Replace 'String.length() == 0' with 'String.isEmpty()'

See gh-8103

spring-boot-actuator/src/main/java/org/springframework/boot/actuate/endpoint/ConfigurationPropertiesReportEndpoint.java

@@ -234,7 +234,7 @@ public class ConfigurationPropertiesReportEndpoint
 	private Map<String, Object> sanitize(String prefix, Map<String, Object> map) {
 		for (Map.Entry<String, Object> entry : map.entrySet()) {
 			String key = entry.getKey();
-			String qualifiedKey = (prefix.length() == 0 ? prefix : prefix + ".") + key;
+			String qualifiedKey = (prefix.isEmpty() ? prefix : prefix + ".") + key;
 			Object value = entry.getValue();
 			if (value instanceof Map) {
 				map.put(key, sanitize(qualifiedKey, (Map<String, Object>) value));

spring-boot-actuator/src/main/java/org/springframework/boot/actuate/endpoint/mvc/AbstractMvcEndpoint.java

@@ -69,7 +69,7 @@ public abstract class AbstractMvcEndpoint extends WebMvcConfigurerAdapter
 	@PostConstruct
 	private void validate() {
 		Assert.notNull(this.path, "Path must not be null");
-		Assert.isTrue(this.path.length() == 0 || this.path.startsWith("/"),
+		Assert.isTrue(this.path.isEmpty() || this.path.startsWith("/"),
 				"Path must start with / or be empty");
 	}
 

spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/amqp/RabbitProperties.java

@@ -770,7 +770,7 @@ public class RabbitProperties {
 			int hostIndex = input.indexOf("/");
 			if (hostIndex >= 0) {
 				this.virtualHost = input.substring(hostIndex + 1);
-				if (this.virtualHost.length() == 0) {
+				if (this.virtualHost.isEmpty()) {
 					this.virtualHost = "/";
 				}
 				input = input.substring(0, hostIndex);

spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/h2/H2ConsoleProperties.java

@@ -47,7 +47,7 @@ public class H2ConsoleProperties {
 	@PostConstruct
 	private void validate() {
 		Assert.notNull(this.path, "Path must not be null");
-		Assert.isTrue(this.path.length() == 0 || this.path.startsWith("/"),
+		Assert.isTrue(this.path.isEmpty() || this.path.startsWith("/"),
 				"Path must start with / or be empty");
 	}
 

spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/webservices/WebServicesProperties.java

@@ -44,7 +44,7 @@ public class WebServicesProperties {
 	@PostConstruct
 	private void validate() {
 		Assert.notNull(this.path, "Path must not be null");
-		Assert.isTrue(this.path.length() == 0 || this.path.startsWith("/"),
+		Assert.isTrue(this.path.isEmpty() || this.path.startsWith("/"),
 				"Path must start with / or be empty");
 	}
 

spring-boot-tools/spring-boot-loader/src/main/java/org/springframework/boot/loader/jar/AsciiBytes.java

@@ -121,7 +121,7 @@ final class AsciiBytes {
 	}
 
 	public AsciiBytes append(String string) {
-		if (string == null || string.length() == 0) {
+		if (string == null || string.isEmpty()) {
 			return this;
 		}
 		return append(string.getBytes(UTF_8));

spring-boot-tools/spring-boot-loader/src/main/java/org/springframework/boot/loader/jar/JarURLConnection.java

@@ -293,7 +293,7 @@ final class JarURLConnection extends java.net.JarURLConnection {
 		}
 
 		private String decode(String source) {
-			if (source.length() == 0 || (source.indexOf('%') < 0)) {
+			if (source.isEmpty() || (source.indexOf('%') < 0)) {
 				return source;
 			}
 			ByteArrayOutputStream bos = new ByteArrayOutputStream(source.length());
@@ -347,7 +347,7 @@ final class JarURLConnection extends java.net.JarURLConnection {
 		}
 
 		public boolean isEmpty() {
-			return this.name.length() == 0;
+			return this.name.isEmpty();
 		}
 
 		public String getContentType() {

spring-boot/src/main/java/org/springframework/boot/bind/RelaxedConversionService.java

@@ -120,7 +120,7 @@ class RelaxedConversionService implements ConversionService {
 
 			@Override
 			public T convert(String source) {
-				if (source.length() == 0) {
+				if (source.isEmpty()) {
 					// It's an empty enum identifier: reset the enum value to null.
 					return null;
 				}

spring-boot/src/main/java/org/springframework/boot/context/ConfigurationWarningsApplicationContextInitializer.java

@@ -206,14 +206,14 @@ public class ConfigurationWarningsApplicationContextInitializer
 		}
 
 		private boolean isProblematicPackage(String scannedPackage) {
-			if (scannedPackage == null || scannedPackage.length() == 0) {
+			if (scannedPackage == null || scannedPackage.isEmpty()) {
 				return true;
 			}
 			return PROBLEM_PACKAGES.contains(scannedPackage);
 		}
 
 		private String getDisplayName(String scannedPackage) {
-			if (scannedPackage == null || scannedPackage.length() == 0) {
+			if (scannedPackage == null || scannedPackage.isEmpty()) {
 				return "the default package";
 			}
 			return "'" + scannedPackage + "'";