如何在Kotlin中使用多个比较字段按降序排序 [英] How to sort in descending order using multiple comparison fields in Kotlin

问题描述

Kotlin允许我使用多个比较字段对ASC和数组进行排序.

Kotlin allows me to sort ASC and array using multiple comparison fields.

例如:

return ArrayList(originalItems)
    .sortedWith(compareBy({ it.localHits }, { it.title }))

但是当我尝试对DESC(compareByDescending())进行排序时，它不允许我使用多个比较字段.

But when I try sort DESC (compareByDescending()), it does not allow me to use multiple comparison fields.

有什么办法可以做到吗?

Is there any way I can do it?

推荐答案

您可以使用thenByDescending()(或thenBy()升序)扩展功能来定义辅助Comparator.

You could use the thenByDescending() (or thenBy() for ascending order) extension function to define a secondary Comparator.

假设originalItems是SomeCustomObject，则类似这样的方法应该起作用:

Assuming originalItems are of SomeCustomObject, something like this should work:

return ArrayList(originalItems)
        .sortedWith(compareByDescending<SomeCustomObject> { it.localHits }
                .thenByDescending { it.title })

(当然，您必须用自己的通用类型替换SomeCustomObject)

(of course you have to replace SomeCustomObject with your own type for the generic)

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