Refine use of substring operations

Closes gh-25445

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

@@ -656,7 +656,7 @@ public class AspectJAdviceParameterNameDiscoverer implements ParameterNameDiscov
 				}
 
 				if (tokens[currentIndex].endsWith(")")) {
-					sb.append(tokens[currentIndex].substring(0, tokens[currentIndex].length() - 1));
+					sb.append(tokens[currentIndex], 0, tokens[currentIndex].length() - 1);
 					return new PointcutBody(numTokensConsumed, sb.toString().trim());
 				}
 

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

@@ -501,7 +501,7 @@ public class PropertyEditorRegistrySupport implements PropertyEditorRegistry {
 			if (endIndex != -1) {
 				String prefix = propertyPath.substring(0, startIndex);
 				String key = propertyPath.substring(startIndex, endIndex + 1);
-				String suffix = propertyPath.substring(endIndex + 1, propertyPath.length());
+				String suffix = propertyPath.substring(endIndex + 1);
 				// Strip the first key.
 				strippedPaths.add(nestedPath + prefix + suffix);
 				// Search for further keys to strip, with the first key stripped.

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

@@ -106,8 +106,8 @@ public class TaskExecutorFactoryBean implements
 				int maxPoolSize;
 				int separatorIndex = this.poolSize.indexOf('-');
 				if (separatorIndex != -1) {
-					corePoolSize = Integer.valueOf(this.poolSize.substring(0, separatorIndex));
-					maxPoolSize = Integer.valueOf(this.poolSize.substring(separatorIndex + 1, this.poolSize.length()));
+					corePoolSize = Integer.parseInt(this.poolSize.substring(0, separatorIndex));
+					maxPoolSize = Integer.parseInt(this.poolSize.substring(separatorIndex + 1));
 					if (corePoolSize > maxPoolSize) {
 						throw new IllegalArgumentException(
 								"Lower bound of pool-size range must not exceed the upper bound");

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2018 the original author or authors.
+ * Copyright 2002-2020 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.
@@ -199,7 +199,7 @@ public abstract class MimeTypeUtils {
 			throw new InvalidMimeTypeException(mimeType, "does not contain subtype after '/'");
 		}
 		String type = fullType.substring(0, subIndex);
-		String subtype = fullType.substring(subIndex + 1, fullType.length());
+		String subtype = fullType.substring(subIndex + 1);
 		if (MimeType.WILDCARD_TYPE.equals(type) && !MimeType.WILDCARD_TYPE.equals(subtype)) {
 			throw new InvalidMimeTypeException(mimeType, "wildcard type is legal only in '*/*' (all mime types)");
 		}

spring-jms/src/main/java/org/springframework/jms/listener/DefaultMessageListenerContainer.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2018 the original author or authors.
+ * Copyright 2002-2019 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.
@@ -309,7 +309,7 @@ public class DefaultMessageListenerContainer extends AbstractPollingMessageListe
 			int separatorIndex = concurrency.indexOf('-');
 			if (separatorIndex != -1) {
 				setConcurrentConsumers(Integer.parseInt(concurrency.substring(0, separatorIndex)));
-				setMaxConcurrentConsumers(Integer.parseInt(concurrency.substring(separatorIndex + 1, concurrency.length())));
+				setMaxConcurrentConsumers(Integer.parseInt(concurrency.substring(separatorIndex + 1)));
 			}
 			else {
 				setConcurrentConsumers(1);
@@ -383,8 +383,7 @@ public class DefaultMessageListenerContainer extends AbstractPollingMessageListe
 	public void setMaxConcurrentConsumers(int maxConcurrentConsumers) {
 		Assert.isTrue(maxConcurrentConsumers > 0, "'maxConcurrentConsumers' value must be at least 1 (one)");
 		synchronized (this.lifecycleMonitor) {
-			this.maxConcurrentConsumers =
-					(maxConcurrentConsumers > this.concurrentConsumers ? maxConcurrentConsumers : this.concurrentConsumers);
+			this.maxConcurrentConsumers = Math.max(maxConcurrentConsumers, this.concurrentConsumers);
 		}
 	}
 

spring-jms/src/main/java/org/springframework/jms/listener/SimpleMessageListenerContainer.java

