# SelectFile library generates a “FATAL EXCEPTION: main” error

**URL:** <https://discourse.processing.org/t/selectfile-library-generates-a-fatal-exception-main-error/30175>\
**Category:** Processing for Android\
**Created:** [May 19, 2021, 6:50pm UTC](https://discourse.processing.org/t/selectfile-library-generates-a-fatal-exception-main-error/30175 "2021-05-19T18:50:20Z")\
**Posts on this page:** 20\
**Page:** 1

<div class="post-metadata">

**Author:** ![mmuylle](https://avatars.discourse-cdn.com/v4/letter/m/ea5d25/32.png) [@mmuylle](https://discourse.processing.org/u/mmuylle)\
**Post date:** [May 19, 2021, 6:50pm UTC](https://discourse.processing.org/t/selectfile-library-generates-a-fatal-exception-main-error/30175/1 "2021-05-19T18:50:20Z")

</div>

Running the example sketch (provided on the Processing website) “Select\_All\_Features” using the SelectFile library on my Android phone (Moto g7/Android 10) I get an error. When I tap one of the icons on the screen e.g. to open a folder etc, then the sketch crashes generating “FATAL EXCEPTION: main” error apparently for a "Attempt to get length of null array. Any suggestions to avoid this are welcome. Thanks.  
UPDATE: Even the most simple application of this library generates the error (see code and error console)

import select.files.\*;  
SelectLibrary files;

void setup() {  
fullScreen();

files = new SelectLibrary(this);

files.selectInput(“Select a file to process:”, “fileSelected”);  
// files.selectFolder(“Select a folder to process:”, “fileSelected”);  
// files.selectOutput(“Save the file please:”, “fileSelected”);  
}  
void fileSelected(File selection) {  
if (selection == null) {  
println(“Nothing was selected.”);  
} else {  
println("User selected " + selection.getAbsolutePath());  
}  
}

_BUILD SUCCESSFUL in 9s_  
_25 actionable tasks: 25 executed_  
_FATAL EXCEPTION: main_  
_Process: processing.test.test01, PID: 21829_  
_java.lang.NullPointerException: Attempt to get length of null array_

- at java.util.Arrays.sort(Arrays.java:1424)\*
- at select.files.SelectDialog.sortData(Unknown Source:2)\*
- at select.files.SelectDialog.getData(Unknown Source:17)\*
- at select.files.SelectDialog.updateCurrentList(Unknown Source:0)\*
- at select.files.SelectDialog.onCreate(Unknown Source:126)\*
- at android.app.Dialog.dispatchOnCreate(Dialog.java:421)\*
- at android.app.Dialog.show(Dialog.java:315)\*
- at select.files.SelectLibrary$1.run(Unknown Source:13)\*
- at android.os.Handler.handleCallback(Handler.java:883)\*
- at android.os.Handler.dispatchMessage(Handler.java:100)\*
- at android.os.Looper.loop(Looper.java:241)\*
- at android.app.ActivityThread.main(ActivityThread.java:7617)\*
- at java.lang.reflect.Method.invoke(Native Method)\*
- at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:492)\*
- at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:941)\*

---

<div class="post-metadata">

**Author:** ![paulgoux](https://avatars.discourse-cdn.com/v4/letter/p/b9bd4f/32.png) [@paulgoux](https://discourse.processing.org/u/paulgoux)\
**Post date:** [May 20, 2021, 12:05pm UTC](https://discourse.processing.org/t/selectfile-library-generates-a-fatal-exception-main-error/30175/2 "2021-05-20T12:05:38Z")

</div>

Not sure as i havent used the lib, here is an alternative though.

> [@fileInput class android, pick Folder or File](https://discourse.processing.org/t/fileinput-class-android-pick-folder-or-file/30148):
>
> Here is a class to handle file input in android. here is the base sketch; 
> 
> > **Summary**
> >
> > import android.app.Activity; import android.content.Intent; import processing.core.PApplet; import android.os.Bundle; import android.os.Environment; import android.content.Context; import android.provider.MediaStore; import android.net.Uri; import android.graphics.BitmapFactory; import android.database.Cursor; import android.os.Build.VERSION\_CODES; import android.os.Build; import android.graphics.Bitmap; fileInp…

---

<div class="post-metadata">

**Author:** ![mmuylle](https://avatars.discourse-cdn.com/v4/letter/m/ea5d25/32.png) [@mmuylle](https://discourse.processing.org/u/mmuylle)\
**Post date:** [May 21, 2021, 1:05pm UTC](https://discourse.processing.org/t/selectfile-library-generates-a-fatal-exception-main-error/30175/3 "2021-05-21T13:05:43Z")

</div>

Thank you for your suggestion, but for the moment I prefer to stick to the familiar field of processing examples.

