Usage of interface in java

Answer: In Java, an interface defines a set of methods for classes to implement to achieve code reuse and loose coupling. An interface is declared using the interface keyword and contains method declarations but no implementations. A class implements an interface through implements and must implement all interface methods. Interfaces promote code reuse, loose coupling, and extensibility. Interfaces are used to define common behaviors, serve as contracts, and promote loose coupling between components. Interface methods cannot be implemented and are public and abstract by default. A class can implement multiple interfaces.

Usage of interface in Java

In Java, an interface is used to define a set of methods, which are composed of A class implementation that implements this interface. They are an important mechanism for achieving code reuse and loose coupling.

Declaration of interface

The interface is declared using the interface keyword. It is similar to a class declaration, but without method implementation:

<code class="java">public interface MyInterface {
    void doSomething();
}</code>

Methods in an interface are abstract by default, which means that they must be implemented by the class that implements the interface.

Implementing the interface

A class can implement the interface by using the implements keyword:

<code class="java">public class MyImplementation implements MyInterface {

    @Override
    public void doSomething() {
        // 方法实现
    }
}</code>

The class that implements the interface must implement all Declared interface method.

Advantages

• Code reuse: Interfaces allow multiple classes to share a set of methods, enabling code reuse and reducing copy-paste code.
• Loose coupling: Interface separates the definition of the interface from its implementation. Therefore, the implementation of an interface can be changed without changing the classes that depend on it.
• Extensibility: Interfaces allow new functionality to be easily added without changing existing classes. Just create a new class that implements the interface.

Usage scenarios

Interfaces are usually used in the following scenarios:

• Define common behaviors or operations that can be used in multiple Reuse within classes.
• As a contract, ensuring that the implemented class provides specific functionality.
• Promote loose coupling and scalability between components.

Notes

• The methods in the interface cannot be implemented.
• All methods in the interface are public and abstract by default.
• A class can implement multiple interfaces, separated by commas.

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