Interface Vs Abstract Class In Different Languages

interface vs abstract class

There are some common types of questions asked during interviews. One of them is to say something about interface vs abstract class. In addition, they can request even which you would prefer one over the other. So, the topic is vital in case of a job or your project. 

By the way, you should know precisely when to use interfaces as well as when to use an abstract class during your application project. However, you may think that both are similar or almost similar. But there are some noticeable differences between them. Therefore, those differences will help you to select which one you should use where. 

So, here in this article, I am going to define each of them and their details. First of all, you are going to know the definitive interface and abstract class. Secondly, you will see the importance of them. Thirdly, I will present a differentiable chart. After that, I will help you know which one you should choose in different situations. 

And finally, I will go towards the conclusion before saying some additional information about the interface vs abstract class.


So, let’s get to know something about the interface and its behavior. By the way, here, we will learn about the definition of the interface and the reasons to use it. 

What is Interface

The interface is a thing we consider as a diagram to execute a class in a program. In addition, it has no any types of concrete ways to perform in your code. Besides, all kinds of ways you see in an interface are usually abstract methods

Therefore, you are never able to use the interface as a group. By the way, some kinds of classes can act in double methods that support the interface. In addition, you will never be able to use instance variables in the interface. However, you can form it as a public static final variable—for example, constant class variables. 

So, we usually can say that an interface will act as a behavioral contract among multiple procedures. 

Therefore, we have understood the concept of interface. If any of the classes work, an interface will guarantee and, of course, give some rules to all of its methods. In addition, all of the forms should be public as well as abstract in the interface. 

For Example,

public interface Movable 


    public void accelerate();

    public void decelerate();


public interface Drivable{

    public void drive();


Why Do We Use Interface

Here are some vital causes to use interfaces in your program. 

  • First of all, you can have abstraction by using an interface.
  • Secondly, an interface can help dynamic formulas to resolve at the run time. 
  • Thirdly, the interface can assist you to get loose coupling.
  • Finally, an interface will help you to distinguish the definition of the formula from the taken inheritance hierarchy. 

The interface has vast benefits in different programming languages. By the way, above, we discussed the crucial reasons to utilize in your program. 

Abstract Class

An abstract is a multi-purpose class to define and execute any program. So, an abstract class is able to describe necessary formulas for the concrete classes. In addition, it can support the execution of those formulas. 

However, if you want to utilize an abstract class, you should first move to the abstract class. Secondly, the abstract class will make all of the formulas described in an abstract. And that abstract is available inside the concrete class. 

By the way, let’s get into the definition of the abstract class below. 

What is Abstract Class

Abstract class possesses the abstract keyword in its statements, and that is the abstract class by definition. However, an abstract class must have at least one abstract formula. By the way, abstract class may have more than one concrete abstract.

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Moreover, an abstract class will always help you to make concrete classes. However, an inheriting class will always act for the abstract formula. And one more thing, the abstract class will never be instantiated.  

However, if we want to describe the abstract class with some execution, we will think that considering an interface might be the right choice. 

By the way, an abstract class may look like this: 

public conceptual class Vehicle {

   public void getReady(){

       System. Out. println(“I’m all set and ready to go”);


   public abstract void start();

   public abstract void stop();


Why Do We Use Abstract Class

Here are some vital causes to the use of an abstract class in your program. 


  • First of all, an abstract class will always present default functionality to its subclasses.


  • Secondly, it will offer a template for the specific classes.


  • Thirdly, the abstract class will assist us to describe some common types of interface for its subclasses. 


  • And finally, an abstract class will permit code reusability.


The above lists are the top reasons to use an abstract class on any program. However, both the interface and abstract class have their advantages. 

Difference Between Interface Vs, Abstract Class

If we want to state some abstract method, we can use both abstract class and interface. In addition, we use them to achieve abstraction. Besides, both can’t be instantiated. 


However, maybe some things are similar between them. But we also see some crucial differences between interface vs abstract class. So, let’s get into the details. 


Interface Abstract Class
The speed of the interface is comparatively slower than the abstract class.  Abstract classes have the right amount of speed. 
The interface can work with multiple inheritances.  Single inheritance. 
The interface contains abstract methods.  Abstract and concrete methods.
We can use it for future development.  Use it to avoid independence.
We do not see an interface containing data fields.  An abstract class can have data fields.
However, we can program interfaces using the keyword “implements.” Abstract classes usually use “extends.”
For Example: 

public interface Drawable{

Void draw();


For Example:

Public abstract class Shape{

Public abstract void draw();


Usability Between Interface Vs Abstract Class

If you want flexibility in your program, you should go for an abstract class. In addition, it has some concrete methods to derive the lessons to execute. On the other hand, when you decide to use an interface, you should work on all the formulas in a class that enlarges the interface. 


