Improve conditions for more code readability

* Reduce `else` condition
* Improve condition for returning type and avoiding NPE
* Polish diamond operator and pattern matching usage

Author: ngocnhan-tran1996

spring-amqp/src/main/java/org/springframework/amqp/core/Address.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2024 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.
@@ -16,6 +16,7 @@
 
 package org.springframework.amqp.core;
 
+import java.util.Objects;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
@@ -39,6 +40,7 @@
  * @author Dave Syer
  * @author Artem Bilan
  * @author Gary Russell
+ * @author Ngoc Nhan
  */
 public class Address {
 
@@ -111,21 +113,9 @@ public String getRoutingKey() {
 
 	@Override
 	public boolean equals(Object o) {
-		if (this == o) {
-			return true;
-		}
-		if (o == null || getClass() != o.getClass()) {
-			return false;
-		}
-
-		Address address = (Address) o;
-
-		return !(this.exchangeName != null
-				? !this.exchangeName.equals(address.exchangeName)
-				: address.exchangeName != null)
-				&& !(this.routingKey != null
-				? !this.routingKey.equals(address.routingKey)
-				: address.routingKey != null);
+		return o instanceof Address address
+				&& Objects.equals(this.exchangeName, address.exchangeName)
+				&& Objects.equals(this.routingKey, address.routingKey);
 	}
 
 	@Override

spring-amqp/src/main/java/org/springframework/amqp/core/Binding.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 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.
@@ -30,6 +30,7 @@
  * @author Mark Fisher
  * @author Dave Syer
  * @author Gary Russell
+ * @author Ngoc Nhan
  *
  * @see AmqpAdmin
  */
@@ -74,7 +75,7 @@ public Binding(@Nullable Queue lazyQueue, @Nullable String destination, Destinat
 			String exchange, @Nullable String routingKey, @Nullable Map<String, Object> arguments) {
 
 		super(arguments);
-		Assert.isTrue(lazyQueue == null || destinationType.equals(DestinationType.QUEUE),
+		Assert.isTrue(lazyQueue == null || destinationType == DestinationType.QUEUE,
 				"'lazyQueue' must be null for destination type " + destinationType);
 		Assert.isTrue(lazyQueue != null || destination != null, "`destination` cannot be null");
 		this.lazyQueue = lazyQueue;

spring-amqp/src/main/java/org/springframework/amqp/core/BindingBuilder.java

@@ -231,12 +231,12 @@ public static final class TopicExchangeRoutingKeyConfigurer extends AbstractRout
 
 		public Binding with(String routingKey) {
 			return new Binding(destination.queue, destination.name, destination.type, exchange, routingKey,
-					Collections.<String, Object>emptyMap());
+					Collections.emptyMap());
 		}
 
 		public Binding with(Enum<?> routingKeyEnum) {
 			return new Binding(destination.queue, destination.name, destination.type, exchange,
-					routingKeyEnum.toString(), Collections.<String, Object>emptyMap());
+					routingKeyEnum.toString(), Collections.emptyMap());
 		}
 	}
 
@@ -282,7 +282,7 @@ public Binding and(Map<String, Object> map) {
 		public Binding noargs() {
 			return new Binding(this.configurer.destination.queue,
 					this.configurer.destination.name, this.configurer.destination.type, this.configurer.exchange,
-					this.routingKey, Collections.<String, Object>emptyMap());
+					this.routingKey, Collections.emptyMap());
 		}
 
 	}
@@ -298,17 +298,17 @@ public static final class DirectExchangeRoutingKeyConfigurer extends AbstractRou
 
 		public Binding with(String routingKey) {
 			return new Binding(destination.queue, destination.name, destination.type, exchange, routingKey,
-					Collections.<String, Object>emptyMap());
+					Collections.emptyMap());
 		}
 
 		public Binding with(Enum<?> routingKeyEnum) {
 			return new Binding(destination.queue, destination.name, destination.type, exchange,
-					routingKeyEnum.toString(), Collections.<String, Object>emptyMap());
+					routingKeyEnum.toString(), Collections.emptyMap());
 		}
 
 		public Binding withQueueName() {
 			return new Binding(destination.queue, destination.name, destination.type, exchange, destination.name,
-					Collections.<String, Object>emptyMap());
+					Collections.emptyMap());
 		}
 
 	}

spring-amqp/src/main/java/org/springframework/amqp/support/converter/AbstractJavaTypeMapper.java

@@ -99,11 +99,9 @@ protected String retrieveHeader(MessageProperties properties, String headerName)
 	protected String retrieveHeaderAsString(MessageProperties properties, String headerName) {
 		Map<String, Object> headers = properties.getHeaders();
 		Object classIdFieldNameValue = headers.get(headerName);
-		String classId = null;
-		if (classIdFieldNameValue != null) {
-			classId = classIdFieldNameValue.toString();
-		}
-		return classId;
+		return classIdFieldNameValue != null
+				? classIdFieldNameValue.toString()
+				: null;
 	}
 
 	private void createReverseMap() {

spring-amqp/src/main/java/org/springframework/amqp/support/converter/ContentTypeDelegatingMessageConverter.java

