Replace isAssignableFrom() with isInstance() where feasible

framework-docs/modules/ROOT/pages/integration/jmx/notifications.adoc

@@ -32,7 +32,7 @@ example writes notifications to the console:
 		}
 
 		public boolean isNotificationEnabled(Notification notification) {
-			return AttributeChangeNotification.class.isAssignableFrom(notification.getClass());
+			return notification instanceof AttributeChangeNotification;
 		}
 
 	}

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

@@ -75,7 +75,7 @@ public void setThrowingName(String name) {
 	 * is only invoked if the thrown exception is a subtype of the given throwing type.
 	 */
 	private boolean shouldInvokeOnThrowing(Throwable ex) {
-		return getDiscoveredThrowingType().isAssignableFrom(ex.getClass());
+		return getDiscoveredThrowingType().isInstance(ex);
 	}
 
 }

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

@@ -159,7 +159,7 @@ public Object instantiate(RootBeanDefinition bd, @Nullable String beanName, Bean
 				return result;
 			}
 			catch (IllegalArgumentException ex) {
-				if (factoryBean != null && !factoryMethod.getDeclaringClass().isAssignableFrom(factoryBean.getClass())) {
+				if (factoryBean != null && !factoryMethod.getDeclaringClass().isInstance(factoryBean)) {
 					throw new BeanInstantiationException(factoryMethod,
 							"Illegal factory instance for factory method '" + factoryMethod.getName() + "'; " +
 									"instance: " + factoryBean.getClass().getName(), ex);

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

@@ -276,7 +276,7 @@ private Object instantiateUserDefinedStrategy(
 					strategyType.getName() + "]: a zero-argument constructor is required", ex);
 		}
 
-		if (!strategyType.isAssignableFrom(result.getClass())) {
+		if (!strategyType.isInstance(result)) {
 			throw new IllegalArgumentException("Provided class name must be an implementation of " + strategyType);
 		}
 		return result;

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

@@ -768,7 +768,7 @@ private static Field[] getDeclaredFields(Class<?> clazz) {
 	public static void shallowCopyFieldState(final Object src, final Object dest) {
 		Assert.notNull(src, "Source for field copy cannot be null");
 		Assert.notNull(dest, "Destination for field copy cannot be null");
-		if (!src.getClass().isAssignableFrom(dest.getClass())) {
+		if (!src.getClass().isInstance(dest)) {
 			throw new IllegalArgumentException("Destination class [" + dest.getClass().getName() +
 					"] must be same or subclass as source class [" + src.getClass().getName() + "]");
 		}

spring-expression/src/main/java/org/springframework/expression/spel/ast/OperatorInstanceof.java

@@ -72,7 +72,7 @@ public BooleanTypedValue getValueInternal(ExpressionState state) throws Evaluati
 			result = BooleanTypedValue.FALSE;  // null is not an instanceof anything
 		}
 		else {
-			result = BooleanTypedValue.forValue(rightClass.isAssignableFrom(leftValue.getClass()));
+			result = BooleanTypedValue.forValue(rightClass.isInstance(leftValue));
 		}
 		this.type = rightClass;
 		if (rightOperand instanceof TypeReference) {

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

@@ -78,7 +78,7 @@ public GeneratedKeyHolder(List<Map<String, Object>> keyList) {
 		Iterator<Object> keyIter = this.keyList.get(0).values().iterator();
 		if (keyIter.hasNext()) {
 			Object key = keyIter.next();
-			if (key == null || !(keyType.isAssignableFrom(key.getClass()))) {
+			if (key == null || !(keyType.isInstance(key))) {
 				throw new DataRetrievalFailureException(
 						"The generated key type is not supported. " +
 						"Unable to cast [" + (key != null ? key.getClass().getName() : null) +

spring-jdbc/src/test/java/org/springframework/jdbc/support/CustomSQLExceptionTranslatorRegistrarTests.java

@@ -45,11 +45,11 @@ void customErrorCodeTranslation() {
 
 		DataAccessException exFor4200 = sext.doTranslate("", "", new SQLException("Ouch", "42000", 42000));
 		assertThat(exFor4200).as("Should have been translated").isNotNull();
-		assertThat(BadSqlGrammarException.class.isAssignableFrom(exFor4200.getClass())).as("Should have been instance of BadSqlGrammarException").isTrue();
+		assertThat(exFor4200).isInstanceOf(BadSqlGrammarException.class);
 
 		DataAccessException exFor2 = sext.doTranslate("", "", new SQLException("Ouch", "42000", 2));
 		assertThat(exFor2).as("Should have been translated").isNotNull();
-		assertThat(TransientDataAccessResourceException.class.isAssignableFrom(exFor2.getClass())).as("Should have been instance of TransientDataAccessResourceException").isTrue();
+		assertThat(exFor2).isInstanceOf(TransientDataAccessResourceException.class);
 
