Replace if with switch where feasible

See gh-31916

spring-aop/src/main/java/org/springframework/aop/config/ConfigBeanDefinitionParser.java

@@ -404,24 +404,14 @@ class ConfigBeanDefinitionParser implements BeanDefinitionParser {
 	 */
 	private Class<?> getAdviceClass(Element adviceElement, ParserContext parserContext) {
 		String elementName = parserContext.getDelegate().getLocalName(adviceElement);
-		if (BEFORE.equals(elementName)) {
-			return AspectJMethodBeforeAdvice.class;
-		}
-		else if (AFTER.equals(elementName)) {
-			return AspectJAfterAdvice.class;
-		}
-		else if (AFTER_RETURNING_ELEMENT.equals(elementName)) {
-			return AspectJAfterReturningAdvice.class;
-		}
-		else if (AFTER_THROWING_ELEMENT.equals(elementName)) {
-			return AspectJAfterThrowingAdvice.class;
-		}
-		else if (AROUND.equals(elementName)) {
-			return AspectJAroundAdvice.class;
-		}
-		else {
-			throw new IllegalArgumentException("Unknown advice kind [" + elementName + "].");
-		}
+		return switch (elementName) {
+			case BEFORE -> AspectJMethodBeforeAdvice.class;
+			case AFTER -> AspectJAfterAdvice.class;
+			case AFTER_RETURNING_ELEMENT -> AspectJAfterReturningAdvice.class;
+			case AFTER_THROWING_ELEMENT -> AspectJAfterThrowingAdvice.class;
+			case AROUND -> AspectJAroundAdvice.class;
+			default -> throw new IllegalArgumentException("Unknown advice kind [" + elementName + "].");
+		};
 	}
 
 	/**

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

@@ -182,17 +182,12 @@ public class ComponentScanBeanDefinitionParser implements BeanDefinitionParser {
 
 		if (element.hasAttribute(SCOPED_PROXY_ATTRIBUTE)) {
 			String mode = element.getAttribute(SCOPED_PROXY_ATTRIBUTE);
-			if ("targetClass".equals(mode)) {
-				scanner.setScopedProxyMode(ScopedProxyMode.TARGET_CLASS);
-			}
-			else if ("interfaces".equals(mode)) {
-				scanner.setScopedProxyMode(ScopedProxyMode.INTERFACES);
-			}
-			else if ("no".equals(mode)) {
-				scanner.setScopedProxyMode(ScopedProxyMode.NO);
-			}
-			else {
-				throw new IllegalArgumentException("scoped-proxy only supports 'no', 'interfaces' and 'targetClass'");
+			switch (mode) {
+				case "targetClass" -> scanner.setScopedProxyMode(ScopedProxyMode.TARGET_CLASS);
+				case "interfaces" -> scanner.setScopedProxyMode(ScopedProxyMode.INTERFACES);
+				case "no" -> scanner.setScopedProxyMode(ScopedProxyMode.NO);
+				default ->
+						throw new IllegalArgumentException("scoped-proxy only supports 'no', 'interfaces' and 'targetClass'");
 			}
 		}
 	}
@@ -234,28 +229,28 @@ public class ComponentScanBeanDefinitionParser implements BeanDefinitionParser {
 		String filterType = element.getAttribute(FILTER_TYPE_ATTRIBUTE);
 		String expression = element.getAttribute(FILTER_EXPRESSION_ATTRIBUTE);
 		expression = parserContext.getReaderContext().getEnvironment().resolvePlaceholders(expression);
-		if ("annotation".equals(filterType)) {
-			return new AnnotationTypeFilter((Class<Annotation>) ClassUtils.forName(expression, classLoader));
-		}
-		else if ("assignable".equals(filterType)) {
-			return new AssignableTypeFilter(ClassUtils.forName(expression, classLoader));
-		}
-		else if ("aspectj".equals(filterType)) {
-			return new AspectJTypeFilter(expression, classLoader);
-		}
-		else if ("regex".equals(filterType)) {
-			return new RegexPatternTypeFilter(Pattern.compile(expression));
-		}
-		else if ("custom".equals(filterType)) {
-			Class<?> filterClass = ClassUtils.forName(expression, classLoader);
-			if (!TypeFilter.class.isAssignableFrom(filterClass)) {
-				throw new IllegalArgumentException(
-						"Class is not assignable to [" + TypeFilter.class.getName() + "]: " + expression);
+		switch (filterType) {
+			case "annotation" -> {
+				return new AnnotationTypeFilter((Class<Annotation>) ClassUtils.forName(expression, classLoader));
 			}
-			return (TypeFilter) BeanUtils.instantiateClass(filterClass);
-		}
-		else {
-			throw new IllegalArgumentException("Unsupported filter type: " + filterType);
+			case "assignable" -> {
+				return new AssignableTypeFilter(ClassUtils.forName(expression, classLoader));
+			}
+			case "aspectj" -> {
+				return new AspectJTypeFilter(expression, classLoader);
+			}
+			case "regex" -> {
+				return new RegexPatternTypeFilter(Pattern.compile(expression));
+			}
+			case "custom" -> {
+				Class<?> filterClass = ClassUtils.forName(expression, classLoader);
+				if (!TypeFilter.class.isAssignableFrom(filterClass)) {
+					throw new IllegalArgumentException(
+							"Class is not assignable to [" + TypeFilter.class.getName() + "]: " + expression);
+				}
+				return (TypeFilter) BeanUtils.instantiateClass(filterClass);
+			}
+			default -> throw new IllegalArgumentException("Unsupported filter type: " + filterType);
 		}
 	}
 

