {@code null} and not empty.
+	 * Otherwise, return {@code false}.
+	 * @param map the Map to check
+	 * @return whether the given Map is not empty
+	 */
+	public static boolean isNotEmpty(@Nullable Map<?, ? extends @Nullable Object> map) {
+		return (map != null && !map.isEmpty());
+	}
+
+
 	/**
 	 * Instantiate a new {@link HashMap} with an initial capacity
 	 * that can accommodate the specified number of elements without

spring-core/src/main/java/org/springframework/util/CommonsLogWriter.java

@@ -44,7 +44,7 @@ public CommonsLogWriter(Log logger) {
 
 
 	public void write(char ch) {
-		if (ch == '\n' && this.buffer.length() > 0) {
+		if (ch == '\n' && StringUtils.hasLength(this.buffer)) {
 			logger.debug(this.buffer.toString());
 			this.buffer.setLength(0);
 		}

spring-core/src/main/java/org/springframework/util/MimeType.java

@@ -181,7 +181,7 @@ public MimeType(String type, String subtype, @Nullable Map<String, String> param
 		checkToken(subtype);
 		this.type = type.toLowerCase(Locale.ROOT);
 		this.subtype = subtype.toLowerCase(Locale.ROOT);
-		if (!CollectionUtils.isEmpty(parameters)) {
+		if (CollectionUtils.isNotEmpty(parameters)) {
 			Map<String, String> map = new LinkedCaseInsensitiveMap<>(parameters.size(), Locale.ROOT);
 			parameters.forEach((parameter, value) -> {
 				checkParameters(parameter, value);

spring-core/src/main/java/org/springframework/util/MimeTypeUtils.java

@@ -244,7 +244,7 @@ else if (ch == '"') {
 				nextIndex++;
 			}
 			String parameter = mimeType.substring(index + 1, nextIndex).trim();
-			if (parameter.length() > 0) {
+			if (StringUtils.hasLength(parameter)) {
 				if (parameters == null) {
 					parameters = new LinkedHashMap<>(4);
 				}

spring-core/src/main/java/org/springframework/util/MultiToSingleValueMapAdapter.java

@@ -201,7 +201,7 @@ public void forEach(BiConsumer<? super K, ? super V> action) {
 	}
 
 	private @Nullable V adaptValue(@Nullable List<V> values) {
-		if (!CollectionUtils.isEmpty(values)) {
+		if (CollectionUtils.isNotEmpty(values)) {
 			return values.get(0);
 		}
 		else {