JAVA INTERFACE VS ABSTRACT CLASSES CODE

Useful for providing a partial implementation for reusing code. We’ve summarized these in the following tables, starting with abstract classes. Now we’ve covered the basics of what abstract classes and interfaces are, along with their differences, it’s time to move on to the advantages and drawbacks of each. Advantages and Disadvantages of Abstract Class vs.

JAVA INTERFACE VS ABSTRACT CLASSES CODE

In both cases, the goal is usually to make code more reusable, modular and flexible. When you need a class to implement several contracts, an interface is also preferable. However, if you want to define a contract and provide behavior for classes that aren’t as related, an interface is more appropriate. In addition to this, abstract classes are more useful when you plan on expanding the class further in the future, as new methods are easier to add than with interfaces. Abstract classes are more suited to providing an incomplete implementation or behavior to be inherited by multiple related classes. Ultimately, the decision to use either an abstract class or interface depends on the needs of your project and what you want to achieve. When Should Abstract Classes and Interfaces Be Used? This keeps the dependency of the classes on each other to a minimum. Interfaces also help to encourage loose coupling, since they give us a way for classes to interact based on guidelines rather than particular implementations. Abstract classes also enable this, however, since they provide a base class that can be inherited by multiple classes. This allows us to enable polymorphism, where we can treat objects as if they’re of the same class. In addition, abstract classes are used to achieve inheritance, as derived classes will inherit the properties from the abstract class.Īs mentioned before, the main purpose of interfaces is to provide a set of guidelines to classes. The functionality of the abstract methods is controlled by the abstract class, with subclasses providing a specific implementation. Because they lack implementation, abstract class methods are protected from being directly modified by external code.

There are many reasons to use both abstract classes and interfaces, but common ones are to enforce encapsulation, inheritance, polymorphism, and loose coupling. Their members are always public by default. Only one class can be extended from an abstract class.Ĭlasses can extend from multiple interfaces.Ĭan have protected, public or private members. Usually declared using the interface keyword.Ĭan contain either abstract or non-abstract methods. Usually declared with the abstract keyword. Used to provide contracts and functionality to classes.Ĭan’t be used to implement an abstract class. Used to provide properties and methods to derived classes to be overridden. You can refer to the table below for a summary of the key differences between abstract classes and interfaces. It should be noted that classes can only extend from one abstract class, but can extend from several interfaces at once. However, we can also implement interfaces via an abstract class, so that we can reuse the abstract method.

Many programming languages, such as Java, allow you to implement interfaces directly using the “interface” keyword.

Abstract classes do define a contract in a way, but they can also provide non-abstract methods. This can be thought of as similar to an abstract class, but interfaces can’t have non-abstract methods or member variables like abstract classes can. On the other hand, interfaces give a set of guidelines to a class, and can provide functionality, but they don’t contain any implementation. In this way, they serve as a kind of template or blueprint. The main objective of abstract classes is to provide properties and methods to be used by derived classes. You can think of abstract methods as similar to pure virtual functions in C++. those without implementation that must be overridden, they can also contain non-abstract methods. While abstract classes often contain abstract methods, i.e. Usually, we implement abstract classes with the “abstract” keyword and interfaces with the “interface” keyword. What’s the Difference Between an Abstract Class and an Interface?Īt a high level, an abstract class is one that we cannot instantiate on its own, and an interface is a contract of rules that a class must abide by.

Programmers often use these techniques to enforce encapsulation and share properties and behaviors among derived classes without having to repeat code. One of the main principles of Object-oriented programming (OOP) is the use of abstract classes and interfaces.

Java interface vs abstract classes