Java Messages Synchronous and Asynchronous

//The Consumer Class Consumes Messages in a Synchronous Manner

public class Consumer {
public static void main(String[] args) {
try {
// Gets the JNDI context
Context jndiContext = new InitialContext();
// Looks up the administered objects
ConnectionFactory connectionFactory = (ConnectionFactory) 
jndiContext.lookup("jms/javaee7/ConnectionFactory");
Destination queue = (Destination) jndiContext.lookup("jms/javaee7/Queue");
// Loops to receive the messages
try (JMSContext context = connectionFactory.createContext()) {
while (true) {
String message = context.createConsumer(queue).receiveBody(String.class);
}
}
} catch (NamingException e) {
e.printStackTrace();
}
}
}

//The Consumer Is a Message Listener

public class Listener implements MessageListener {
public static void main(String[] args) {
try {
// Gets the JNDI context
Context jndiContext = new InitialContext();
// Looks up the administered objects
ConnectionFactory connectionFactory = (ConnectionFactory) 
jndiContext.lookup("jms/javaee7/ConnectionFactory");
Destination queue = (Destination) jndiContext.lookup("jms/javaee7/Queue");
try (JMSContext context = connectionFactory.createContext()) {
context.createConsumer(queue).setMessageListener(new Listener());
}
} catch (NamingException e) {
e.printStackTrace();
}
}
public void onMessage(Message message) {
System.out.println("Async Message received: " + message.getBody(String.class));
}
}