Usage of implements in java

implements can be used to implement classes or interfaces, requiring subclasses to override or implement methods in the parent class or interface. Specifically, they include: Implementing the interface: Subclasses must implement all methods in the interface. Inherited class: The subclass inherits all methods and properties of the parent class, but must implement all abstract methods in the parent class. Advantages of using implements: forced implementation of interface methods, flexibility of implementation classes, code reuse, loose coupling. Note: A subclass can only extend one class, but can implement multiple interfaces; it must implement all abstract methods in the interface; it is not necessary to implement non-abstract methods in the parent class.

Usage of implements in Java

implements are used to implement a class or interface. It specifies that a class or interface must implement or override a method declared in another class or interface.

Implementing the interface

When a class implements an interface, it must implement all methods declared in the interface. For example:

// 定义一个 Person 接口
interface Person {
    String getName();
}

// 实现 Person 接口
class Student implements Person {
    @Override
    public String getName() {
        return "John Doe";
    }
}

Inherited classes

When a class implements another class, it inherits all methods and properties of that class. But the difference is that the implementing class must implement all abstract methods declared in the parent class. For example:

// 定义一个 Shape 类
class Shape {
    protected String name;
}

// 实现 Shape 类
class Rectangle extends Shape {
    @Override
    public String getName() {
        return "Rectangle";
    }
}

Advantages of using implements

Using implements has the following advantages:

• Forced implementation of interface methods:It ensures that the implementation class provides All methods declared in the interface.
• Flexibility of implementation classes: It allows implementation classes to implement methods in their own way without following the specific implementation in the parent class or interface.
• Code Reuse: It allows implementing classes to reuse methods in interfaces or parent classes without having to implement them themselves.
• Loose coupling: It will reduce the degree of coupling between the implementation class and the interface or parent class, because the implementation class only focuses on the implementation method, regardless of the implementation of the interface or parent class.

Notes

You need to pay attention to the following points when using implements:

• A class can only extend one class, but can implements multiple interfaces.
• The implementation class must implement all abstract methods in the interface, otherwise a compilation error will occur.
• The implementation class does not need to implement the non-abstract method in the parent class unless it needs to override the method.

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