@@ -108,7 +108,7 @@ public class SimpleMessageListenerContainer extends AbstractMessageListenerConta
 		try {
 			int separatorIndex = concurrency.indexOf('-');
 			if (separatorIndex != -1) {
-				setConcurrentConsumers(Integer.parseInt(concurrency.substring(separatorIndex + 1, concurrency.length())));
+				setConcurrentConsumers(Integer.parseInt(concurrency.substring(separatorIndex + 1)));
 			}
 			else {
 				setConcurrentConsumers(Integer.parseInt(concurrency));

spring-jms/src/main/java/org/springframework/jms/listener/endpoint/JmsActivationSpecConfig.java

@@ -226,7 +226,7 @@ public class JmsActivationSpecConfig {
 		try {
 			int separatorIndex = concurrency.indexOf('-');
 			if (separatorIndex != -1) {
-				setMaxConcurrency(Integer.parseInt(concurrency.substring(separatorIndex + 1, concurrency.length())));
+				setMaxConcurrency(Integer.parseInt(concurrency.substring(separatorIndex + 1)));
 			}
 			else {
 				setMaxConcurrency(Integer.parseInt(concurrency));

spring-messaging/src/main/java/org/springframework/messaging/simp/stomp/StompDecoder.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2020 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.
@@ -263,7 +263,7 @@ public class StompDecoder {
 		int index = inString.indexOf('\\');
 
 		while (index >= 0) {
-			sb.append(inString.substring(pos, index));
+			sb.append(inString, pos, index);
 			if (index + 1 >= inString.length()) {
 				throw new StompConversionException("Illegal escape sequence at index " + index + ": " + inString);
 			}

spring-messaging/src/main/java/org/springframework/messaging/simp/stomp/StompEncoder.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2017 the original author or authors.
+ * Copyright 2002-2020 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.
@@ -223,7 +223,7 @@ public class StompEncoder  {
 	private StringBuilder getStringBuilder(@Nullable StringBuilder sb, String inString, int i) {
 		if (sb == null) {
 			sb = new StringBuilder(inString.length());
-			sb.append(inString.substring(0, i));
+			sb.append(inString, 0, i);
 		}
 		return sb;
 	}

spring-test/src/main/java/org/springframework/test/web/servlet/setup/PatternMappingFilterProxy.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2019 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.
@@ -72,7 +72,7 @@ final class PatternMappingFilterProxy implements Filter {
 	private void addUrlPattern(String urlPattern) {
 		Assert.notNull(urlPattern, "Found null URL Pattern");
 		if (urlPattern.startsWith(EXTENSION_MAPPING_PATTERN)) {
-			this.endsWithMatches.add(urlPattern.substring(1, urlPattern.length()));
+			this.endsWithMatches.add(urlPattern.substring(1));
 		}
 		else if (urlPattern.equals(PATH_MAPPING_PATTERN)) {
 			this.startsWithMatches.add("");
@@ -82,7 +82,7 @@ final class PatternMappingFilterProxy implements Filter {
 			this.exactMatches.add(urlPattern.substring(0, urlPattern.length() - 2));
 		}
 		else {
-			if ("".equals(urlPattern)) {
+			if (urlPattern.isEmpty()) {
 				urlPattern = "/";
 			}
 			this.exactMatches.add(urlPattern);

