Kotlin How can I create a Directory. MkDir() is not working

Question

I am attempting to create a Directory for my apps data which will be .txt files. At this point, I don't care if it is on the Internal and or External Storage. I have been searching all over for a solution and I can't find anything that works. MkDir() or MKDirs() has not worked for me.

The code I have posted is just the first of many attempts to resolve this problem. I keep trying to change the directory path. It will Detect that existing paths are there but If I set it to the path I desire to create it will not work. I do have permission to read and write external storage in my Manifest I tried to find code to request permission at runtime with no success. So I manually allowed storage through the device's settings for the app and still nothing.

val f = File("/TestFolder")
        if (f.exists() && f.isDirectory()) {
            println("Exists")
        } else {
            f.mkdir()
            println("Does Not Exist.")
        }

user_8926845 · Answer

before you create file you should to create folder and thent create file in that please try as below

        val extStorageDirectory = Environment.getExternalStorageDirectory().toString()
        val dir = File(extStorageDirectory)
                if (!dir.exists())
                    dir.mkdirs()
                val file: File
                file = File(extStorageDirectory, "/TestFolder")

                if (file.exists()) {
                    file.delete()
                    file.createNewFile()
                } else {
                    file.createNewFile()
                }

alexey_r_9204 · Answer

The exact location of the where your files can be saved might vary across devices, so you should use the methods described on this page to access internal and external storage paths instead of using absolute file paths.

"/TestFolder" is an absolute path which is not part of external storage. It should be something like

val file = File(context.getExternalFilesDir(null), "TestFolder")
if (file.isDirectory()) { ... } else { 
    file.mkdirs()
    ...
}

(isDirectory implies exists so there's no need to check both).

Note also there is a distinction between private and public external storage (see https://developer.android.com/training/data-storage/files/external):

Public files: Files that should be freely available to other apps and to the user. When the user uninstalls your app, these files should remain available to the user. For example, photos captured by your app should be saved as public files.

Private files: Files stored in an app-specific directory—accessed using Context.getExternalFilesDir(). These files are cleaned up when the user uninstalls your app. Although these files are technically accessible by the user and other apps because they're on the external storage, they don't provide value to the user outside of your app. Use this directory for files that you don't want to share with other apps.

The above assumes you want a private directory.

user_11977220 · Answer

Hope this works:

var filename = "blesson.txt"

try {
    // create a File object for the parent directory
    val wallpaperDirectory = File("/sdcard/Wallpaper/")

    // have the object build the directory structure, if needed.
    wallpaperDirectory.mkdirs()

    // create a File object for the output file
    val outputFile = File(wallpaperDirectory, filename)

    // now attach the OutputStream to the file object, instead of a String representation
    val fos = FileOutputStream(outputFile)
} catch (e: FileNotFoundException) {
    e.printStackTrace()
}

Kotlin How can I create a Directory. MkDir() is not working

3 Answers