Prefer ArrayList/ArrayDeque over LinkedList for multi-element holders

LinkedList remains in place where a List is likely to remain empty or single-element (in order to avoid unused capacity).

Issue: SPR-17037

Author: jhoeller

spring-aop/src/main/java/org/springframework/aop/aspectj/annotation/BeanFactoryAspectJAdvisorsBuilder.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2017 the original author or authors.
+ * Copyright 2002-2018 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,8 +16,8 @@
 
 package org.springframework.aop.aspectj.annotation;
 
+import java.util.ArrayList;
 import java.util.Collections;
-import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
 import java.util.concurrent.ConcurrentHashMap;
@@ -87,8 +87,8 @@ public List<Advisor> buildAspectJAdvisors() {
 			synchronized (this) {
 				aspectNames = this.aspectBeanNames;
 				if (aspectNames == null) {
-					List<Advisor> advisors = new LinkedList<>();
-					aspectNames = new LinkedList<>();
+					List<Advisor> advisors = new ArrayList<>();
+					aspectNames = new ArrayList<>();
 					String[] beanNames = BeanFactoryUtils.beanNamesForTypeIncludingAncestors(
 							this.beanFactory, Object.class, true, false);
 					for (String beanName : beanNames) {
@@ -138,7 +138,7 @@ public List<Advisor> buildAspectJAdvisors() {
 		if (aspectNames.isEmpty()) {
 			return Collections.emptyList();
 		}
-		List<Advisor> advisors = new LinkedList<>();
+		List<Advisor> advisors = new ArrayList<>();
 		for (String aspectName : aspectNames) {
 			List<Advisor> cachedAdvisors = this.advisorsCache.get(aspectName);
 			if (cachedAdvisors != null) {

spring-aop/src/main/java/org/springframework/aop/aspectj/annotation/ReflectiveAspectJAdvisorFactory.java

@@ -20,8 +20,8 @@
 import java.lang.annotation.Annotation;
 import java.lang.reflect.Field;
 import java.lang.reflect.Method;
+import java.util.ArrayList;
 import java.util.Comparator;
-import java.util.LinkedList;
 import java.util.List;
 
 import org.aopalliance.aop.Advice;
@@ -121,7 +121,7 @@ public List<Advisor> getAdvisors(MetadataAwareAspectInstanceFactory aspectInstan
 		MetadataAwareAspectInstanceFactory lazySingletonAspectInstanceFactory =
 				new LazySingletonAspectInstanceFactoryDecorator(aspectInstanceFactory);
 
-		List<Advisor> advisors = new LinkedList<>();
+		List<Advisor> advisors = new ArrayList<>();
 		for (Method method : getAdvisorMethods(aspectClass)) {
 			Advisor advisor = getAdvisor(method, lazySingletonAspectInstanceFactory, advisors.size(), aspectName);
 			if (advisor != null) {
@@ -147,7 +147,7 @@ public List<Advisor> getAdvisors(MetadataAwareAspectInstanceFactory aspectInstan
 	}
 
 	private List<Method> getAdvisorMethods(Class<?> aspectClass) {
-		final List<Method> methods = new LinkedList<>();
+		final List<Method> methods = new ArrayList<>();
 		ReflectionUtils.doWithMethods(aspectClass, method -> {
 			// Exclude pointcuts
 			if (AnnotationUtils.getAnnotation(method, Pointcut.class) == null) {

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

@@ -34,7 +34,7 @@ public class ProxyCreatorSupport extends AdvisedSupport {
 
 	private AopProxyFactory aopProxyFactory;
 
-	private List<AdvisedSupportListener> listeners = new LinkedList<>();
+	private final List<AdvisedSupportListener> listeners = new LinkedList<>();
 
 	/** Set to true when the first AOP proxy has been created. */
 	private boolean active = false;

spring-aop/src/main/java/org/springframework/aop/framework/autoproxy/BeanFactoryAdvisorRetrievalHelper.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2017 the original author or authors.
+ * Copyright 2002-2018 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,7 +16,7 @@
 
 package org.springframework.aop.framework.autoproxy;
 