@@ -109,9 +109,8 @@ protected MessageConverter getConverterForContentType(String contentType) {
 		if (delegate == null) {
 			throw new MessageConversionException("No delegate converter is specified for content type " + contentType);
 		}
-		else {
-			return delegate;
-		}
+
+		return delegate;
 	}
 
 }

spring-amqp/src/main/java/org/springframework/amqp/support/converter/MarshallingMessageConverter.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2024 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.
@@ -40,6 +40,7 @@
  * @author Arjen Poutsma
  * @author Juergen Hoeller
  * @author James Carr
+ * @author Ngoc Nhan
  * @see org.springframework.amqp.core.AmqpTemplate#convertAndSend(Object)
  * @see org.springframework.amqp.core.AmqpTemplate#receiveAndConvert()
  */
@@ -77,10 +78,9 @@ public MarshallingMessageConverter(Marshaller marshaller) {
 					"interface. Please set an Unmarshaller explicitly by using the " +
 					"MarshallingMessageConverter(Marshaller, Unmarshaller) constructor.");
 		}
-		else {
-			this.marshaller = marshaller;
-			this.unmarshaller = (Unmarshaller) marshaller;
-		}
+
+		this.marshaller = marshaller;
+		this.unmarshaller = (Unmarshaller) marshaller;
 	}
 
 	/**

spring-amqp/src/main/java/org/springframework/amqp/support/converter/MessagingMessageConverter.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2014-2020 the original author or authors.
+ * Copyright 2014-2024 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.
@@ -40,6 +40,7 @@
  * is considered to be a request).
  *
  * @author Stephane Nicoll
+ * @author Ngoc Nhan
  * @since 1.4
  */
 public class MessagingMessageConverter implements MessageConverter, InitializingBean {
@@ -104,11 +105,10 @@ public void afterPropertiesSet() {
 	public org.springframework.amqp.core.Message toMessage(Object object, MessageProperties messageProperties)
 			throws MessageConversionException {
 
-		if (!(object instanceof Message)) {
+		if (!(object instanceof Message<?> input)) {
 			throw new IllegalArgumentException("Could not convert [" + object + "] - only [" +
 					Message.class.getName() + "] is handled by this converter");
 		}
-		Message<?> input = (Message<?>) object;
 		this.headerMapper.fromHeaders(input.getHeaders(), messageProperties);
 		org.springframework.amqp.core.Message amqpMessage = this.payloadConverter.toMessage(
 				input.getPayload(), messageProperties);

spring-amqp/src/main/java/org/springframework/amqp/support/converter/RemoteInvocationResult.java

@@ -26,6 +26,7 @@
  *
  * @author Juergen Hoeller
  * @author Gary Russell
+ * @author Ngoc Nhan
  * @since 3.0
  */
 public class RemoteInvocationResult implements Serializable {
@@ -142,16 +143,13 @@ public boolean hasInvocationTargetException() {
 	@Nullable
 	public Object recreate() throws Throwable {
 		if (this.exception != null) {
-			Throwable exToThrow = this.exception;
-			if (this.exception instanceof InvocationTargetException invocationTargetException) {
-				exToThrow = invocationTargetException.getTargetException();
-			}
+			Throwable exToThrow = this.exception instanceof InvocationTargetException invocationTargetException
+					? invocationTargetException.getTargetException()
+					: this.exception;
 			RemoteInvocationUtils.fillInClientStackTraceIfPossible(exToThrow);
 			throw exToThrow;
 		}
-		else {
-			return this.value;
-		}
+		return this.value;
 	}
 
 }

spring-amqp/src/main/java/org/springframework/amqp/support/postprocessor/AbstractDecompressingPostProcessor.java

@@ -38,6 +38,7 @@
  * the final content encoding of the decompressed message.
  *
  * @author Gary Russell
+ * @author Ngoc Nhan
  * @since 1.4.2
  */
 public abstract class AbstractDecompressingPostProcessor implements MessagePostProcessor, Ordered {
@@ -115,9 +116,8 @@ public Message postProcessMessage(Message message) throws AmqpException {
 				throw new AmqpIOException(e);
 			}
 		}
-		else {
-			return message;
-		}
+
+		return message;
 	}
 
 	/**

spring-amqp/src/main/java/org/springframework/amqp/support/postprocessor/DelegatingDecompressingPostProcessor.java

@@ -98,22 +98,20 @@ public Message postProcessMessage(Message message) throws AmqpException {
 		if (encoding == null) {
 			return message;
 		}
-		else {
-			int delimAt = encoding.indexOf(':');
-			if (delimAt < 0) {
-				delimAt = encoding.indexOf(',');
-			}
-			if (delimAt > 0) {
-				encoding = encoding.substring(0, delimAt);
-			}
-			MessagePostProcessor decompressor = this.decompressors.get(encoding);
-			if (decompressor != null) {
-				return decompressor.postProcessMessage(message);
-			}
-			else {
-				return message;
-			}
+
+		int delimAt = encoding.indexOf(':');
+		if (delimAt < 0) {
+			delimAt = encoding.indexOf(',');
+		}
+		if (delimAt > 0) {
+			encoding = encoding.substring(0, delimAt);
 		}
+		MessagePostProcessor decompressor = this.decompressors.get(encoding);
+		if (decompressor != null) {
+			return decompressor.postProcessMessage(message);
+		}
+
+		return message;
 	}
 
 }