 		DataAccessException exFor3 = sext.doTranslate("", "", new SQLException("Ouch", "42000", 3));
 		assertThat(exFor3).as("Should not have been translated").isNull();

spring-messaging/src/main/java/org/springframework/messaging/MessageHeaders.java

@@ -205,7 +205,7 @@ protected static IdGenerator getIdGenerator() {
 		if (value == null) {
 			return null;
 		}
-		if (!type.isAssignableFrom(value.getClass())) {
+		if (!type.isInstance(value)) {
 			throw new IllegalArgumentException("Incorrect type specified for header '" +
 					key + "'. Expected [" + type + "] but actual type is [" + value.getClass() + "]");
 		}

spring-messaging/src/main/java/org/springframework/messaging/handler/CompositeMessageCondition.java

@@ -57,7 +57,7 @@ public List<MessageCondition<?>> getMessageConditions() {
 	@SuppressWarnings("unchecked")
 	public <T extends MessageCondition<T>> T getCondition(Class<T> messageConditionType) {
 		for (MessageCondition<?> condition : this.messageConditions) {
-			if (messageConditionType.isAssignableFrom(condition.getClass())) {
+			if (messageConditionType.isInstance(condition)) {
 				return (T) condition;
 			}
 		}

spring-messaging/src/main/java/org/springframework/messaging/handler/annotation/reactive/HeadersMethodArgumentResolver.java

@@ -61,7 +61,7 @@ else if (MessageHeaderAccessor.class == paramType) {
 		}
 		else if (MessageHeaderAccessor.class.isAssignableFrom(paramType)) {
 			MessageHeaderAccessor accessor = MessageHeaderAccessor.getAccessor(message, MessageHeaderAccessor.class);
-			if (accessor != null && paramType.isAssignableFrom(accessor.getClass())) {
+			if (accessor != null && paramType.isInstance(accessor)) {
 				return accessor;
 			}
 			else {

spring-messaging/src/main/java/org/springframework/messaging/handler/annotation/support/HeadersMethodArgumentResolver.java

@@ -61,7 +61,7 @@ else if (MessageHeaderAccessor.class == paramType) {
 		}
 		else if (MessageHeaderAccessor.class.isAssignableFrom(paramType)) {
 			MessageHeaderAccessor accessor = MessageHeaderAccessor.getAccessor(message, MessageHeaderAccessor.class);
-			if (accessor != null && paramType.isAssignableFrom(accessor.getClass())) {
+			if (accessor != null && paramType.isInstance(accessor)) {
 				return accessor;
 			}
 			else {

spring-messaging/src/main/java/org/springframework/messaging/handler/annotation/support/MessageMethodArgumentResolver.java

@@ -74,7 +74,7 @@ public Object resolveArgument(MethodParameter parameter, Message<?> message) thr
 		Class<?> targetMessageType = parameter.getParameterType();
 		Class<?> targetPayloadType = getPayloadType(parameter, message);
 
-		if (!targetMessageType.isAssignableFrom(message.getClass())) {
+		if (!targetMessageType.isInstance(message)) {
 			throw new MethodArgumentTypeMismatchException(message, parameter, "Actual message type '" +
 					ClassUtils.getDescriptiveType(message) + "' does not match expected type '" +
 					ClassUtils.getQualifiedName(targetMessageType) + "'");

spring-messaging/src/main/java/org/springframework/messaging/support/AbstractHeaderMapper.java

@@ -95,7 +95,7 @@ protected String toHeaderName(String propertyName) {
 		if (value == null) {
 			return null;
 		}
-		if (!type.isAssignableFrom(value.getClass())) {
+		if (!type.isInstance(value)) {
 			if (logger.isDebugEnabled()) {
 				logger.debug("Skipping header '" + name + "': expected type [" + type + "], but got [" +
 						value.getClass() + "]");

spring-messaging/src/test/java/org/springframework/messaging/handler/annotation/reactive/PayloadMethodArgumentResolverTests.java

@@ -169,8 +169,7 @@ private DataBuffer toDataBuffer(String value) {
 
 		Object value = result.block(Duration.ofSeconds(5));
 		if (value != null) {
-			Class<?> expectedType = param.getParameterType();
-			assertThat(expectedType.isAssignableFrom(value.getClass())).as("Unexpected return value type: " + value).isTrue();
+			assertThat(value).isInstanceOf(param.getParameterType());
 		}
 		return (T) value;
 	}

spring-messaging/src/test/java/org/springframework/messaging/simp/SimpMessagingTemplateTests.java

@@ -164,7 +164,7 @@ void processHeadersToSend() {
 		Map<String, Object> map = this.messagingTemplate.processHeadersToSend(null);
 
 		assertThat(map).isNotNull();
-		assertThat(MessageHeaders.class.isAssignableFrom(map.getClass())).as("Actual: " + map.getClass()).isTrue();
+		assertThat(map instanceof MessageHeaders).as("Actual: " + map.getClass()).isTrue();
 