-import java.util.LinkedList;
+import java.util.ArrayList;
 import java.util.List;
 
 import org.apache.commons.logging.Log;
@@ -78,10 +78,10 @@ public List<Advisor> findAdvisorBeans() {
 			}
 		}
 		if (advisorNames.length == 0) {
-			return new LinkedList<>();
+			return new ArrayList<>();
 		}
 
-		List<Advisor> advisors = new LinkedList<>();
+		List<Advisor> advisors = new ArrayList<>();
 		for (String name : advisorNames) {
 			if (isEligibleBean(name)) {
 				if (this.beanFactory.isCurrentlyInCreation(name)) {

spring-aop/src/main/java/org/springframework/aop/support/AopUtils.java

@@ -20,8 +20,8 @@
 import java.lang.reflect.Method;
 import java.lang.reflect.Modifier;
 import java.lang.reflect.Proxy;
+import java.util.ArrayList;
 import java.util.LinkedHashSet;
-import java.util.LinkedList;
 import java.util.List;
 import java.util.Set;
 
@@ -305,7 +305,7 @@ public static List<Advisor> findAdvisorsThatCanApply(List<Advisor> candidateAdvi
 		if (candidateAdvisors.isEmpty()) {
 			return candidateAdvisors;
 		}
-		List<Advisor> eligibleAdvisors = new LinkedList<>();
+		List<Advisor> eligibleAdvisors = new ArrayList<>();
 		for (Advisor candidate : candidateAdvisors) {
 			if (candidate instanceof IntroductionAdvisor && canApply(candidate, clazz)) {
 				eligibleAdvisors.add(candidate);

spring-aop/src/main/java/org/springframework/aop/support/NameMatchMethodPointcut.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2017 the original author or authors.
+ * Copyright 2002-2018 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -18,8 +18,8 @@
 
 import java.io.Serializable;
 import java.lang.reflect.Method;
+import java.util.ArrayList;
 import java.util.Arrays;
-import java.util.LinkedList;
 import java.util.List;
 
 import org.springframework.lang.Nullable;
@@ -38,7 +38,7 @@
 @SuppressWarnings("serial")
 public class NameMatchMethodPointcut extends StaticMethodMatcherPointcut implements Serializable {
 
-	private List<String> mappedNames = new LinkedList<>();
+	private List<String> mappedNames = new ArrayList<>();
 
 
 	/**
@@ -55,11 +55,8 @@ public void setMappedName(String mappedName) {
 	 * Matching will be the union of all these; if any match,
 	 * the pointcut matches.
 	 */
-	public void setMappedNames(@Nullable String... mappedNames) {
-		this.mappedNames = new LinkedList<>();
-		if (mappedNames != null) {
-			this.mappedNames.addAll(Arrays.asList(mappedNames));
-		}
+	public void setMappedNames(String... mappedNames) {
+		this.mappedNames = new ArrayList<>(Arrays.asList(mappedNames));
 	}
 
 	/**

spring-aop/src/test/java/org/springframework/aop/support/NameMatchMethodPointcutTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2013 the original author or authors.
+ * Copyright 2002-2018 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -41,18 +41,20 @@ public class NameMatchMethodPointcutTests {
 
 	protected SerializableNopInterceptor nop;
 
+
 	/**
 	 * Create an empty pointcut, populating instance variables.
 	 */
 	@Before
-	public void setUp() {
+	public void setup() {
 		ProxyFactory pf = new ProxyFactory(new SerializablePerson());
 		nop = new SerializableNopInterceptor();
 		pc = new NameMatchMethodPointcut();
 		pf.addAdvisor(new DefaultPointcutAdvisor(pc, nop));
 		proxied = (Person) pf.getProxy();
 	}
 
+
 	@Test
 	public void testMatchingOnly() {
 		// Can't do exact matching through isMatch
@@ -94,7 +96,7 @@ public void testMatchOneMethod() throws Throwable {
 
 	@Test
 	public void testSets() throws Throwable {
-		pc.setMappedNames(new String[] { "set*", "echo" });
+		pc.setMappedNames("set*", "echo");
 		assertEquals(0, nop.getCount());
 		proxied.getName();
 		proxied.setName("");
@@ -116,7 +118,7 @@ public void testSerializable() throws Throwable {
 	}
 
