Java重写与重载：方法的‘改头换面’与‘改头换面’，必分清
Java中方法重载与重写是重要特性，初学者易混淆，核心区别如下： **方法重载（Overload）**：同一类中，方法名相同但参数列表不同（类型、数量或顺序），返回值、修饰符等可不同。目的是同一类中提供多参数处理方式（如计算器add方法支持不同参数相加），仅参数列表决定重载，返回值不同不算重载。 **方法重写（Override）**：子类对父类方法的重新实现，要求方法名、参数列表完全相同，返回值为父类返回值的子类，访问权限不低于父类。目的是子类扩展父类功能（如狗重写动物叫方法），静态方法不可重写（只能隐藏）。 **核心区别**：重载看参数不同（同一类），重写看继承（参数相同）。记住：重载“换参数”，重写“换实现”。
Read MoreJava Method Overriding: Subclasses Override Parent Class Methods to Implement Polymorphism Fundamentals
### Method Overriding: The Java Mechanism for Subclasses to "Modify" Parent Class Methods Method overriding is a Java mechanism where a subclass reimplements a parent class method while keeping the method declaration (such as name and parameter list) unchanged. It is used to extend the parent class's behavior and achieve code reuse. Four key rules must be followed: the method name and parameter list must be exactly the same; the return type must be a subclass of the parent class's return type (covariant); the access modifier must not be more restrictive than the parent class; and the exceptions thrown must be subclasses of the parent class's exceptions or fewer. For example, the `Animal` class defines a general `eat()` method. Subclasses `Dog` and `Cat` override this method to output "Dog eats bones" and "Cat eats fish" respectively, demonstrating different behaviors. This mechanism is the core of polymorphism: when a parent class reference points to a subclass object, the subclass's overridden method is automatically called at runtime, such as `Animal a = new Dog(); a.eat();` which outputs "Dog eats bones". It is important to distinguish method overriding from method overloading (Overload): Overriding occurs in subclasses and aims to modify the parent class's behavior, while overloading occurs in the same class with the same method name but different parameter lists, serving different parameter versions of the same function. Method overriding is crucial for code reuse and extension, as it preserves the parent class's framework while allowing subclasses to customize specific implementations.
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