为什么我不能在接口中声明静态方法?

问题描述

这个话题说的最多 - 不能在接口中声明静态方法的原因是什么?

The topic says the most of it - what is the reason for the fact that static methods can't be declared in an interface?

public interface ITest {
    public static String test();
}

上面的代码给了我以下错误(至少在 Eclipse 中):接口方法 ITest.test() 的非法修饰符；只允许公共和抽象".

The code above gives me the following error (in Eclipse, at least): "Illegal modifier for the interface method ITest.test(); only public & abstract are permitted".

推荐答案

这里有几个问题.第一个是声明一个静态方法而不定义它的问题.这就是

There are a few issues at play here. The first is the issue of declaring a static method without defining it. This is the difference between

public interface Foo {
  public static int bar();
}

和

public interface Foo {
  public static int bar() {
    ...
  }
}

第一个是不可能的，原因是 Espo 提到:你不知道哪个实现类是正确的定义.

The first is impossible for the reasons that Espo mentions: you don't know which implementing class is the correct definition.

Java 可以允许后者；事实上，从 Java 8 开始，它确实如此！

Java could allow the latter; and in fact, starting in Java 8, it does!

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