 	@Test
-	public void testEqualsAndHashCode() throws Exception {
+	public void testEqualsAndHashCode() {
 		NameMatchMethodPointcut pc1 = new NameMatchMethodPointcut();
 		NameMatchMethodPointcut pc2 = new NameMatchMethodPointcut();
 

spring-beans/src/main/java/org/springframework/beans/AbstractPropertyAccessor.java

@@ -16,8 +16,8 @@
 
 package org.springframework.beans;
 
+import java.util.ArrayList;
 import java.util.Arrays;
-import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
 
@@ -110,7 +110,7 @@ public void setPropertyValues(PropertyValues pvs, boolean ignoreUnknown, boolean
 			}
 			catch (PropertyAccessException ex) {
 				if (propertyAccessExceptions == null) {
-					propertyAccessExceptions = new LinkedList<>();
+					propertyAccessExceptions = new ArrayList<>();
 				}
 				propertyAccessExceptions.add(ex);
 			}

spring-beans/src/main/java/org/springframework/beans/PropertyEditorRegistrySupport.java

@@ -27,12 +27,12 @@
 import java.nio.charset.Charset;
 import java.nio.file.Path;
 import java.time.ZoneId;
+import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Currency;
 import java.util.HashMap;
 import java.util.Iterator;
 import java.util.LinkedHashMap;
-import java.util.LinkedList;
 import java.util.List;
 import java.util.Locale;
 import java.util.Map;
@@ -318,7 +318,7 @@ public PropertyEditor findCustomEditor(@Nullable Class<?> requiredType, @Nullabl
 				// Check property-specific editor first.
 				PropertyEditor editor = getCustomEditor(propertyPath, requiredType);
 				if (editor == null) {
-					List<String> strippedPaths = new LinkedList<>();
+					List<String> strippedPaths = new ArrayList<>();
 					addStrippedPropertyPaths(strippedPaths, "", propertyPath);
 					for (Iterator<String> it = strippedPaths.iterator(); it.hasNext() && editor == null;) {
 						String strippedPath = it.next();
@@ -438,7 +438,7 @@ protected Class<?> guessPropertyTypeFromEditors(String propertyName) {
 		if (this.customEditorsForPath != null) {
 			CustomEditorHolder editorHolder = this.customEditorsForPath.get(propertyName);
 			if (editorHolder == null) {
-				List<String> strippedPaths = new LinkedList<>();
+				List<String> strippedPaths = new ArrayList<>();
 				addStrippedPropertyPaths(strippedPaths, "", propertyName);
 				for (Iterator<String> it = strippedPaths.iterator(); it.hasNext() && editorHolder == null;) {
 					String strippedName = it.next();

spring-beans/src/main/java/org/springframework/beans/factory/BeanCreationException.java

@@ -18,7 +18,7 @@
 
 import java.io.PrintStream;
 import java.io.PrintWriter;
-import java.util.LinkedList;
+import java.util.ArrayList;
 import java.util.List;
 
 import org.springframework.beans.FatalBeanException;
@@ -141,7 +141,7 @@ public String getBeanName() {
 	 */
 	public void addRelatedCause(Throwable ex) {
 		if (this.relatedCauses == null) {
-			this.relatedCauses = new LinkedList<>();
+			this.relatedCauses = new ArrayList<>();
 		}
 		this.relatedCauses.add(ex);
 	}

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

@@ -28,7 +28,6 @@
 import java.util.Collections;
 import java.util.Iterator;
 import java.util.LinkedHashSet;
-import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
@@ -430,11 +429,11 @@ private InjectionMetadata findAutowiringMetadata(String beanName, Class<?> clazz
 	}
 
 	private InjectionMetadata buildAutowiringMetadata(final Class<?> clazz) {
-		LinkedList<InjectionMetadata.InjectedElement> elements = new LinkedList<>();
+		List<InjectionMetadata.InjectedElement> elements = new ArrayList<>();
 		Class<?> targetClass = clazz;
 
 		do {
-			final LinkedList<InjectionMetadata.InjectedElement> currElements = new LinkedList<>();
+			final List<InjectionMetadata.InjectedElement> currElements = new ArrayList<>();
 
