How to store files to a Specified External Directory in Android

Question

I am trying to copy some files from my Assets folder (and also create some new files) to an External folder.

I know that I will need following permissions -

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

Then, I should check for the External Storage state as following (code sample used from android's official example)-

/* Checks if external storage is available for read and write */
public boolean isExternalStorageWritable() {
    String state = Environment.getExternalStorageState();
    if (Environment.MEDIA_MOUNTED.equals(state)) {
        return true;
    }
    return false;
}

/* Checks if external storage is available to at least read */
public boolean isExternalStorageReadable() {
    String state = Environment.getExternalStorageState();
    if (Environment.MEDIA_MOUNTED.equals(state) ||
        Environment.MEDIA_MOUNTED_READ_ONLY.equals(state)) {
        return true;
    }
    return false;
}

Then, I can use getExternalFilesDir() as -

String finalOutputFilePath = context.getExternalFilesDir(null) + "/" + databaseName;

and it will save file to somewhere like - Android/data/myPackageName/files/

But, I want the files to be stored at a specific folder, for example -

• Create a folder, named "MyTestDirectory", if not already exists at the base of external storage (I am not writing sdcard/MyTestDirectory, as I read that external storage nomenclature may differ device to device) and
• Store/copy the files in that specific folder only

So, my question is how to select (create & use) the specified folder?

PS - I guess, this question might have already been answered on SO, but I couldn't find it.

Answer 1

To create folder use createFolder method.

private void createFolder(String folderName){
        File file=new File(Environment.getExternalStorageDirectory() + File.separator +folderName);
        if(!file.exists())
             file.mkdirs();
    } 


   private void CopyAssets(String folderName) {
            AssetManager assetManager = getAssets();
            String[] files = null;
            try {
                files = assetManager.list("Files");
            } catch (IOException e) {
                Log.e("tag", e.getMessage());
            }

            for(String filename : files) {
                System.out.println("File name => "+filename);
                InputStream in = null;
                OutputStream out = null;
                try {
                  in = assetManager.open("Files/"+filename);   // if files resides inside the "Files" directory itself
                  out = new FileOutputStream(Environment.getExternalStorageDirectory().toString()+File.separator +folderName +"/" + filename);
                  copyFile(in, out);
                  in.close();
                  in = null;
                  out.flush();
                  out.close();
                  out = null;
                } catch(Exception e) {
                    Log.e("tag", e.getMessage());
                }
            }
        }
        private void copyFile(InputStream in, OutputStream out) throws IOException {
            byte[] buffer = new byte[1024];
            int read;
            while((read = in.read(buffer)) != -1){
              out.write(buffer, 0, read);
            }
        }