📩 What is Messaging in OOP?
Messaging refers to objects communicating with each other by calling each other’s methods. In other words, one object sends a message to another object to request some behavior (or action).
🔗 Simple Definition
“Object A sends a message to Object B by calling a method on B.”
💬 Why is Messaging Important?
In OOP, objects don’t just sit there — they interact. This interaction happens through method calls, which is what we mean by “messaging.”
✅ This supports the core idea of encapsulation — objects don’t directly modify each other’s data; they only ask each other to perform actions (send messages).
✅ It helps you build loosely coupled systems, because objects don’t need to know each other’s internal details — just what messages they can send.
🔧 Example
Suppose we have two objects: User and EmailService
class User {
private String name;
private String email;
public User(String name, String email) {
this.name = name;
this.email = email;
}
public void notifyUser(EmailService emailService) {
String message = "Hello " + name + ", welcome to our platform!";
emailService.sendEmail(email, message); // This is messaging!
}
}
class EmailService {
public void sendEmail(String recipient, String message) {
System.out.println("Sending email to " + recipient + ": " + message);
}
}
Usage
User user = new User("Alice", "alice@example.com");
EmailService emailService = new EmailService();
user.notifyUser(emailService);
Explanation
✅ User object sends a message to the EmailService object asking it to send an email.
✅ User does not care how the email is sent (SMTP, API, etc.) — this is abstraction at work too.
🚀 In Short
🔗 Messaging = Calling methods between objects.
✅ It’s the backbone of how objects collaborate to solve problems in OOP.
⚠️ Bonus Fact
The term “messaging” actually comes from the very first object-oriented language, Smalltalk, where objects literally “sent messages” to each other (much like passing a note). Most modern OOP languages (like Java, Python, C++) don’t use this exact terminology, but the concept is still there — method calls between objects are messages.