java - Can't write to external storage on Android

Question

I see a bunch of other people asking this same question, but none of the solutions posted helped me.

I'm trying to write a (binary) file to external storage from my Android app. I put <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" /> into my manifest, but I still can't manage to create any files. The code I'm using to create files is

File folder = new File(Environment.getExternalStorageDirectory(), SAVE_DIRECTORY);
File toWrite = new File(folder, "save.bin");
if(!toWrite.exists()){
    try {
        if(!folder.mkdirs())
            Log.e("Save", "Failed to create directories for save file!");
        toWrite.createNewFile();
     } catch (IOException e) {
         Log.e("Save", "Failed to create save file! " + e.getMessage());
     }
 }

The call to mkdirs() fails, and the createNewFile() throws the IOException (ENOENT, because the directory doesn't exist)

Anybody know what's up? I've even tried rebooting my device. I'm on API level 8 on a Nexus 7, if it makes any difference.

Answer 1

first you should check the ExternalStorageState

public static boolean isSDCARDAvailable(){
   return Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED);
}

if this method isSDCARDAvailable return true, then use your code

add the permissions:

<uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS" />