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

@@ -61,22 +61,13 @@ public class ExecutorBeanDefinitionParser extends AbstractSingleBeanDefinitionPa
 			return;
 		}
 		String prefix = "java.util.concurrent.ThreadPoolExecutor.";
-		String policyClassName;
-		if (rejectionPolicy.equals("ABORT")) {
-			policyClassName = prefix + "AbortPolicy";
-		}
-		else if (rejectionPolicy.equals("CALLER_RUNS")) {
-			policyClassName = prefix + "CallerRunsPolicy";
-		}
-		else if (rejectionPolicy.equals("DISCARD")) {
-			policyClassName = prefix + "DiscardPolicy";
-		}
-		else if (rejectionPolicy.equals("DISCARD_OLDEST")) {
-			policyClassName = prefix + "DiscardOldestPolicy";
-		}
-		else {
-			policyClassName = rejectionPolicy;
-		}
+		String policyClassName = switch (rejectionPolicy) {
+			case "ABORT" -> prefix + "AbortPolicy";
+			case "CALLER_RUNS" -> prefix + "CallerRunsPolicy";
+			case "DISCARD" -> prefix + "DiscardPolicy";
+			case "DISCARD_OLDEST" -> prefix + "DiscardOldestPolicy";
+			default -> rejectionPolicy;
+		};
 		builder.addPropertyValue("rejectedExecutionHandler", new RootBeanDefinition(policyClassName));
 	}
 

spring-expression/src/test/java/org/springframework/expression/spel/SpelReproTests.java

@@ -1778,19 +1778,13 @@ class SpelReproTests extends AbstractExpressionTests {
 
 		@Override
 		public Object resolve(EvaluationContext context, String beanName) throws AccessException {
-			if (beanName.equals("foo")) {
-				return "custard";
-			}
-			else if (beanName.equals("foo.bar")) {
-				return "trouble";
-			}
-			else if (beanName.equals("&foo")) {
-				return "foo factory";
-			}
-			else if (beanName.equals("goo")) {
-				throw new AccessException("DONT ASK ME ABOUT GOO");
-			}
-			return null;
+			return switch (beanName) {
+				case "foo" -> "custard";
+				case "foo.bar" -> "trouble";
+				case "&foo" -> "foo factory";
+				case "goo" -> throw new AccessException("DONT ASK ME ABOUT GOO");
+				default -> null;
+			};
 		}
 	}
 

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

@@ -242,19 +242,17 @@ public abstract class JdbcUtils {
 			// Corresponding SQL types for JSR-310 / Joda-Time types, left up
 			// to the caller to convert them (e.g. through a ConversionService).
 			String typeName = requiredType.getSimpleName();
-			if ("LocalDate".equals(typeName)) {
-				return rs.getDate(index);
-			}
-			else if ("LocalTime".equals(typeName)) {
-				return rs.getTime(index);
-			}
-			else if ("LocalDateTime".equals(typeName)) {
-				return rs.getTimestamp(index);
-			}
+			return switch (typeName) {
+				case "LocalDate" -> rs.getDate(index);
+				case "LocalTime" -> rs.getTime(index);
+				case "LocalDateTime" -> rs.getTimestamp(index);
+				default ->
+
+					// Fall back to getObject without type specification, again
+					// left up to the caller to convert the value if necessary.
+						getResultSetValue(rs, index);
+			};
 
-			// Fall back to getObject without type specification, again
-			// left up to the caller to convert the value if necessary.
-			return getResultSetValue(rs, index);
 		}
 