---

<div class="post-metadata">

**Author:** ![paulgoux](https://avatars.discourse-cdn.com/v4/letter/p/b9bd4f/32.png) [@paulgoux](https://discourse.processing.org/u/paulgoux)\
**Post date:** [May 21, 2021, 5:45pm UTC](https://discourse.processing.org/t/selectfile-library-generates-a-fatal-exception-main-error/30175/4 "2021-05-21T17:45:20Z")

</div>

If you are on android selectinput and selectfolder do not work.

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<div class="post-metadata">

**Author:** ![mmuylle](https://avatars.discourse-cdn.com/v4/letter/m/ea5d25/32.png) [@mmuylle](https://discourse.processing.org/u/mmuylle)\
**Post date:** [May 25, 2021, 3:31pm UTC](https://discourse.processing.org/t/selectfile-library-generates-a-fatal-exception-main-error/30175/5 "2021-05-25T15:31:57Z")

</div>

Sorry for my late reply but can you please have a look at [SelectFile](https://andrusiv.com/android-select-file/) and then try to explain me why it does not work.  
Thanks

---

<div class="post-metadata">

**Author:** ![paulgoux](https://avatars.discourse-cdn.com/v4/letter/p/b9bd4f/32.png) [@paulgoux](https://discourse.processing.org/u/paulgoux)\
**Post date:** [May 25, 2021, 3:47pm UTC](https://discourse.processing.org/t/selectfile-library-generates-a-fatal-exception-main-error/30175/7 "2021-05-25T15:47:23Z")

</div>

Woops i thought you were referring to selectInput.

You are welcome to try it however i have never tried it.

However i have tried my lib, and am comfortable with the methods.

It is of course entirely up to you so feel free to use whatever you prefer.

---

<div class="post-metadata">

**Author:** ![paulgoux](https://avatars.discourse-cdn.com/v4/letter/p/b9bd4f/32.png) [@paulgoux](https://discourse.processing.org/u/paulgoux)\
**Post date:** [May 25, 2021, 3:57pm UTC](https://discourse.processing.org/t/selectfile-library-generates-a-fatal-exception-main-error/30175/8 "2021-05-25T15:57:46Z")

</div>

Please note that my lib also has a working text input class, called text area, ive made other posts on the forum if you want to see examples,

Also mine makes use of ala android file browser, and the only one ive found to be compatible is

File explorer by Xiaomi on the app store.

From the looks of things you probably have a problem as you havent set the permission requests in your sketch.

However the selectFile seems to have been made for an older version of android and its likely it wont work without choosing an alternative method for permission requests.

Please see their example sketch to see what i mean.

```auto
*
 * This minimalistic sketch shows how to use `selectFile()` on Android.
 * 
 * This sketch requires the READ_EXTERNAL_STORAGE permission to be selected
 * through the Sketch Permissions list in the PDE, and then to use the requestPermission()
 * function in the code, since READ_EXTERNAL_STORAGE is a dangerous permission that must
 * be requested during run-time in Android 23 and newer:
 * https://developer.android.com/guide/topics/permissions/requesting.html#normal-dangerous 
 */

import select.files.*;

SelectLibrary files;

void setup() {
  size(displayWidth, displayHeight);

  files = new SelectLibrary(this);
//these are the permissions you need but since api 28
//you have to request user input to confirm them. 
//The link i have provided should include a 
//permission class to address this problem.
  if (!hasPermission("android.permission.READ_EXTERNAL_STORAGE")) {
    requestPermission("android.permission.READ_EXTERNAL_STORAGE", "handleRequest");
  }

  // files.selectFolder("Select a folder to process:", "fileSelected");
  // files.selectOutput("Save the file please:", "fileSelected");
}

void handleRequest(boolean granted) {
  if (granted) {
    files.selectInput("Select a file to process:", "fileSelected");
  } else {
    println("Does not have permission to read external storage.");
  }
}

void fileSelected(File selection) {
  if (selection == null) {
    println("Nothing was selected.");
  } else {
    println("User selected " + selection.getAbsolutePath());
  }
}

```

---

<div class="post-metadata">

**Author:** ![mmuylle](https://avatars.discourse-cdn.com/v4/letter/m/ea5d25/32.png) [@mmuylle](https://discourse.processing.org/u/mmuylle)\
**Post date:** [May 27, 2021, 3:56pm UTC](https://discourse.processing.org/t/selectfile-library-generates-a-fatal-exception-main-error/30175/9 "2021-05-27T15:56:08Z")

