什么是Java的决赛在C＃中的相同呢？ [英] What is the equivalent of Java's final in C#?

问题描述

什么是Java的最后在C＃？

What is the equivalent of Java's final in C#?

推荐答案

最后 关键字在Java中几种用法。它对应于密封的两个 并 只读 在C＃中的关键字，这取决于的上下文中使用它。

The final keyword has several usages in Java. It corresponds to both the sealed and readonly keywords in C#, depending on the context in which it is used.

要prevent子类（继承自定义的类）：

To prevent subclassing (inheritance from the defined class):

的Java

public final class MyFinalClass {...}

C＃

public sealed class MyFinalClass {...}

方法

在虚拟方法prevent压倒一切的。

Methods

Prevent overriding of a virtual method.

的Java

public class MyClass
{
    public final void myFinalMethod() {...}
}

C＃

public class MyClass : MyBaseClass
{
    public sealed override void MyFinalMethod() {...}
}

由于约阿希姆绍尔指出，这两种语言之间有显着的区别就在这里是Java在默认情况下标记所有的非静态方法作为虚拟，而C＃将其标记为密封。因此，你只需要，如果你想停止已明确标记方法的另一个压倒一切的使用密封关键字在C＃虚拟中的基类。

As Joachim Sauer points out, a notable difference between the two languages here is that Java by default marks all non-static methods as virtual, whereas C# marks them as sealed. Hence, you only need to use the sealed keyword in C# if you want to stop further overriding of a method that has been explicitly marked virtual in the base class.

要只允许一个变量来分配一次：

To only allow a variable to be assigned once:

的Java

public final double pi = 3.14; // essentially a constant

C＃

public readonly double pi = 3.14; // essentially a constant

作为一个侧面说明，只读关键字不同于在的 常量 在除权pression关键字在评估的运行的而不是编译时间的，因此允许任意的前pressions。

As a side note, the effect of the readonly keyword differs from that of the const keyword in that the expression is evaluated at runtime rather than compile-time, hence allowing arbitrary expressions.

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