 		SimpMessageHeaderAccessor headerAccessor =
 				MessageHeaderAccessor.getAccessor((MessageHeaders) map, SimpMessageHeaderAccessor.class);

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

@@ -61,7 +61,7 @@ public static <T> T assertAndReturnModelAttributeOfType(ModelAndView mav, String
 			fail("Model attribute with name '" + modelName + "' is null");
 		}
 		assertTrue("Model attribute is not of expected type '" + expectedType.getName() + "' but rather of type '" +
-				obj.getClass().getName() + "'", expectedType.isAssignableFrom(obj.getClass()));
+				obj.getClass().getName() + "'", expectedType.isInstance(obj));
 		return (T) obj;
 	}
 

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

@@ -95,7 +95,7 @@ public static boolean hasAncestorOfType(Tag tag, Class<?> ancestorTagClass) {
 		}
 		Tag ancestor = tag.getParent();
 		while (ancestor != null) {
-			if (ancestorTagClass.isAssignableFrom(ancestor.getClass())) {
+			if (ancestorTagClass.isInstance(ancestor)) {
 				return true;
 			}
 			ancestor = ancestor.getParent();

spring-webflux/src/main/java/org/springframework/web/reactive/result/SimpleHandlerAdapter.java

@@ -36,7 +36,7 @@ public class SimpleHandlerAdapter implements HandlerAdapter {
 
 	@Override
 	public boolean supports(Object handler) {
-		return WebHandler.class.isAssignableFrom(handler.getClass());
+		return handler instanceof WebHandler;
 	}
 
 	@Override

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

@@ -65,10 +65,10 @@ public Mono<Object> resolveArgument(
 		// This is done to enable early argument resolution here. When the Mono actually
 		// completes it is replaced in the model with the actual value.
 
-		if (Mono.class.isAssignableFrom(errors.getClass())) {
+		if (errors instanceof Mono) {
 			return ((Mono<?>) errors).cast(Object.class);
 		}
-		else if (Errors.class.isAssignableFrom(errors.getClass())) {
+		else if (errors instanceof Errors) {
 			return Mono.just(errors);
 		}
 		else {

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

@@ -76,7 +76,7 @@ protected NamedValueInfo createNamedValueInfo(MethodParameter parameter) {
 								parameter.getGenericParameterType() + " doesn't support empty values.");
 				return toAdapter.fromPublisher(Mono.empty());
 			}
-			if (parameter.getParameterType().isAssignableFrom(value.getClass())) {
+			if (parameter.getParameterType().isInstance(value)) {
 				return value;
 			}
 			ReactiveAdapter fromAdapter = getAdapterRegistry().getAdapter(value.getClass());

spring-webflux/src/main/java/org/springframework/web/reactive/socket/server/support/WebSocketHandlerAdapter.java

@@ -99,7 +99,7 @@ public WebSocketService getWebSocketService() {
 
 	@Override
 	public boolean supports(Object handler) {
-		return WebSocketHandler.class.isAssignableFrom(handler.getClass());
+		return handler instanceof WebSocketHandler;
 	}
 
 	@Override

spring-webflux/src/test/java/org/springframework/web/reactive/result/method/annotation/HttpEntityMethodArgumentResolverTests.java

@@ -275,7 +275,7 @@ private <T> T resolveValue(ServerWebExchange exchange, ResolvableType type) {
 		Object value = result.block(Duration.ofSeconds(5));
 
 		assertThat(value).isNotNull();
-		assertThat(param.getParameterType().isAssignableFrom(value.getClass())).as("Unexpected return value type: " + value.getClass()).isTrue();
+		assertThat(param.getParameterType().isInstance(value)).as("Unexpected return value type: " + value.getClass()).isTrue();
 
 		return (T) value;
 	}

spring-webflux/src/test/java/org/springframework/web/reactive/result/method/annotation/MessageReaderArgumentResolverTests.java

@@ -295,7 +295,7 @@ private <T> T resolveValue(MethodParameter param, String body) {
 		Object value = result.block(Duration.ofSeconds(5));
 
 		assertThat(value).isNotNull();
-		assertThat(param.getParameterType().isAssignableFrom(value.getClass())).as("Unexpected return value type: " + value).isTrue();
+		assertThat(param.getParameterType().isInstance(value)).as("Unexpected return value type: " + value).isTrue();
 
 		return (T) value;
 	}

spring-webflux/src/test/java/org/springframework/web/reactive/result/method/annotation/RequestBodyMethodArgumentResolverTests.java

