Difference between Class and Interface in Java
When it comes to object-oriented programming (OOP) in the Java programming language, two important components are classes and interfaces. While they may have similar features, there are distinct differences between these two components. In this article, we will discuss the differences between class and interface in Java.
Class
A class is a blueprint or template for creating objects in Java. It defines the properties and behaviors of an object. A class can have various members such as fields, methods, constructors, static blocks, and nested classes.
Fields are variables that hold data, and methods define the behavior of an object. Constructors are special methods that are used to create objects, while static blocks are executed before the execution of main() method. Nested classes are classes within another class.
One key feature of classes is that they can be inherited, meaning that a subclass can inherit fields and methods from its superclass. Java supports single inheritance, which means that a class can only inherit from one superclass.
Interface
An interface is a collection of methods that an implementing class must provide. In other words, an interface is a contract that specifies the behavior of an object, but does not provide an implementation. An interface can have methods, default methods, static methods, and constant fields.
An interface does not have constructors or fields, and it cannot be instantiated like a class. A class can implement multiple interfaces, which allows for more flexibility in the design of an application.
One advantage of interfaces is that they can be used to achieve abstraction, which is an essential concept in OOP. Abstraction allows for the separation of interface from implementation, allowing for more flexibility in the design of an application.
Differences between Class and Interface
1. Implementation – A class provides the implementation of a set of related methods and fields, while an interface only defines the structure of the methods.
2. Inheritance – A class can be inherited, while an interface cannot.
3. Instantiation – A class can be instantiated and used to create objects, while an interface cannot be instantiated.
4. Multiple implementations – A class can only inherit from one superclass, while an interface can be implemented by multiple classes.
5. Default methods – An interface can have default methods, while a class cannot.
In conclusion, while classes and interfaces may have some similarities, they serve different purposes in Java programming. Classes provide the implementation of a set of related methods and fields, while interfaces define the structure of methods that a class must provide. Classes can be inherited and instantiated, while interfaces cannot. Therefore, when designing an application in Java, it is important to understand the differences between classes and interfaces and how to use them effectively.
Table difference between class and interface java
| Class | Interface |
|---|---|
| A class is a blueprint or template for creating objects that contain attributes and methods. | An interface is a collection of abstract methods that define a contract for implementing classes. |
| Classes can have attributes that represent the state of an object. | Interfaces can’t have instance variables, constructors, or static methods. |
| Classes can extend (inherit from) other classes. | Interfaces can extend multiple other interfaces. |
| Classes can be instantiated to create objects. | Interfaces can’t be instantiated, but they can be implemented by classes. |
| Classes can have public, private, and protected access modifiers. | Interfaces can only have public access modifiers. |
| Classes can have non-abstract methods that provide concrete implementations of behavior. | Interfaces can only have abstract methods that define behavior but don’t provide an implementation. |