 		// Perform was-null check if necessary (for results that the JDBC driver returns as primitives).

spring-web/src/main/java/org/springframework/web/context/request/FacesRequestAttributes.java

@@ -131,60 +131,26 @@ public class FacesRequestAttributes implements RequestAttributes {
 
 	@Override
 	public Object resolveReference(String key) {
-		if (REFERENCE_REQUEST.equals(key)) {
-			return getExternalContext().getRequest();
-		}
-		else if (REFERENCE_SESSION.equals(key)) {
-			return getExternalContext().getSession(true);
-		}
-		else if ("application".equals(key)) {
-			return getExternalContext().getContext();
-		}
-		else if ("requestScope".equals(key)) {
-			return getExternalContext().getRequestMap();
-		}
-		else if ("sessionScope".equals(key)) {
-			return getExternalContext().getSessionMap();
-		}
-		else if ("applicationScope".equals(key)) {
-			return getExternalContext().getApplicationMap();
-		}
-		else if ("facesContext".equals(key)) {
-			return getFacesContext();
-		}
-		else if ("cookie".equals(key)) {
-			return getExternalContext().getRequestCookieMap();
-		}
-		else if ("header".equals(key)) {
-			return getExternalContext().getRequestHeaderMap();
-		}
-		else if ("headerValues".equals(key)) {
-			return getExternalContext().getRequestHeaderValuesMap();
-		}
-		else if ("param".equals(key)) {
-			return getExternalContext().getRequestParameterMap();
-		}
-		else if ("paramValues".equals(key)) {
-			return getExternalContext().getRequestParameterValuesMap();
-		}
-		else if ("initParam".equals(key)) {
-			return getExternalContext().getInitParameterMap();
-		}
-		else if ("view".equals(key)) {
-			return getFacesContext().getViewRoot();
-		}
-		else if ("viewScope".equals(key)) {
-			return getFacesContext().getViewRoot().getViewMap();
-		}
-		else if ("flash".equals(key)) {
-			return getExternalContext().getFlash();
-		}
-		else if ("resource".equals(key)) {
-			return getFacesContext().getApplication().getResourceHandler();
-		}
-		else {
-			return null;
-		}
+		return switch (key) {
+			case REFERENCE_REQUEST -> getExternalContext().getRequest();
+			case REFERENCE_SESSION -> getExternalContext().getSession(true);
+			case "application" -> getExternalContext().getContext();
+			case "requestScope" -> getExternalContext().getRequestMap();
+			case "sessionScope" -> getExternalContext().getSessionMap();
+			case "applicationScope" -> getExternalContext().getApplicationMap();
+			case "facesContext" -> getFacesContext();
+			case "cookie" -> getExternalContext().getRequestCookieMap();
+			case "header" -> getExternalContext().getRequestHeaderMap();
+			case "headerValues" -> getExternalContext().getRequestHeaderValuesMap();
+			case "param" -> getExternalContext().getRequestParameterMap();
+			case "paramValues" -> getExternalContext().getRequestParameterValuesMap();
+			case "initParam" -> getExternalContext().getInitParameterMap();
+			case "view" -> getFacesContext().getViewRoot();
+			case "viewScope" -> getFacesContext().getViewRoot().getViewMap();
+			case "flash" -> getExternalContext().getFlash();
+			case "resource" -> getFacesContext().getApplication().getResourceHandler();
+			default -> null;
+		};
 	}
 
 	@Override

spring-web/src/main/java/org/springframework/web/util/TagUtils.java

@@ -67,18 +67,12 @@ public abstract class TagUtils {
 	 */
 	public static int getScope(String scope) {
 		Assert.notNull(scope, "Scope to search for cannot be null");
-		if (scope.equals(SCOPE_REQUEST)) {
-			return PageContext.REQUEST_SCOPE;
-		}
-		else if (scope.equals(SCOPE_SESSION)) {
-			return PageContext.SESSION_SCOPE;
-		}
-		else if (scope.equals(SCOPE_APPLICATION)) {
-			return PageContext.APPLICATION_SCOPE;
-		}
-		else {
-			return PageContext.PAGE_SCOPE;
-		}
+		return switch (scope) {
+			case SCOPE_REQUEST -> PageContext.REQUEST_SCOPE;
+			case SCOPE_SESSION -> PageContext.SESSION_SCOPE;
+			case SCOPE_APPLICATION -> PageContext.APPLICATION_SCOPE;
+			default -> PageContext.PAGE_SCOPE;
+		};
 	}
 
 	/**