Collection.isEmpty() should be used to test for emptiness

Closes gh-1670

spring-context/src/main/java/org/springframework/cache/config/CacheAdviceParser.java

@@ -72,7 +72,7 @@ class CacheAdviceParser extends AbstractSingleBeanDefinitionParser {
 		CacheNamespaceHandler.parseKeyGenerator(element, builder.getBeanDefinition());
 
 		List<Element> cacheDefs = DomUtils.getChildElementsByTagName(element, DEFS_ELEMENT);
-		if (cacheDefs.size() >= 1) {
+		if (!cacheDefs.isEmpty()) {
 			// Using attributes source.
 			List<RootBeanDefinition> attributeSourceDefinitions = parseDefinitionsSources(cacheDefs, parserContext);
 			builder.addPropertyValue("cacheOperationSources", attributeSourceDefinitions);

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

@@ -95,7 +95,7 @@ public abstract class JmxUtils {
 		// null means any registered server, but "" specifically means the platform server
 		if (!"".equals(agentId)) {
 			List<MBeanServer> servers = MBeanServerFactory.findMBeanServer(agentId);
-			if (servers != null && servers.size() > 0) {
+			if (servers != null && !servers.isEmpty()) {
 				// Check to see if an MBeanServer is registered.
 				if (servers.size() > 1 && logger.isWarnEnabled()) {
 					logger.warn("Found more than one MBeanServer instance" +

spring-context/src/main/java/org/springframework/validation/DataBinder.java

@@ -568,7 +568,7 @@ public class DataBinder implements PropertyEditorRegistry, TypeConverter {
 	 */
 	@Nullable
 	public Validator getValidator() {
-		return (this.validators.size() > 0 ? this.validators.get(0) : null);
+		return (!this.validators.isEmpty() ? this.validators.get(0) : null);
 	}
 
 	/**

spring-core/src/main/java/org/springframework/core/codec/StringDecoder.java

@@ -188,7 +188,7 @@ public class StringDecoder extends AbstractDataBufferDecoder<String> {
 	 * Joins the given list of buffers into a single buffer.
 	 */
 	private static Mono<DataBuffer> joinUntilEndFrame(List<DataBuffer> dataBuffers) {
-		if (dataBuffers.size() > 0) {
+		if (!dataBuffers.isEmpty()) {
 			int lastIdx = dataBuffers.size() - 1;
 			if (isEndFrame(dataBuffers.get(lastIdx))) {
 				dataBuffers.remove(lastIdx);

spring-jdbc/src/main/java/org/springframework/jdbc/config/DatabasePopulatorConfigUtils.java

@@ -40,7 +40,7 @@ class DatabasePopulatorConfigUtils {
 
 	public static void setDatabasePopulator(Element element, BeanDefinitionBuilder builder) {
 		List<Element> scripts = DomUtils.getChildElementsByTagName(element, "script");
-		if (scripts.size() > 0) {
+		if (!scripts.isEmpty()) {
 			builder.addPropertyValue("databasePopulator", createDatabasePopulator(element, scripts, "INIT"));
 			builder.addPropertyValue("databaseCleaner", createDatabasePopulator(element, scripts, "DESTROY"));
 		}

spring-jdbc/src/main/java/org/springframework/jdbc/core/metadata/CallMetaDataContext.java

@@ -293,7 +293,7 @@ public class CallMetaDataContext {
 			if (this.outParameterNames.size() > 1) {
 				logger.warn("Accessing single output value when procedure has more than one output parameter");
 			}
-			return (this.outParameterNames.size() > 0 ? this.outParameterNames.get(0) : null);
+			return (!this.outParameterNames.isEmpty() ? this.outParameterNames.get(0) : null);
 		}
 	}
 
@@ -388,7 +388,7 @@ public class CallMetaDataContext {
 				SqlParameter param;
 				if (meta.getParameterType() == DatabaseMetaData.procedureColumnReturn) {
 					param = declaredParams.get(getFunctionReturnName());
-					if (param == null && getOutParameterNames().size() > 0) {
+					if (param == null && !getOutParameterNames().isEmpty()) {
 						param = declaredParams.get(getOutParameterNames().get(0).toLowerCase());
 					}
 					if (param == null) {

spring-jdbc/src/main/java/org/springframework/jdbc/core/metadata/TableMetaDataContext.java

@@ -184,7 +184,7 @@ public class TableMetaDataContext {
 		if (generatedKeyNames.length > 0) {
 			this.generatedKeyColumnsUsed = true;
 		}
-		if (declaredColumns.size() > 0) {
+		if (!declaredColumns.isEmpty()) {
 			return new ArrayList<>(declaredColumns);
 		}
 		Set<String> keys = new LinkedHashSet<>(generatedKeyNames.length);

spring-jdbc/src/main/java/org/springframework/jdbc/support/GeneratedKeyHolder.java

