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

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]

Done (now); it crashes.

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

 

[LucaMs]

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:

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

I also tried:

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

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

Spoiler: Log & error msg

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]

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]

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]

- 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:

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)]

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

 

[Erel]

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]

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

 

[Erel]

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]

Ok, I'll try something else.
THANKS

 

[ivan.tellez]

Tunning the example as is, it works if a file is selected directly in the Android chooser but if you select the "file from other apps", (for example a file explorer app like Solid explorer, My Files, Drive, etc) the app cant load the file.

This is shown in the Log:

Sub ExtractInformationFromURI

error extracting information from file provider

Error occurred on line: 63 (FileHandler)
java.lang.RuntimeException: Object should first be initialized (Cursor).
    at anywheresoftware.b4a.AbsObjectWrapper.getObject(AbsObjectWrapper.java:67)
    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.debug.Debug.delegate(Debug.java:262)
    at b4a.example.filehandler._extractinformationfromuri(filehandler.java:413)
    at b4a.example.filehandler$ResumableSub_Load.resume(filehandler.java:203)
    at anywheresoftware.b4a.shell.DebugResumableSub$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:351)
    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$DelegatableResumableSub.resume(DebugResumableSub.java:43)
    at anywheresoftware.b4a.BA.checkAndRunWaitForEvent(BA.java:275)
    at anywheresoftware.b4a.ShellBA.raiseEvent2(ShellBA.java:150)
    at anywheresoftware.b4a.BA.raiseEvent(BA.java:201)
    at anywheresoftware.b4a.phone.Phone$ContentChooser$1.ResultArrived(Phone.java:906)
    at anywheresoftware.b4a.BA$4.run(BA.java:593)
    at anywheresoftware.b4a.BA.setActivityPaused(BA.java:467)
    at b4a.example.main$ResumeMessage.run(main.java:313)
    at android.os.Handler.handleCallback(Handler.java:959)
    at android.os.Handler.dispatchMessage(Handler.java:100)
    at android.os.Looper.loopOnce(Looper.java:257)
    at android.os.Looper.loop(Looper.java:342)
    at android.app.ActivityThread.main(ActivityThread.java:9634)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:619)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:929)

Any Idea on how to improve the example?

 

[Erel]

Does it actually crash or this error is caught in the Catch block?
It is expected that ExtractInformationFromURI will not work in all cases.

 

[ivan.tellez]

Does it actually crash or this error is caught in the Catch block?

Right, it is caught in the Catch block.

Doing tests on other examples, looks like it needs the READ_EXTERNAL_STORAGE permission to open the file choosed using another app. I tried to implement CheckAndRequest but the dialog doesnt show and Result is allways false. Can you update the example to use READ_EXTERNAL_STORAGE ?

 

[Erel]

No such thing.

READ_EXTERNAL_STORAGE is no longer accepted by Android.

 

[ivan.tellez]

No such thing.

Right. I saw the "AudioChooseAndPlay" example but didnt notice it has a targetSdkVersion="28"...

In the "AudioChooseAndPlay" I saw this behavior. File is openned (either the audio or an xml) if choosed directly in the filechooser. But using another app as the source, the file will not open with the error described on #31. however, if the READ_EXTERNAL_STORAGE is used in that example, the file works...

In this text editor example we have the same behavior except that READ_EXTERNAL_STORAGE cant be used. So the question is, what is the equivalent to READ_EXTERNAL_STORAGE in targetSdkVersion="35" for openning a file returned from a provider app in the chooser?

 

[Erel]

The alternative is demonstrated in this example - ContentChooser. For further discussion please start a new thread.