Mar 11, 2025 · In Java, the difference between a class and an interface is syntactically similar; both contain methods and variables, but they are different in many aspects. The main difference is, A class defines the state of behaviour of objects. An interface defines the methods that a class must implement.

The interface keyword indicates that you are declaring a traditional interface class in Java. The @interface keyword is used to declare a new annotation type. See docs.oracle tutorial on annotations for a description of the syntax.

Mar 28, 2025 · The interface in Java is a mechanism to achieve abstraction. By default, variables in an interface are public, static, and final. It is used to achieve abstraction and multiple inheritance in Java. It supports loose coupling (classes depend on behavior, not implementation).

Mar 14, 2023 · In Java, an interface is a reference type similar to a class that can contain only constants, the method signatures, default methods, and static methods, and its Nested types. In interfaces, method bodies exist only for default methods and static methods. Writing an interface is similar to writing to a standard class.

Another way to achieve abstraction in Java, is with interfaces. An interface is a completely " abstract class " that is used to group related methods with empty bodies: To access the interface methods, the interface must be "implemented" (kinda like inherited) by another class with the implements keyword (instead of extends).

Jan 10, 2021 · Just as a counterpoint to this question: what is an interface in Java? An interface is a special form of an abstract class which does not implement any methods. In Java, you create an interface like this: void interfaceMethod();

In Java, an interface is declared using the interface keyword. Unlike a class, an interface cannot have instance variables or constructors, and all the methods declared in an interface are implicitly abstract (unless they are default or static methods).

Feb 25, 2025 · An interface cannot extend a class. The ‘implements’ part. An abstract class can implement multiple interfaces. An interface can implement multiple interfaces but does so by using the ‘extend’ keyword instead of ‘implements’. Initialization block ({}) An abstract class can have an initialization block which is inherited by subclasses.

Evolution of Interfaces in Java. The abstract class and interface difference in Java has narrowed over time with new Java versions: Traditional Interfaces (Before Java 8) Contained only abstract methods and constants; No method implementations; Java 8 Interfaces. Added default methods with implementations; Added static methods with implementations

Interfaces in Java are a fundamental part of object-oriented programming that help achieve abstraction and multiple inheritance. This article will explain what an interface is, how it works, and why it’s important. We’ll also explore its key features, advantages, and practical use cases to give you a clear understanding of interfaces in Java.