在Java中使用Scala常数 [英] Use Scala constants in Java

问题描述

我目前正在为未来的项目评估Scala，遇到了一些奇怪的事情.我在JSP中为我们创建了以下常量:

I am currently evaluating Scala for future projects and came across something strange. I created the following constant for us in a JSP:

val FORMATED_TIME = "formatedTime";

它没有用.经过一些实验后，我决定进行反编译以了解其底部:

And it did not work. After some experimenting I decided to decompile to get to the bottom of it:

private final java.lang.String FORMATED_TIME;

public java.lang.String FORMATED_TIME();
  Code:
   0:   aload_0
   1:   getfield    #25; //Field FORMATED_TIME:Ljava/lang/String;
   4:   areturn

现在，这很有趣！就我个人而言，我已经想了好一阵子了，为什么Java中的检查员为什么需要前缀 get 和变量mutator前缀 set ，因为它们位于不同的命名空间中.

Now that is interesting! Personally I have been wondering for quite a while why an inspector needs the prefix get and a mutator the prefix set in Java as they live in different name-spaces.

但是，向团队其他成员解释这一点仍然很尴尬.那么有没有检查员的公共常量是可能的吗?

However it might still be awkward to explain that to the rest of the team. So is it possible to have a public constant without the inspector?

推荐答案

这是因为

This is because of the Uniform Access Principle, i.e.: Methods and Fields Are Indistinguishable

请参见此答案

在Scala 2.8.0中，这意味着您有 一个同伴对象，你会失去你的 静态转发器)

In Scala 2.8.0 this means if you have a companion object, you lose your static forwarders)

如果您在Scala中拥有此功能，

If you have this in Scala:

//Scala
object CommonControler {
      val FORMATED_TIME = "formatedTime";
}

您可以在Java中像这样使用它

You may use it like this from Java

//Java

// Variables become methods
CommonControler$.MODULE$.FORMATED_TIME();
// A static forwarder is avaliable
CommonControler.FORMATED_TIME();

另请参阅《 深度缩放》

还要注意 @ scala.reflect.BeanProperty 上课.

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