B4A Class ExternalStorage - Access SD cards and USB sticks

Before we start:

1. External storage means a real sd card or a connected mass storage USB device.
2. This class can also be used to access the secondary storage (File.DirRootExternal). This becomes relevant with newer versions of Android that restrict direct access.
3. It has nothing to do with runtime permissions.
4. You can use RuntimePermissions.GetAllSafeDirsExternal to directly access a specific folder on the SD card.
5. You can use RuntimePermissions.GetSafeDirDefaultExternal to directly access a specific folder on the secondary storage.
6. The minimum version for this class is Android 5.

Starting from Android 4.4 it is no longer possible to directly access external storages.
The only way to access these storages is through the Storage Access Framework (SAF), which is a quite complex and under-documented framework.

The ExternalStorage class makes it simpler to work with SAF.

Usage:

1. Call ExternalStorage.SelectDir. This will open a dialog that will allow the user to select the root folder. Once selected the uri of the root folder is stored and can be later used without requiring the user to select the folder again. Even after the device is booted.

2. Wait For the ExternalFolderAvailable event.
Now you can access the files under Storage.Root, including inside subfolders.

3. Files are represented as a custom type named ExternalFile.

4. The following operations are supported: ListFiles, Delete, CreateNewFile, FindFile, OpenInputStream and OpenOutputStream.

See the attached example.

Depends on: ContentResolver and JavaObject libraries.
Add:

#AdditionalJar: com.android.support:support-core-utils

Updates

- V1.04: Packed as a b4xlib. New PreviousUriFileName field that can be used if you need multiple instances of ExternalStorages. This field defines the file where the URI will be written to for future uses.
- V1.03: New CreateDir and FindOrCreateDir subs. Thank you @ac9ts and @DonManfred.
- V1.02: Fix for issue related to the conversion of URIs to strings.
- V1.01: Fixes an issue with Storage.ListFiles. Credit goes to @agraham !

 

[Claudio Oliveira]

@Erel,

I'm trying your sample project "as is", and I'm getting this error.
Did I miss something?

B4A Version: 7.80
Parsing code. (0.01s)
Compiling code. (0.05s)
Compiling layouts code. (0.00s)
Organizing libraries. (0.00s)
Generating R file. Error
ERROR: In <declare-styleable> FontFamilyFont, unable to find attribute android:font
ERROR: In <declare-styleable> FontFamilyFont, unable to find attribute android:fontStyle
ERROR: In <declare-styleable> FontFamilyFont, unable to find attribute android:fontWeight

 

[Erel]

You should use a newer version of android.jar. Make sure to update it with B4A Sdk Manager and then configure it under Tools - Configure Paths.

 

[Claudio Oliveira]

Brilliant!
Thanks!

 

[RB Smissaert]

The posted project has a lot of files.
Would it be possible to condense all that in a library or add it to the Files library?

RBS

 

[DonManfred]

he posted project has a lot of files.
Would it be possible to condense all that in a library or add it to the Files library?

You are talking about WHICH FILES exactly? There is only ONE Classfile used.....
Additionally you should have started a NEW THREAD for your question.

 

[Meigionel TS]

How would you detect programmatically if a usb mass storage is attached to the device? Consider this scenario, I have used

storage.SelectDir(True)

where the directory I selected was of a usb mass storage, then I removed the mass storage, and try

Wait For Storage_ExternalFolderAvailable
    storage.CreateNewFile(storage.Root,"t" & Rnd(1,55555) & ".txt")

instead of throwing a new dialog to select a new path (because the old path no longer exists), it still uses the old path and does not throw any error.

This is a reason why I am looking for a way to detect if the usb mass storage is still there and if it is then use the previous path else ask user to select a new directory again.

 

[RB Smissaert]

> You are talking about WHICH FILES exactly?

All the files in the posted file ExternalStorage.zip.
As they were in the .zip I presumed they were somehow used.

RBS

 

[Erel]

ll the files in the posted file ExternalStorage.zip.
As they were in the .zip I presumed they were somehow used.

You only need to add the ExternalStorage class to your code.

instead of throwing a new dialog to select a new path (because the old path no longer exists), it still uses the old path and does not throw any error.

What is the output of CreateNewFile?

What happens if you try to list the files after the USB was removed?

 

[Meigionel TS]

What is the output of CreateNewFile

The program runs without throwing any error but since the path does not exists, no file is created anywhere.

What happens if you try to list the files after the USB was removed?

I get an null pointer exception (app crashes), and that is what I need to solve. If the user removes the usb storage, I need to detect the change and show a new dialog to select the path again. But I could not understand how to. :/

 

[Erel]

Catch the error with Try / Catch and know that there is no USB.

 

[Erel]

Example updated with a fix to the issue where the wrong image was shown. Thank you @Geezer!

 

[boon2]

error
#AdditionalJar: com.android.support:support-core-utils
1.i want link to download .jar
2.and save in where is folder
thanks.

 

[Erel]

Please post errors as text instead of a screenshot.

1.i want link to download .jar
2.and save in where is folder

There is no such thing.

You need to use B4A Sdk Manager. This resource is probably included in the recommended items list. If not then search for support-core-utils and install it.

 

[boon2]

Please post errors as text instead of a screenshot.

There is no such thing.

You need to use B4A Sdk Manager. This resource is probably included in the recommended items list. If not then search for support-core-utils and install it.

Thanks.

 

[boon2]

can't intall to samsung s3 android 4.3
sdk version 28

 

[Erel]

Please post the error message as text instead of screenshot.

 

[Johan Hormaza]

can't intall to samsung s3 android 4.3
sdk version 28
View attachment 71809

This message is because you had installed it on your cell phone, you must remove the previous installation and then try again or simply change the name of the package (Ctrl + B).

 

[Erel]

- V1.01: Fixes an issue with Storage.ListFiles. Credit goes to @agraham !

- V1.02 was also released with another bug fix.

 

[Erel]

- V1.03: New CreateDir and FindOrCreateDir subs. Thank you @ac9ts and @DonManfred.