Android Tutorial [B4X] TextEditor - Save and load external files

Erel · Jul 20, 2021

This is a B4i and B4A example, which demonstrates various external files related tasks.

The behavior is not exactly the same as the platforms capabilities and behavior are different.

B4A

Load external files, including online files, using ContentChooser.
Save to an external target, using SaveAs: https://www.b4x.com/android/forum/t...list-of-other-related-methods.129897/#content
Allow other apps to view text files using this app : Receiving shared images from other apps
Extract information from the passed uri.

Note that no permission is needed. The minimum version was set to 7 (API 24), though it will probably work in older versions as well.
Don't miss the manifest editor additions and ime in the main module.

B4i

Load external files, including online files, using DocumentPickerViewController: https://www.b4x.com/android/forum/t...ments-with-documentpickerviewcontroller.99365
Share the text with ActivityViewController: https://www.b4x.com/android/forum/t...pp-with-activityviewcontroller.73159/#content
This also allows saving the text with the Files app.
Allow other apps to view text files using this app: https://www.b4x.com/android/forum/threads/open-external-files-with-your-app.50525/#content

Don't miss the main module PListExtra attributes and OpenUrl event.

A bit related B4J example: https://www.b4x.com/android/forum/threads/class-recent-files-manager.104633/post-822842

Updates:

- 9/2023 - Fixed an issue in B4A where overwriting existing files didn't trim file. Thanks @noeleon for reporting!

DonManfred · Feb 28, 2023

LucaMs said:
Done (now); it crashes.

Where is the code used and the full stacktrace? I don´t think anyone can help without.

LucaMs · Feb 28, 2023

DonManfred said:
Where is the code used and the full stacktrace? I don´t think anyone can help without.

The source code is in my post; also, it uses the FileHandler class which is part of the Erel's example project.
You can see the data of the selected file (log).
The only code that is missing is the one about the MediaPlayer:

B4X:

    mMediaPlayer.Load(Result.FileName, Result.RealName)
    mMediaPlayer.Play

I also tried:

B4X:

    mMediaPlayer.Load(Result.Dir, Result.RealName)
    mMediaPlayer.Play

although it seems to me that neither could have worked and indeed it is.

DIR: ContentDir
FN : content://com.android.providers.media.documents/document/audio%3A2247
RN : Dream_It_Possible.flac
Error occurred on line: 85 (B4XMainPage)
java.io.IOException: Prepare failed.: status=0x1
at android.media.MediaPlayer._prepare(Native Method)
at android.media.MediaPlayer.prepare(MediaPlayer.java:1313)
at anywheresoftware.b4a.objects.MediaPlayerWrapper.loadAfterReset(MediaPlayerWrapper.java:101)
at anywheresoftware.b4a.objects.MediaPlayerWrapper.Load(MediaPlayerWrapper.java:66)
at b4a.example.b4xmainpage$ResumableSub_pnlKey_LongClick.resume(b4xmainpage.java:274)
at anywheresoftware.b4a.shell.DebugResumableSub$DelegatableResumableSub.resumeAsUserSub(DebugResumableSub.java:48)
at java.lang.reflect.Method.invoke(Native Method)
at anywheresoftware.b4a.shell.Shell.runMethod(Shell.java:732)
at anywheresoftware.b4a.shell.Shell.raiseEventImpl(Shell.java:348)
at anywheresoftware.b4a.shell.Shell.raiseEvent(Shell.java:255)
at java.lang.reflect.Method.invoke(Native Method)
at anywheresoftware.b4a.ShellBA.raiseEvent2(ShellBA.java:157)
at anywheresoftware.b4a.BA.raiseEvent(BA.java:201)
at anywheresoftware.b4a.shell.DebugResumableSub$DelegatableResumableSub.resume(DebugResumableSub.java:43)
at anywheresoftware.b4a.BA.checkAndRunWaitForEvent(BA.java:275)
at anywheresoftware.b4a.ShellBA.raiseEvent2(ShellBA.java:150)
at anywheresoftware.b4a.BA.raiseEvent(BA.java:201)
at anywheresoftware.b4a.keywords.Common$15.run(Common.java:1804)
at android.os.Handler.handleCallback(Handler.java:808)
at android.os.Handler.dispatchMessage(Handler.java:101)
at android.os.Looper.loop(Looper.java:166)
at android.app.ActivityThread.main(ActivityThread.java:7529)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:245)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:921)

DonManfred · Feb 28, 2023

LucaMs said:
mMediaPlayer.Load(Result.FileName, Result.RealName)

looks wrong
If should be Result.Dir and Result.FileName

Path= ContentDir
filename: content://com.android.providers.media.documents/document/audio%3A2247

LucaMs · Feb 28, 2023

DonManfred said:
looks wrong
If should be Result.Dir and Result.FileName

Path= ContentDir
filename: content://com.android.providers.media.documents/document/audio%3A2247

Thanks, @DonManfred, so it works

[BTW Nice song, i didn't know i had ]

Erel · Sep 10, 2023

- 9/2023 - Fixed an issue in B4A where overwriting existing files didn't trim file. Thanks @noeleon for reporting!

The change is in FileHandler.SaveAs:

B4X:

Dim ContentResolver As JavaObject = ctxt.InitializeContext.RunMethodJO("getContentResolver", Null)
Dim out As OutputStream = ContentResolver.RunMethod("openOutputStream", Array(jo.RunMethod("getData", Null), "wt")) 'wt = Write+Trim

Juan Vargas (Bioagro) · Dec 15, 2023

If I could have a sample where I could save and restore a complete folder using this method, will be appreciated.

Erel · Dec 20, 2023

The user should have an option to overwrite an existing file. This is something that is controlled by the third party app that handles the "create document" intent.

papajds · Feb 3, 2024

Good morning,
what is the maximum size of a file that can be edited
THANKS

Erel · Feb 4, 2024

The focus of this example is the various ways to access external files/resources. The text editor itself is a regular multiline EditText. It will try to load the complete file into the text field.

If you want to edit large files then a more sophisticated approach is needed.

papajds · Feb 4, 2024

Ok, I'll try something else.
THANKS

Android Tutorial [B4X] TextEditor - Save and load external files

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