繼承在Java中通過extends關(guān)鍵字實現(xiàn)，如class Dog extends Animal，使子類繼承父類的屬性和方法。其核心作用包括代碼復用、提升可維護性、建立類的層次結(jié)構(gòu)。 Java支持單繼承、多層繼承和層級繼承，但不直接支持多重繼承和混合繼承。使用時需注意方法重寫、調(diào)用父類構(gòu)造器、避免過度繼承。

Inheritance in Java is a mechanism where one class can inherit the properties and behaviors (fields and methods) of another class. This allows for code reuse and helps create a hierarchical structure between classes.

What does inheritance look like in code?

At its core, inheritance uses the extends keyword to let one class build on top of another.
For example:

 class Animal {
    void eat() {
        System.out.println("This animal eats food.");
    }
}

class Dog extends Animal {
    void bark() {
        System.out.println("The dog barks.");
    }
}

Here, the Dog class inherits the eat() method from the Animal class and adds its own bark() method.
You can then use them like this:

 Dog myDog = new Dog();
myDog.eat(); // Inherited from Animal
myDog.bark(); // Defined in Dog

This keeps your code organized and avoids duplication.

Why use inheritance?

There are a few practical reasons to use inheritance:

• Code Reuse : You don't have to rewrite common logic.
• Maintainability : If you need to change behavior, you only update it in one place.
• Hierarchical Organization : It reflects real-world relationships (eg, a Car and a Bike are both Vehicles ).

It's especially useful when building frameworks or large applications where consistency and structure matter.

Types of inheritance in Java

Java supports different types of inheritance, but some are restricted due to design choices:

• Single Inheritance : One subclass extends one superclass — fully supported.
• Multilevel Inheritance : A chain like A → B → C — also supported.
• Hierarchical Inheritance : One superclass with multiple subclasses — allowed.
• Multiple Inheritance : Not directly supported (you can't extend more than one class), but you can achieve similar results using interfaces.
• Hybrid Inheritance : A mix of the above — not supported directly either.

This limitation exists because Java wanted to avoid complexity and ambiguity that comes with multiple inheritance in languages like C .

Some things to keep in mind

• The child class can override methods from the parent class using the @Override annotation.
• Use super() to call the parent class constructor.
• Mark classes as final if you don't want them to be extended.
• Don't overdo it — deep inheritance chains can make code harder to read and maintain.

So while inheritance is powerful, it's best used thoughtfully.

基本上就這些。

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