@@ -61,7 +61,7 @@ public class GeneratedKeyHolder implements KeyHolder {
 	@Override
 	@Nullable
 	public Number getKey() throws InvalidDataAccessApiUsageException, DataRetrievalFailureException {
-		if (this.keyList.size() == 0) {
+		if (this.keyList.isEmpty()) {
 			return null;
 		}
 		if (this.keyList.size() > 1 || this.keyList.get(0).size() > 1) {
@@ -89,7 +89,7 @@ public class GeneratedKeyHolder implements KeyHolder {
 	@Override
 	@Nullable
 	public Map<String, Object> getKeys() throws InvalidDataAccessApiUsageException {
-		if (this.keyList.size() == 0) {
+		if (this.keyList.isEmpty()) {
 			return null;
 		}
 		if (this.keyList.size() > 1)

spring-test/src/main/java/org/springframework/test/context/BootstrapUtils.java

@@ -151,7 +151,7 @@ abstract class BootstrapUtils {
 	@Nullable
 	private static Class<?> resolveExplicitTestContextBootstrapper(Class<?> testClass) {
 		Set<BootstrapWith> annotations = AnnotatedElementUtils.findAllMergedAnnotations(testClass, BootstrapWith.class);
-		if (annotations.size() < 1) {
+		if (annotations.isEmpty()) {
 			return null;
 		}
 		Assert.state(annotations.size() <= 1, () -> String.format(

spring-test/src/main/java/org/springframework/test/web/ModelAndViewAssert.java

@@ -201,7 +201,7 @@ public abstract class ModelAndViewAssert {
 		tempSet.addAll(incorrectSet);
 		tempSet.removeAll(assertionSet);
 
-		if (tempSet.size() > 0) {
+		if (!tempSet.isEmpty()) {
 			sb.append("Set has too many elements:\n");
 			for (Object element : tempSet) {
 				sb.append('-');
@@ -214,7 +214,7 @@ public abstract class ModelAndViewAssert {
 		tempSet.addAll(assertionSet);
 		tempSet.removeAll(incorrectSet);
 
-		if (tempSet.size() > 0) {
+		if (!tempSet.isEmpty()) {
 			sb.append("Set is missing elements:\n");
 			for (Object element : tempSet) {
 				sb.append('-');

spring-web/src/main/java/org/springframework/web/util/pattern/RegexPathElement.java

@@ -136,7 +136,7 @@ class RegexPathElement extends PathElement {
 		if (matches) {
 			if (isNoMorePattern()) {
 				if (matchingContext.determineRemainingPath && 
-					((this.variableNames.size() == 0) ? true : textToMatch.length() > 0)) {
+					(this.variableNames.isEmpty() ? true : textToMatch.length() > 0)) {
 					matchingContext.remainingPathIndex = pathIndex + 1;
 					matches = true;
 				}

spring-webflux/src/main/java/org/springframework/web/reactive/result/method/annotation/InitBinderBindingContext.java

@@ -79,7 +79,7 @@ class InitBinderBindingContext extends BindingContext {
 					InitBinder ann = binderMethod.getMethodAnnotation(InitBinder.class);
 					Assert.state(ann != null, "No InitBinder annotation");
 					Collection<String> names = Arrays.asList(ann.value());
-					return (names.size() == 0 || names.contains(dataBinder.getObjectName()));
+					return (names.isEmpty() || names.contains(dataBinder.getObjectName()));
 				})
 				.forEach(method -> invokeBinderMethod(dataBinder, exchange, method));
 

spring-webmvc/src/main/java/org/springframework/web/servlet/tags/form/TagWriter.java

@@ -191,7 +191,7 @@ public class TagWriter {
 	}
 
 	private boolean inTag() {
-		return this.tagState.size() > 0;
+		return !this.tagState.isEmpty();
 	}
 
 	private TagStateEntry currentState() {

spring-webmvc/src/main/java/org/springframework/web/servlet/view/groovy/GroovyMarkupConfigurer.java

@@ -180,7 +180,7 @@ public class GroovyMarkupConfigurer extends TemplateConfiguration
 		}
 		ClassLoader classLoader = getApplicationContext().getClassLoader();
 		Assert.state(classLoader != null, "No ClassLoader");
-		return (urls.size() > 0 ? new URLClassLoader(urls.toArray(new URL[urls.size()]), classLoader) : classLoader);
+		return (!urls.isEmpty() ? new URLClassLoader(urls.toArray(new URL[urls.size()]), classLoader) : classLoader);
 	}
 
 	/**