Loose vs Tight Coupling in Java: Key Differences & Examples

Coupling in Java refers to the degree of dependency between different classes, objects, or modules in a program. Understanding what is loose coupling and tight coupling in Java is essential for writing maintainable and scalable code. When components are loosely coupled in Java, they can be modified independently, promoting better flexibility and testability. In contrast, tight coupling in Java occurs when classes are highly dependent on one another, often leading to rigid and difficult-to-maintain code.

This article covers a deep dive into the concept of coupling in Java, exploring both loosely coupled and tightly coupled in Java systems with real-world examples. We’ll also compare loosely coupled vs tightly coupled scenarios, discuss design best practices, and help you understand how to build software architectures that are both robust and adaptable.

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What is Coupling in Java?

Coupling is nothing but the dependency of one class on the other. If one object in a code uses another object in the program, it is called loose coupling in Java. In coupling, two classes or objects collaborate and work with each other to complete a pre-defined task. It simply means that one element requires another element to complete a function. It is known as collaboration when one class calls the logic of the other class.

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What are the Types of Coupling?

Coupling in Java defines how closely classes or modules depend on each other, impacting software flexibility. Tight coupling in Java creates rigid dependencies, complicating changes, while loose coupling in Java fosters independence through abstractions, enhancing modularity. 

This section briefly outlines tight coupling and loose coupling in Java, comparing loosely coupled vs tightly coupled systems to clarify what is loose coupling and tight coupling in Java for better design decisions.

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1) Loose Coupling in Java

“What is loose coupling in Java?” Loose coupling in Java refers to a scenario where two classes, modules, or components have minimal dependencies on each other. It signifies that these classes are independent, with one class knowing only what the other exposes through its interfaces. In Java, loose coupling ensures that objects can be used externally when needed, promoting flexibility and easier maintenance in software development.

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Here, the parent object is rarely using the object, and the object can be easily changed from external sources. Loose coupling is generally considered best because it promotes flexibility, scalability, and easier maintenance by reducing dependencies between components, allowing for independent development and modification without impacting other parts of the system.

Example 1

Imagine you have created two classes, A and B, in your program. Class A is called volume, and class B evaluates the volume of a cylinder. If you change class A volume, then you are not forced to change class B. This is called loose coupling in Java. When class A requires changes in class B, then you have tight coupling.

Code

package loosecoupling;
 class Volume {
   public static void main(String args[]) {
        Cylinder b = new Cylinder(25, 25, 25);
           System.out.println(b.getVolume());
   }
}
final class Cylinder {
    private int volume;
    Cylinder(int length, int width, int height) {
             this.volume = length * width * height;
    }
    public int getVolume() {
             return volume;
    }
}

Explanation: In the above example, class A and class B are loosely coupled.

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Example 2

import java.io.IOException;
interface Food {
   public void display();
}
class Italian {
  Food s;
   public Italian(Food s){
   this.s = s;
   }
   public void display(){
      System.out.println("Italian");
      s.display();
   }
}
class Chinese implements Food {
   public Chinese(){}
   public void display(){
      System.out.println("Chinese");
   }
}
class Mexican implements Food {
   public Mexican(){}
   public void display(){
      System.out.println("Mexican");
   }
}
public class Test {
   public static void main(String args[]) throws IOException {
   Food b = new Chinese();
   Food c = new Mexican();
   Italian a = new Italian(b);
      //a.display() will print Italian and Chinese
      a.display();
   Italian a1 = new Italian(c);
      //a.display() will print Italian and Mexican
      a1.display();
   }
}

Output

Italian
Chinese
Italian
Mexican

Explanation: In the above example, all three classes are loosely coupled. It simply means that you can use the food interface to provide services by injecting any of the implemented services.

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2) Tight Coupling

When two classes are highly dependent on each other, it is called tight coupling. It occurs when a class takes too many responsibilities or where a change in one class requires changes in the other class. In tight coupling, an object (parent object) creates another object (child object) for its usage. If the parent object knows more about how the child object was implemented, we can say that the parent and child object are tightly coupled.

Example: 

Imagine you have created two classes A and B, in your program. Class A is called volume, and class B evaluates the volume of a cylinder. If you make any changes in the volume, then the same changes will reflect in class B. Hence, we can say both the classes are highly dependent on each other and are tightly coupled.

Code

package tightcoupling;

class Volume {
   public static void main(String args[]) {
        Cylinder b = new Cylinder(15, 15, 15);
           System.out.println(b.volume);
   }}
 class Cylinder {
   public int volume;
   Cylinder(int length, int width, int height) {
           this.volume = length * width * height;  }}

Output

3375

Explanation: In the above example, class A and class B are bound together and work with each other as a team.

Differences Between Loose Coupling and Tight Coupling

Coupling in Java determines how interconnected classes or modules are, directly affecting code maintainability and scalability. Tight coupling in Java binds classes to specific implementations, creating rigid dependencies, whereas loose coupling in Java uses abstractions like interfaces for flexibility. 

This table highlights key distinctions in loosely coupled vs tightly coupled systems, clarifying what is loose coupling and tight coupling in Java to guide better software design with tight coupling and loose coupling in Java.

Conclusion

In simple terms, choosing loose coupling over tight coupling in Java programming is a wise move. It brings significant advantages like flexibility, easier code reuse, and smooth change adaptability. With independent classes, modifying the code becomes a straightforward process, making testing more efficient. 

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