listFiles() returns null on Android 6.0 emulator

Question

I want to read jpeg files from sdcard on Android 6.0 emulator, but file list returns null. The sample code can work on my phone:

            String sdcard =          


        

Answer 1

Your first call

if (permissionCheck1 != PackageManager.PERMISSION_GRANTED || permissionCheck2 != PackageManager.PERMISSION_GRANTED) {
    ActivityCompat.requestPermissions(this,
            new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE,
                         Manifest.permission.READ_EXTERNAL_STORAGE},
            REQUEST_READWRITE_STORAGE);
}

is to check if you have the permission. IF you don't have, the permission, callback is called. This is first time.

Subsequently, callback is not called since you already have the permission. So, your code should look like

if (permissionCheck1 != PackageManager.PERMISSION_GRANTED || permissionCheck2 != PackageManager.PERMISSION_GRANTED) {
    ActivityCompat.requestPermissions(this,
            new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE,
                         Manifest.permission.READ_EXTERNAL_STORAGE},
            REQUEST_READWRITE_STORAGE);
}
else
    finishCreationStep();