</div>

Again sorry for a late answer, this is probably due to the fact that I am getting more and more frustrated with this problem which by the way I posted already 7 years ago on the predecessor of this forum. Any way, thank you for your help.  
The code you provided is the code that can be found on the Ostap Andrusiv page where you were so kind to comment on the importance of a proper handling of the permission requests. It is this code that I have tried several times (sorry the code at the top of my post is incomplete in that respect). Building the sketch works and a message appears on the phone asking to confirm the permissions set. Once accepted, the sketch will crash and the errors as mentioned above will appear.  
Have you successfully tried this code?  
regards  
marc

---

<div class="post-metadata">

**Author:** ![paulgoux](https://avatars.discourse-cdn.com/v4/letter/p/b9bd4f/32.png) [@paulgoux](https://discourse.processing.org/u/paulgoux)\
**Post date:** [May 27, 2021, 7:28pm UTC](https://discourse.processing.org/t/selectfile-library-generates-a-fatal-exception-main-error/30175/10 "2021-05-27T19:28:19Z")

</div>

not sure how the lib works honestly, and I don’t feel like digging around in it to understand why, as I currently have a working solution. Is it the best probably not, does it allow me to pick a file or a folder yes. Image text etc, no problem. Of course this is just my personal taste.

```auto

import select.files.*;

SelectLibrary files;

void setup() {
  size(displayWidth, displayHeight);
  Permission p = new Permission(this, "WRITE_EXTERNAL_STORAGE");
  p = new Permission(this, "READ_EXTERNAL_STORAGE");
  files = new SelectLibrary(this);

  //files.selectFolder("Select a folder to process:", "fileSelected");
  //files.selectOutput("Save the file please:", "fileSelected");
};

void mousePressed() {
  files.selectFolder("Select a folder to process:", "fileSelected");
  //selectInput("Select a file to process:", "fileSelected");
  files.selectOutput("Save the file please:", "fileSelected");
};

void handleRequest(boolean granted) {
  if (granted) {
    println("1");
    files.selectInput("Select a file to process:", "fileSelected");
  } else {
    println("Does not have permission to read external storage.");
  }
};

void fileSelected(File selection) {
  if (selection == null) {
    println("Nothing was selected.");
  } else {
    println("User selected " + selection.getAbsolutePath());
  }
};

```

this is the permission class remember you also need to set permission in processing’s ide.

```auto
public class Permission{
  
  PApplet parent;
  String p;

  public Permission(PApplet pParent,String permissionName) {
    parent = pParent;
    p = permissionName;
    parent.requestPermission("android.permission."+permissionName, "onPermissionResult", this);
  };

  public void onPermissionResult(boolean granted) {
    if (!granted) {
      PApplet.println("User did not grant", p ,"permission.", p ,"is disabled.");
    }
  };

};

```

However the code above doesnt work even with permissions.

---

<div class="post-metadata">

**Author:** ![mmuylle](https://avatars.discourse-cdn.com/v4/letter/m/ea5d25/32.png) [@mmuylle](https://discourse.processing.org/u/mmuylle)\
**Post date:** [August 9, 2021, 3:59pm UTC](https://discourse.processing.org/t/selectfile-library-generates-a-fatal-exception-main-error/30175/11 "2021-08-09T15:59:40Z")

</div>

Hi Paul,  
Better late than never I decided to try the code above you posted some time ago. All went well until the actual selection of a file. The sketch opened the build-in android fileselector on the phone and I could easily navigate to whatever file on the internal and external storage. The files were visible as thumbnail or as list but they were all greyed out. So it is not possible to make a selection. I checked to permissions but there all was fine. I noticed in the error console the following statements:  
The method getExternalStorageDirectory() from the type Environment is deprecated (line 62)  
The MediaStore.MediaColumns.DATA is deprecated. (line 135)  
Googeling the first statement I found that getExternalStorageDirectory() could be replaced by Context.getExternalFilesDir().getAbsolutePath();  
Unfortunately this creates another error. Regrettably my understanding of Java is rather primitive which means I cannot solve this myself. Can you please help me.  
regards, marc

---

<div class="post-metadata">

**Author:** ![paulgoux](https://avatars.discourse-cdn.com/v4/letter/p/b9bd4f/32.png) [@paulgoux](https://discourse.processing.org/u/paulgoux)\
**Post date:** [August 9, 2021, 4:30pm UTC](https://discourse.processing.org/t/selectfile-library-generates-a-fatal-exception-main-error/30175/12 "2021-08-09T16:30:30Z")

</div>

You’ll have to give me a few minutes.