However, both are doing their best in terms of usability. By the way, an abstract class is always future-oriented. For example, you will need it whenever the future expansion is in the class hierarchy. On the other hand, you might need to expand the interface as well as make a new one if you want to give support for the future. 


By the way, you can attach a newer interface to your hierarchy whenever you need it. But it is impossible to add an extra abstract while you already have one.  For instance, you will be able to add an abstract class when you do not have one yet. 


You may input an interface program on a different note if you like a contract to the behavior and functionality. By the way, you cannot take an interface for writing a similar code on the interface formula. 


However, you can always use and reuse an abstract class to describe the methods in that case. So, you should utilize the interfaces for decoupling the code of the application from specific executions.  


Which One Should I Choose Between Interface Vs Abstract Class

If you ask me which one to choose between interface vs abstract class, it is difficult to answer. However, when we decide to supply some execution or requirement for a base class, an abstract class should be your first choice. 

For example, we might try to create some variables in a specific class to execute logic in an assistant formula. So, if you choose to apply to the abstract class, it will not be a bad option.

On the other hand, when you decide to implement some extra character for the classes, interfaces can be the right choice. By the way, you can execute similar functionality to apply both processes. 

However, whenever you consider writing code, the interface will help us perform abstraction and polymorphism. But these two are the main four object-oriented programming fundamentals. Besides, it can create to maintain some of your code lightly grouped instead of tightly grouped. 


So, you will get high-level modules that are dependent on the low-level modules. You can also utilize the interfaces to inject and create it more straightforward to try classes while checking. 

Extra Inquiry About Interface

Programmers always consider interfaces as a cool element for their program. Because it still provides some of the best functionality in the program. One of the significant aspects of interfaces is that they support more than one inheritance. 

Besides, you will get just a single static and final variable in the program’s interface. 

However, an interface is not only limited to those features. Also, it has more to make you amazed. So, it is not only for creating methods in your concrete classes. 

First of all, you are free to apply multiple interfaces at the same time. For example, you are working on an interface named Accounts_Delivarable. And that interface has some functions particular to Users that do not imply the Orders. 

Here is the program:


interface Accounts_Delivarable {

    public function creditCheck($varUserNumber);



Secondly, when you wish to apply this interface to Customers beside the Data_Interface, the program may look like this:

need_once (‘data_enters.php’);

so, need_once (‘data_interface.php’);

need_once (‘accounts_delivarable.php’);

class Users extends Data_Enters applies Data_Interface, Accounts_Delivarable {

So, you will slightly differ the interface title with some commas. By the way, we have got to know some valuable things from this program. For example, a customer may need to input the credit details in the function with some other requirements. 

Extra Inquiry About Abstract Class

You will see many differences between abstract class and interface while working on your program. However, the central contradiction between the two functions is that the abstract class can apply the code and expand them very well. 

By the way, there are other benefits to the abstract class. Such as it can possess the abstract method too. However, the plans have similarities with the interface because they both work under a function signature. In addition, they both need concrete classes to expand the abstract class in the right way. 


In addition, the abstract class will not use any kinds of abstract methods in our given instance. So, the Data_Entry class will not need to apply that method. 


Therefore, if you want, you can simply add some interface function in your abstract class program because abstract methods and others will be needed to expand classes.


However, you can relate this program as Data_Entry class:



abstract class Data_Entry {

so, abstract function putRecord();

abstract function removeRecord($varRecordId);


By the way, you can remove the two functions efficiently in the interface class. After that, the abstract class will force the putRecord and remove record to exist in the Users and Orders.

To Conclude interface vs abstract class,

The topic of interface vs abstract class is broad. Besides, it has excellent value in the programming community. However, the importance of interface is related to inserting the concrete classes. Besides, it applies all the formulas that are necessary by the interface. 


In addition, we may also inquire about our concrete classes to specify when we apply a unique interface. Besides, we can also execute various kinds of classes in multiple ways. So, the concrete classes are able to use on various interfaces. 


By the way, you need to know that the abstract class will also use abstract formulas to present a kind of plan that makes sure the rule. However, the abstract classes will move to the one pace ahead by giving class. Therefore, interface vs abstract class is strong and vital for programming. 


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