对“超级"感到困惑此Java示例中的关键字 [英] Confused about "super" keyword in this Java example

问题描述

在此示例中，位于Java网站的教程页面上.两个接口定义相同的默认方法startEngine().类FlyingCar实现两个接口，并且由于明显的冲突而必须重写startEngine().

In this example on java website's tutorial page. Two interfaces define the same default method startEngine(). A class FlyingCar implements both interfaces and must override startEngine() because of the obvious conflict.

public interface OperateCar {
    // ...
    default public int startEngine(EncryptedKey key) {
        // Implementation
    }
}
public interface FlyCar {
    // ...
    default public int startEngine(EncryptedKey key) {
        // Implementation
    }
}

public class FlyingCar implements OperateCar, FlyCar {
    // ...
    public int startEngine(EncryptedKey key) {
        FlyCar.super.startEngine(key);
        OperateCar.super.startEngine(key);
    }
}

我不明白为什么从FlyingCar中使用super来引用OperateCar和FlyCar接口中的startEngine()两个版本.据我了解，startEngine()在任何超类中均未定义，因此不应被视为驻留在其中.我也没有看到super与FlyingCar

I don't understand why, from FlyingCar, super is used to refer to both versions of startEngine() in OperateCar and FlyCar interfaces. As I understand it, startEngine() was not defined in any super class, therefore shouldn't be referred as resident in one. I also do not see any relationship between super and the two interfaces as implemented in FlyingCar

推荐答案

据我了解，startEngine()未在任何超类中定义，因此不应被视为驻留在其中.

As I understand it, startEngine() was not defined in any super class, therefore shouldn't be referred as resident in one.

是的，它已定义.这是默认的实现，例如:

Yes it was defined. It's the default implementation, for example:

public interface OperateCar {
    // ...
    default public int startEngine(EncryptedKey key) {
        // Implementation
    }
}

OperateCar.super.startEngine(key)将执行默认实现.

如果没有默认实现，则只是一个接口方法， 那么该语句就没有意义，因为该接口将不包含实现，例如:

If there was no default implementation, just an interface method, then the statement wouldn't make sense, as the interface wouldn't contain an implementation, like this:

public interface OperateCar {
    // ...
    int startEngine(EncryptedKey key);
}

---

我也没有看到在FlyingCar中实现的super和两个接口之间的任何关系

I also do not see any relationship between super and the two interfaces as implemented in FlyingCar

不确定我了解您的要求. super是在父接口中调用实现的方法. 没有super，就没有其他表达方式.

Not sure I understand what you're asking. super is a way to call the implementation in the parent interface. Without super, there's just no other way to express that.

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