Scala:伴随对象和“新"对象关键词 [英] Scala: companion objects and "new" keyword

问题描述

在我最近有关在Scala中使用或省略新"关键字的帖子("new"关键字在Scala中)，我被告知忽略是由于某些类具有在其上使用apply方法定义的伴随对象的事实.我的问题是:我们是否能够分辨出或有任何通用规则来区分哪些类/对象具有伴随对象并应用方法?

预先感谢，很抱歉这是一个愚蠢的问题，但是来自Java背景，这有点令人困惑.

解决方案

在"new" keyword in Scala) I was told that the omission comes from the fact that certain classes have companion objects defined with apply method on them. My question is: are we able to tell or is there any general rule to distinguish which classes/objects have a companion object and apply method?

Thanks in advance and sorry of it's a stupid question, but coming from a Java background it is a bit confusing.

解决方案

In the Scala API documentation, you see a little icon in the list on the left side. If you click on that, you go to the documentation of the companion object of the class or trait that's mentioned.

Most of the collection classes and many other classes in the standard library have companion objects with apply methods.

For case classes, the Scala compiler automatically creates a companion object with an apply method (as well as other methods).

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