Kotlin recursively get size of a folder

Question

I have seen how to return size of a folder in Java: Get size of folder or file, but I couldn't find it in Kotlin.

How do I get the size of a folder in Kotlin?

Answer 1

To get the total size of files in the directory and its children, recursively, you can use the .walkTopDown() function to build a sequence that enumerates all of the files, and then sum the .lengths of its file elements.

val directory: File = ...

val totalSize = 
    directory.walkTopDown().filter { it.isFile }.map { it.length() }.sum()

Filtering the elements using .isFile is needed here because it is unspecified what .length returns when called on a File denoting a directory.

Answer 2

So here is how to do it :

private fun dirSize(dir: File): Long {

        if (dir.exists()) {
            var result: Long = 0
            val fileList = dir.listFiles()
            for (i in fileList!!.indices) {
                if (fileList[i].isDirectory) {
                    result += dirSize(fileList[i])
                } else {
                    result += fileList[i].length()
                }
            }
            return result
        }
        return 0
    }

And if you want a readable string your can do this :

private fun getStringSize(size: Long): String {
        if (size <= 0)
            return "0MB"
        val units = arrayOf("B", "KB", "MB", "GB", "TB")
        val digitGroups = (Math.log10(size.toDouble()) / Math.log10(1024.0)).toInt()
        return DecimalFormat("#,##0.#").format(size / Math.pow(1024.0, digitGroups.toDouble())) + " " + units[digitGroups]
    }

How to use it :

val directory = File(filesDir.absolutePath + File.separator + DIRECTORY_NAME)
println(getStringSize(dirSize(directory)))

Hope it's will help some of you.