Use String::isEmpty instead of "".equals(arg) when arg is not null

Author: rupertw

spring-beans/src/main/java/org/springframework/beans/propertyeditors/StringTrimmerEditor.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.
@@ -72,7 +72,7 @@ public void setAsText(@Nullable String text) {
 			if (this.charsToDelete != null) {
 				value = StringUtils.deleteAny(value, this.charsToDelete);
 			}
-			if (this.emptyAsNull && "".equals(value)) {
+			if (this.emptyAsNull && value.isEmpty()) {
 				setValue(null);
 			}
 			else {

spring-context/src/main/java/org/springframework/jndi/JndiTemplateEditor.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.
@@ -38,7 +38,7 @@ public void setAsText(@Nullable String text) throws IllegalArgumentException {
 		if (text == null) {
 			throw new IllegalArgumentException("JndiTemplate cannot be created from null string");
 		}
-		if ("".equals(text)) {
+		if (text.isEmpty()) {
 			// empty environment
 			setValue(new JndiTemplate());
 		}

spring-orm/src/main/java/org/springframework/orm/jpa/support/PersistenceAnnotationBeanPostProcessor.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.
@@ -472,7 +472,7 @@ protected EntityManagerFactory getPersistenceUnit(@Nullable String unitName) {
 				unitNameForLookup = this.defaultPersistenceUnitName;
 			}
 			String jndiName = this.persistenceUnits.get(unitNameForLookup);
-			if (jndiName == null && "".equals(unitNameForLookup) && this.persistenceUnits.size() == 1) {
+			if (jndiName == null && unitNameForLookup.isEmpty() && this.persistenceUnits.size() == 1) {
 				jndiName = this.persistenceUnits.values().iterator().next();
 			}
 			if (jndiName != null) {
@@ -505,7 +505,7 @@ protected EntityManager getPersistenceContext(@Nullable String unitName, boolean
 				unitNameForLookup = this.defaultPersistenceUnitName;
 			}
 			String jndiName = contexts.get(unitNameForLookup);
-			if (jndiName == null && "".equals(unitNameForLookup) && contexts.size() == 1) {
+			if (jndiName == null && unitNameForLookup.isEmpty() && contexts.size() == 1) {
 				jndiName = contexts.values().iterator().next();
 			}
 			if (jndiName != null) {

spring-test/src/main/java/org/springframework/test/web/servlet/htmlunit/MockMvcWebConnection.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.
@@ -110,7 +110,7 @@ public MockMvcWebConnection(MockMvc mockMvc, WebClient webClient, String context
 	 * @param contextPath the path to validate
 	 */
 	static void validateContextPath(@Nullable String contextPath) {
-		if (contextPath == null || "".equals(contextPath)) {
+		if (contextPath == null || contextPath.isEmpty()) {
 			return;
 		}
 		Assert.isTrue(contextPath.startsWith("/"), () -> "contextPath '" + contextPath + "' must start with '/'.");

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.
@@ -82,7 +82,7 @@ else if (urlPattern.endsWith(PATH_MAPPING_PATTERN)) {
 			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/WebUtils.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.
@@ -695,7 +695,7 @@ public static Map<String, Object> getParametersStartingWith(ServletRequest reque
 		}
 		while (paramNames != null && paramNames.hasMoreElements()) {
 			String paramName = paramNames.nextElement();
-			if ("".equals(prefix) || paramName.startsWith(prefix)) {
+			if (prefix.isEmpty() || paramName.startsWith(prefix)) {
 				String unprefixed = paramName.substring(prefix.length());
 				String[] values = request.getParameterValues(paramName);
 				if (values == null || values.length == 0) {