diff --git a/spring-beans/src/main/java/org/springframework/beans/factory/support/RootBeanDefinition.java b/spring-beans/src/main/java/org/springframework/beans/factory/support/RootBeanDefinition.java
index 74fc92b97cb..b8183961870 100644
--- a/spring-beans/src/main/java/org/springframework/beans/factory/support/RootBeanDefinition.java
+++ b/spring-beans/src/main/java/org/springframework/beans/factory/support/RootBeanDefinition.java
@@ -508,7 +508,7 @@ public class RootBeanDefinition extends AbstractBeanDefinition {
 			}
 			if (this.externallyManagedInitMethods != null) {
 				for (String candidate : this.externallyManagedInitMethods) {
-					int indexOfDot = candidate.lastIndexOf(".");
+					int indexOfDot = candidate.lastIndexOf('.');
 					if (indexOfDot >= 0) {
 						String methodName = candidate.substring(indexOfDot + 1);
 						if (methodName.equals(initMethod)) {
@@ -585,7 +585,7 @@ public class RootBeanDefinition extends AbstractBeanDefinition {
 			}
 			if (this.externallyManagedDestroyMethods != null) {
 				for (String candidate : this.externallyManagedDestroyMethods) {
-					int indexOfDot = candidate.lastIndexOf(".");
+					int indexOfDot = candidate.lastIndexOf('.');
 					if (indexOfDot >= 0) {
 						String methodName = candidate.substring(indexOfDot + 1);
 						if (methodName.equals(destroyMethod)) {
diff --git a/spring-core/src/main/java/org/springframework/util/StringUtils.java b/spring-core/src/main/java/org/springframework/util/StringUtils.java
index 1b7a591faef..50014a3d665 100644
--- a/spring-core/src/main/java/org/springframework/util/StringUtils.java
+++ b/spring-core/src/main/java/org/springframework/util/StringUtils.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2021 the original author or authors.
+ * Copyright 2002-2022 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.
@@ -65,6 +65,8 @@ public abstract class StringUtils {
 
 	private static final String FOLDER_SEPARATOR = "/";
 
+	private static final char FOLDER_SEPARATOR_CHAR = '/';
+
 	private static final String WINDOWS_FOLDER_SEPARATOR = "\\";
 
 	private static final String TOP_PATH = "..";
@@ -568,7 +570,7 @@ public abstract class StringUtils {
 			return null;
 		}
 
-		int separatorIndex = path.lastIndexOf(FOLDER_SEPARATOR);
+		int separatorIndex = path.lastIndexOf(FOLDER_SEPARATOR_CHAR);
 		return (separatorIndex != -1 ? path.substring(separatorIndex + 1) : path);
 	}
 
@@ -589,7 +591,7 @@ public abstract class StringUtils {
 			return null;
 		}
 
-		int folderIndex = path.lastIndexOf(FOLDER_SEPARATOR);
+		int folderIndex = path.lastIndexOf(FOLDER_SEPARATOR_CHAR);
 		if (folderIndex > extIndex) {
 			return null;
 		}
@@ -609,7 +611,7 @@ public abstract class StringUtils {
 			return path;
 		}
 
-		int folderIndex = path.lastIndexOf(FOLDER_SEPARATOR);
+		int folderIndex = path.lastIndexOf(FOLDER_SEPARATOR_CHAR);
 		if (folderIndex > extIndex) {
 			return path;
 		}
@@ -626,11 +628,11 @@ public abstract class StringUtils {
 	 * @return the full file path that results from applying the relative path
 	 */
 	public static String applyRelativePath(String path, String relativePath) {
-		int separatorIndex = path.lastIndexOf(FOLDER_SEPARATOR);
+		int separatorIndex = path.lastIndexOf(FOLDER_SEPARATOR_CHAR);
 		if (separatorIndex != -1) {
 			String newPath = path.substring(0, separatorIndex);
 			if (!relativePath.startsWith(FOLDER_SEPARATOR)) {
-				newPath += FOLDER_SEPARATOR;
+				newPath += FOLDER_SEPARATOR_CHAR;
 			}
 			return newPath + relativePath;
 		}
diff --git a/spring-webmvc/src/test/java/org/springframework/web/servlet/tags/form/AbstractHtmlElementTagTests.java b/spring-webmvc/src/test/java/org/springframework/web/servlet/tags/form/AbstractHtmlElementTagTests.java
index 63cc5683921..4d2d4e50489 100644
--- a/spring-webmvc/src/test/java/org/springframework/web/servlet/tags/form/AbstractHtmlElementTagTests.java
+++ b/spring-webmvc/src/test/java/org/springframework/web/servlet/tags/form/AbstractHtmlElementTagTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2022 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.
@@ -135,7 +135,7 @@ public abstract class AbstractHtmlElementTagTests extends AbstractTagTests {
 	}
 
 	protected final void assertBlockTagContains(String output, String desiredContents) {
-		String contents = output.substring(output.indexOf(">") + 1, output.lastIndexOf("<"));
+		String contents = output.substring(output.indexOf(">") + 1, output.lastIndexOf('<'));
 		assertThat(contents.contains(desiredContents)).as("Expected to find '" + desiredContents + "' in the contents of block tag '" + output + "'").isTrue();
 	}