什么是“@ Override”在java中？ [英] What's "@Override" there for in java?

问题描述

public class Animal {
   public void eat() { System.out.println("I eat like a generic Animal."); }

}

public class Wolf extends Animal {
   @Override
   public void eat() { System.out.println("I eat like a wolf!"); }
}

@Override 实际上有一些功能，或者它只是有点评论？

Does @Override actually have some functionality or it's just kinda comment?

推荐答案

来自Java教程注释：

@Override - @Override 注释
通知编译器元素
是意味着覆盖在超类中声明的元素
（覆盖
方法将在名为接口和
继承的
课程中讨论。）

@Override — the @Override annotation informs the compiler that the element is meant to override an element declared in a superclass (overriding methods will be discussed in the the lesson titled "Interfaces and Inheritance").

   // mark method as a superclass method
   // that has been overridden
   @Override 
   int overriddenMethod() { }

虽然不需要使用t重写方法时，他的
注释，
有助于防止错误。如果标有 @Override 的
方法无法正确覆盖
其超类之一的方法，则编译器
生成错误。

While it's not required to use this annotation when overriding a method, it helps to prevent errors. If a method marked with @Override fails to correctly override a method in one of its superclasses, the compiler generates an error.

让我们看一下Java语言规范中给出的示例， 9.6.1.4覆盖。假设你要覆盖一个方法，等于，但是你写道：

Let's take a look at the example given in the Java Language specifications, 9.6.1.4 Override. Let's say you want to override a method, equals in that case, but you wrote:

    public boolean equals(Foo that) { ... }

而不是：

    public boolean equals(Object that) { ... }

虽然此代码合法，但使用 @Override 等于方法声明c $ c>会触发编译时错误，因为你实际上没有覆盖它，你正在重载它。这可能会导致令人讨厌的错误，覆盖注释类型有助于及早发现它们。

While this code is legal, annotating the equals method declaration with @Override would trigger a compile time error because you're in fact not overriding it, you're overloading it. This can cause nasty bugs and the Override annotation type helps at detecting them early.

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