@@ -234,7 +234,7 @@ private <T> T resolveValue(MethodParameter param, String body) {
 		Object value = result.block(Duration.ofSeconds(5));
 
 		assertThat(value).isNotNull();
-		assertThat(param.getParameterType().isAssignableFrom(value.getClass()))
+		assertThat(param.getParameterType().isInstance(value))
 				.as("Unexpected return value type: " + value).isTrue();
 
 		//no inspection unchecked
@@ -248,7 +248,7 @@ private <T> T resolveValueWithEmptyBody(MethodParameter param) {
 		Object value = result.block(Duration.ofSeconds(5));
 
 		if (value != null) {
-			assertThat(param.getParameterType().isAssignableFrom(value.getClass()))
+			assertThat(param.getParameterType().isInstance(value))
 					.as("Unexpected parameter type: " + value).isTrue();
 		}
 

spring-webflux/src/test/java/org/springframework/web/reactive/result/method/annotation/RequestPartMethodArgumentResolverTests.java

@@ -300,7 +300,7 @@ private <T> T resolveArgument(MethodParameter param, MultipartBodyBuilder builde
 		Object value = result.block(Duration.ofSeconds(5));
 
 		assertThat(value).isNotNull();
-		assertThat(param.getParameterType().isAssignableFrom(value.getClass())).isTrue();
+		assertThat(param.getParameterType().isInstance(value)).isTrue();
 		return (T) value;
 	}
 

spring-webflux/src/test/java/org/springframework/web/reactive/result/method/annotation/WebSessionMethodArgumentResolverTests.java

@@ -68,13 +68,13 @@ void resolverArgument() {
 		param = this.testMethod.arg(Mono.class, WebSession.class);
 		actual = this.resolver.resolveArgument(param, context, exchange).block();
 		assertThat(actual).isNotNull();
-		assertThat(Mono.class.isAssignableFrom(actual.getClass())).isTrue();
+		assertThat(actual instanceof Mono).isTrue();
 		assertThat(((Mono<?>) actual).block()).isSameAs(session);
 
 		param = this.testMethod.arg(Single.class, WebSession.class);
 		actual = this.resolver.resolveArgument(param, context, exchange).block();
 		assertThat(actual).isNotNull();
-		assertThat(Single.class.isAssignableFrom(actual.getClass())).isTrue();
+		assertThat(actual instanceof Single).isTrue();
 		assertThat(((Single<?>) actual).blockingGet()).isSameAs(session);
 	}
 

spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/ReactiveTypeHandler.java

@@ -579,11 +579,11 @@ private ContextSnapshotHelper(@Nullable ContextSnapshotFactory factory) {
 
 		@SuppressWarnings("ReactiveStreamsUnusedPublisher")
 		public Object writeReactorContext(Object returnValue) {
-			if (Mono.class.isAssignableFrom(returnValue.getClass())) {
+			if (returnValue instanceof Mono) {
 				ContextSnapshot snapshot = this.snapshotFactory.captureAll();
 				return ((Mono<?>) returnValue).contextWrite(snapshot::updateContext);
 			}
-			else if (Flux.class.isAssignableFrom(returnValue.getClass())) {
+			else if (returnValue instanceof Flux) {
 				ContextSnapshot snapshot = this.snapshotFactory.captureAll();
 				return ((Flux<?>) returnValue).contextWrite(snapshot::updateContext);
 			}

spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/RequestResponseBodyAdviceChain.java

@@ -160,7 +160,7 @@ private <A> List<A> getMatchingAdvice(MethodParameter parameter, Class<? extends
 				}
 				advice = adviceBean.resolveBean();
 			}
-			if (adviceType.isAssignableFrom(advice.getClass())) {
+			if (adviceType.isInstance(advice)) {
 				result.add((A) advice);
 			}
 		}

spring-webmvc/src/test/java/org/springframework/web/servlet/ComplexWebApplicationContext.java

@@ -251,7 +251,7 @@ public int getOrder() {
 
 		@Override
 		public boolean supports(Object handler) {
-			return handler != null && MyHandler.class.isAssignableFrom(handler.getClass());
+			return handler instanceof MyHandler;
 		}
 
 		@Override
@@ -268,7 +268,7 @@ public static class MyDummyAdapter extends ApplicationObjectSupport implements H
 
 		@Override
 		public boolean supports(Object handler) {
-			return handler != null && MyHandler.class.isAssignableFrom(handler.getClass());
+			return handler instanceof MyHandler;
 		}
 
 		@Override

spring-websocket/src/main/java/org/springframework/web/socket/WebSocketExtension.java

@@ -103,7 +103,7 @@ public boolean equals(@Nullable Object other) {
 		if (this == other) {
 			return true;
 		}
-		if (other == null || !WebSocketExtension.class.isAssignableFrom(other.getClass())) {
+		if (other == null || !(other instanceof WebSocketExtension)) {
 			return false;
 		}
 		WebSocketExtension otherExt = (WebSocketExtension) other;