Can't create folder on external storage on android

Question

My development phone is a Nexus 5, running Android 4.4.2.

In my application, I am attempting to create a folder on external storage that wi

Answer 1

First, new File() is just create object for file connect.
you want use this file, file is exists or createNewFile().
If you want use this file to create directory, check file is exists, isDirectory() after then mkDir().
Second, check Environment.getExternalStorageDirectory is variable path.
You can use DDMS or ADB for work.
Additionaly, I think you add permission for read external storage for something error.

Answer 2

For Android 10+ add following into manifest:

<application
    android:requestLegacyExternalStorage="true"
    ...

as asking for Manifest.permission.WRITE_EXTERNAL_STORAGE is no more enough.