 			ReflectionUtils.doWithLocalFields(targetClass, field -> {
 				AnnotationAttributes ann = findAutowiredAnnotation(field);

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

@@ -23,9 +23,10 @@
 import java.lang.reflect.InvocationTargetException;
 import java.lang.reflect.Method;
 import java.lang.reflect.Modifier;
+import java.util.ArrayList;
 import java.util.Collection;
 import java.util.LinkedHashSet;
-import java.util.LinkedList;
+import java.util.List;
 import java.util.Map;
 import java.util.Set;
 import java.util.concurrent.ConcurrentHashMap;
@@ -196,13 +197,13 @@ private LifecycleMetadata findLifecycleMetadata(Class<?> clazz) {
 
 	private LifecycleMetadata buildLifecycleMetadata(final Class<?> clazz) {
 		final boolean debug = logger.isDebugEnabled();
-		LinkedList<LifecycleElement> initMethods = new LinkedList<>();
-		LinkedList<LifecycleElement> destroyMethods = new LinkedList<>();
+		List<LifecycleElement> initMethods = new ArrayList<>();
+		List<LifecycleElement> destroyMethods = new ArrayList<>();
 		Class<?> targetClass = clazz;
 
 		do {
-			final LinkedList<LifecycleElement> currInitMethods = new LinkedList<>();
-			final LinkedList<LifecycleElement> currDestroyMethods = new LinkedList<>();
+			final List<LifecycleElement> currInitMethods = new ArrayList<>();
+			final List<LifecycleElement> currDestroyMethods = new ArrayList<>();
 
 			ReflectionUtils.doWithLocalMethods(targetClass, method -> {
 				if (this.initAnnotationType != null && method.isAnnotationPresent(this.initAnnotationType)) {

spring-beans/src/main/java/org/springframework/beans/factory/config/ConstructorArgumentValues.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2017 the original author or authors.
+ * Copyright 2002-2018 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,10 +16,10 @@
 
 package org.springframework.beans.factory.config;
 
+import java.util.ArrayList;
 import java.util.Collections;
 import java.util.Iterator;
 import java.util.LinkedHashMap;
-import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
@@ -45,7 +45,7 @@ public class ConstructorArgumentValues {
 
 	private final Map<Integer, ValueHolder> indexedArgumentValues = new LinkedHashMap<>(0);
 
-	private final List<ValueHolder> genericArgumentValues = new LinkedList<>();
+	private final List<ValueHolder> genericArgumentValues = new ArrayList<>();
 
 
 	/**

spring-beans/src/main/java/org/springframework/beans/factory/parsing/CompositeComponentDefinition.java

@@ -16,7 +16,7 @@
 
 package org.springframework.beans.factory.parsing;
 
-import java.util.LinkedList;
+import java.util.ArrayList;
 import java.util.List;
 
 import org.springframework.lang.Nullable;
@@ -38,7 +38,7 @@ public class CompositeComponentDefinition extends AbstractComponentDefinition {
 	@Nullable
 	private final Object source;
 
-	private final List<ComponentDefinition> nestedComponents = new LinkedList<>();
+	private final List<ComponentDefinition> nestedComponents = new ArrayList<>();
 
 
 	/**

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

@@ -30,7 +30,6 @@
 import java.util.Collection;
 import java.util.HashSet;
 import java.util.LinkedHashSet;
-import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
@@ -1518,7 +1517,7 @@ protected PropertyDescriptor[] filterPropertyDescriptorsForDependencyCheck(BeanW
 	 * @see #isExcludedFromDependencyCheck
 	 */
 	protected PropertyDescriptor[] filterPropertyDescriptorsForDependencyCheck(BeanWrapper bw) {
-		List<PropertyDescriptor> pds = new LinkedList<>(Arrays.asList(bw.getPropertyDescriptors()));
+		List<PropertyDescriptor> pds = new ArrayList<>(Arrays.asList(bw.getPropertyDescriptors()));
 		pds.removeIf(this::isExcludedFromDependencyCheck);
 		return pds.toArray(new PropertyDescriptor[0]);
 	}