根据过滤器将数组分为两个 [英] Divide an Array into two according to a filter

问题描述

我的销售书籍的应用程序，当用户购买书籍时，会将pdf文件下载到手机的内存中.我有两类书籍，并且pdf文件的名称中有一个用于识别它的代码.

My app selling books, when a user buys a book, a pdf file is downloaded to the internal memory of the phone. I have two categories of books and the name of the pdf file has a code to identify it.

在所有已购买并因此下载的文件中，我具有以下代码来获取所有已购买书籍的数组:

Of all the files purchased and therefore downloaded, I have the following code to obtain an array of all the books purchased:

   val purchasedBooks: ArrayList<String> = ArrayList()

    val directoryFiles = context?.filesDir
    val files = directoryFiles?.listFiles()


    if (files != null) {
        for (aFile in files) {
            purchasedBooks.add(aFile.name)
        }
    }

此代码在purchasedBooks中返回我:

[ssbook1.pdf, ssbook2.pdf, ssbook3.pdf, aabook1.pdf, aabook2.pdf]

我需要这样:

val ssbooks = [ssbook1, ssbook2, ssbook3] // without .pdf
val aabooks = [aabook1, aabook2]

然后按部分在recyclerView中显示它:

To then show it in a recyclerView by sections:

________________
MY SS BOOK
________________
ssbook1
----------------
ssbook2
----------------
ssbook3
________________
MY AABOOK
________________
aabook1
----------------
aabook2

任何建议，我将不胜感激.

Any advice I will be grateful.

推荐答案

希望以下代码帮助.

val arr = listOf("ssbook1.pdf", "ssbook2.pdf", "ssbook3.pdf", "aabook1.pdf", "aabook2.pdf")
val result = arr.map {it.substringBefore(".pdf")}
                .groupBy {it.contains("ssbook")}
                .map { it.value}
println(result) // [[ssbook1, ssbook2, ssbook3], [aabook1, aabook2]]

您可以使用结果2D数组在回收站视图中显示部分

You can use the result 2D array to show sections in recycler view

这篇关于根据过滤器将数组分为两个的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！