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2017 the original author or authors.
+ * Copyright 2002-2019 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.
@@ -30,14 +30,19 @@ import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
 /**
- * Represents a URI template. A URI template is a URI-like String that contains variables
- * enclosed by braces ({@code {}}) which can be expanded to produce an actual URI.
+ * Representation of a URI template that can be expanded with URI variables via
+ * {@link #expand(Map)}, {@link #expand(Object[])}, or matched to a URL via
+ * {@link #match(String)}. This class is designed to be thread-safe and
+ * reusable, and allows any number of expand or match calls.
  *
- * <p>See {@link #expand(Map)}, {@link #expand(Object[])}, and {@link #match(String)}
- * for example usages.
- *
- * <p>This class is designed to be thread-safe and reusable, allowing for any number
- * of expand or match calls.
+ * <p><strong>Note:</strong> this class uses {@link UriComponentsBuilder}
+ * internally to expand URI templates, and is merely a shortcut for already
+ * prepared URI templates. For more dynamic preparation and extra flexibility,
+ * e.g. around URI encoding, consider using {@code UriComponentsBuilder} or the
+ * higher level {@link DefaultUriBuilderFactory} which adds several encoding
+ * modes on top of {@code UriComponentsBuilder}. See the
+ * <a href="https://docs.spring.io/spring/docs/current/spring-framework-reference/web.html#mvc-uri-building">reference docs</a>
+ * for further details.
  *
  * @author Arjen Poutsma
  * @author Juergen Hoeller
@@ -220,7 +225,7 @@ public class UriTemplate implements Serializable {
 								throw new IllegalArgumentException(
 										"No custom regular expression specified after ':' in \"" + variable + "\"");
 							}
-							String regex = variable.substring(idx + 1, variable.length());
+							String regex = variable.substring(idx + 1);
 							pattern.append('(');
 							pattern.append(regex);
 							pattern.append(')');

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2020 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.
@@ -245,12 +245,12 @@ public class RedirectView extends AbstractUrlBasedView {
 			String name = matcher.group(1);
 			Object value = (model.containsKey(name) ? model.get(name) : uriVariables.get(name));
 			Assert.notNull(value, () -> "No value for URI variable '" + name + "'");
-			result.append(targetUrl.substring(endLastMatch, matcher.start()));
+			result.append(targetUrl, endLastMatch, matcher.start());
 			result.append(encodeUriVariable(value.toString()));
 			endLastMatch = matcher.end();
 			found = matcher.find();
 		}
-		result.append(targetUrl.substring(endLastMatch, targetUrl.length()));
+		result.append(targetUrl.substring(endLastMatch));
 		return result;
 	}
 

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

@@ -277,7 +277,7 @@ public class UrlTag extends HtmlEscapingAwareTag implements ParamAware {
 			}
 			else {
 				if (this.context.endsWith("/")) {
-					url.append(this.context.substring(0, this.context.length() - 1));
+					url.append(this.context, 0, this.context.length() - 1);
 				}
 				else {
 					url.append(this.context);

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

@@ -56,7 +56,7 @@ import org.springframework.web.util.WebUtils;
  * but this behavior can be changed by overriding the
  * {@link #isEligibleProperty(String, Object)} method.
  *
- * <p>A URL for this view is supposed to be a HTTP redirect URL, i.e.
+ * <p>A URL for this view is supposed to be an HTTP redirect URL, i.e.
  * suitable for HttpServletResponse's {@code sendRedirect} method, which
  * is what actually does the redirect if the HTTP 1.0 flag is on, or via sending
  * back an HTTP 303 code - if the HTTP 1.0 compatibility flag is off.
@@ -386,7 +386,7 @@ public class RedirectView extends AbstractUrlBasedView implements SmartView {
 			if (value == null) {
 				throw new IllegalArgumentException("Model has no value for key '" + name + "'");
 			}
-			result.append(targetUrl.substring(endLastMatch, matcher.start()));
+			result.append(targetUrl, endLastMatch, matcher.start());
 			result.append(UriUtils.encodePathSegment(value.toString(), encodingScheme));
 			endLastMatch = matcher.end();
 		}

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

@@ -160,7 +160,7 @@ public class WebSocketExtension {
 				int eqIndex = parameter.indexOf('=');
 				if (eqIndex != -1) {
 					String attribute = parameter.substring(0, eqIndex);
-					String value = parameter.substring(eqIndex + 1, parameter.length());
+					String value = parameter.substring(eqIndex + 1);
 					parameters.put(attribute, value);
 				}
 			}