Android Studio中@override的含义 [英] The Meaning of @override in Android Studio

问题描述

我是Android Studio的新手，我想知道Android Studio中 @Override 语句的用途。

I am completely new to Android Studio and I want to know the purpose of the @Override statement in Android Studio.

推荐答案

@Override是 Java注释。它告诉编译器以下方法覆盖其超类。例如，假设你实现了一个Person类。

@Override is a Java annotation. It tells the compiler that the following method overrides a method of its superclass. For instance, say you implement a Person class.

public class Person {
   public final String firstName;
   public final String lastName;

   //some methods

   @Override public boolean equals(Object other) {
      ...
   }
}

person类有一个equals（）方法。 equals方法已在Person的超类 Object <中定义/ A>。因此，equals（）的上述实现是对人员的equals（）的重新定义。也就是说，Person覆盖equals（）。

The person class has an equals() method. The equals method is already defined in Person's superclass Object. Therefore the above implementation of equals() is a redefinition of equals() for Persons. That is to say, Person overrides equals().

在没有明确注释方法的情况下覆盖方法是合法的。那么@Override注释有什么用呢？如果你不小心试图以这种方式覆盖equals（）怎么办：

It is legal to override methods without explicitly annotating it. So what is the @Override annotation good for? What if you accidentally tried to override equals() that way:

public boolean equals(Person other) {
   ...
}

上述情况有一个错误。你的意思是覆盖equals（），但你没有。为什么？因为真正的equals（）获取一个Object作为参数，你的equals（）获取一个Person作为参数。编译器不会告诉您有关该错误的信息，因为编译器不知道您想要覆盖。就编译器而言，您实际上意味着超载等于（ ）。但是如果你试图使用@Override注释覆盖equals：

The above case has a bug. You meant to override equals() but you didn't. Why? because the real equals() gets an Object as a parameter and your equals() gets a Person as a parameter. The compiler is not going to tell you about the bug because the compiler doesn't know you wanted to override. As far as the compiler can tell, you actually meant to overload equals(). But if you tried to override equals using the @Override annotation:

@Override public boolean equals(Person other) {
   ...
}

现在编译器知道你有错误。你想要覆盖，但你没有。因此，使用@Override注释的原因是显式声明方法覆盖。

Now the compiler knows that you have an error. You wanted to override but you didn't. So the reason to use the @Override annotation is to explicitly declare method overriding.

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