---

<div class="post-metadata">

**Author:** ![paulgoux](https://avatars.discourse-cdn.com/v4/letter/p/b9bd4f/32.png) [@paulgoux](https://discourse.processing.org/u/paulgoux)\
**Post date:** [August 9, 2021, 6:26pm UTC](https://discourse.processing.org/t/selectfile-library-generates-a-fatal-exception-main-error/30175/13 "2021-08-09T18:26:46Z")

</div>

It has been updated since but here is the new processing code

```auto
import android.content.Intent;
BMS b;
fileInput f;
void setup() {
  size(600,600,P2D);
  b = new BMS(this);
  f = new fileInput(this);
  //f.folder = true;
  //f.file = true;
  f.image = true;
};

void draw() {
  background(255);
  f.displayImage();
  f.readContents();
};

void mousePressed() {
  f.getItem();
};

//@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
  f.handleActivity(requestCode,resultCode,data);
};

```

you need to download the github filewriterv1.jar

> **[GitHub - paulgoux/fileWriter-Android: file writer reader for android](https://github.com/paulgoux/fileWriter-Android)**
>
> file writer reader for android. Contribute to paulgoux/fileWriter-Android development by creating an account on GitHub.

when using folder

the files get sent to their respective arraylists

```auto
public String[] listFiles(String s1) {
		String []s = null;
		String path = s1;
		println("Files", "Path: " + path);
		File directory = new File(path);
		File[] files = directory.listFiles();
		if (files!=null) {
			s = new String [files.length];
			println("Files", "Size: "+ files.length);
			for (int i = 0; i < files.length; i++)
			{
				s[i] = files[i].getName();
				Files.add(s[i]);
				filterAll(s[i]);

				println("Files", "FileName: " + files[i].getName());
			}
		}
		println("Images", images.size());
		println("text", textFiles.size());
		println("Audio", audioFiles.size());
		println("Other", otherFiles.size());
		return s;
	};

```

there is also a video files arrayList `videoFiles`, just forgot to print it out

when loading an image the image gets stored to `fileInput.img` or whatever your fileInput instance is called.

when loading a file it gets stored to `fileContent` which is a `String` object, note it is not a `String[]` array and `/n` is used to separate lines.

---

<div class="post-metadata">

**Author:** ![mmuylle](https://avatars.discourse-cdn.com/v4/letter/m/ea5d25/32.png) [@mmuylle](https://discourse.processing.org/u/mmuylle)\
**Post date:** [August 9, 2021, 6:43pm UTC](https://discourse.processing.org/t/selectfile-library-generates-a-fatal-exception-main-error/30175/14 "2021-08-09T18:43:30Z")

</div>

Thanks, I give it a try and let you know but it might be tomorrow.  
marc

---

<div class="post-metadata">

**Author:** ![mmuylle](https://avatars.discourse-cdn.com/v4/letter/m/ea5d25/32.png) [@mmuylle](https://discourse.processing.org/u/mmuylle)\
**Post date:** [August 28, 2021, 4:04pm UTC](https://discourse.processing.org/t/selectfile-library-generates-a-fatal-exception-main-error/30175/15 "2021-08-28T16:04:21Z")

</div>

Hi Paul, It is a bit embarrassing but I cannot get the code run. So here is what I did. I combined the two code parts in a new sketch and added the Permission class. Made sure to allow reading and writing to the external storage. Dragged the filewriterv1.jar into the sketch. Checked that the jar is in the Lib directory.  
The following errors were generated:

1. The name “Files” cannot be recognized
2. The function “FilterAll(String)” does not exist.
3. The name "textFiles"cannot be recognized.  
It is obvious that I am missing something.  
Can you please put me on the right path.  
marc

here the complete code of the sketch  
(I am only looking for txt files)

```auto
import android.content.Intent;

BMS b;
fileInput f;
void setup() {
  size(600, 600, P2D);
  b = new BMS(this);
  f = new fileInput(this);
  f.folder = true;
  f.file = true;
  //f.image = true;
};

void draw() {
  background(255);
  f.displayImage();
  f.readContents();
};

void mousePressed() {
  f.getItem();
};

//@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
  f.handleActivity(requestCode, resultCode, data);
};

public String[] listFiles(String s1) {
  String []s = null;
  String path = s1;
  println("Files", "Path: " + path);
  File directory = new File(path);
  File[] files = directory.listFiles();
  if (files!=null) {
    s = new String [files.length];
    println("Files", "Size: "+ files.length);
    for (int i = 0; i < files.length; i++)
    {
      s[i] = files[i].getName();
      Files.add(s[i]);
      filterAll(s[i]);

      println("Files", "FileName: " + files[i].getName());
    }
  }
  //println("Images", images.size());
  println("text", textFiles.size());
  //println("Audio", audioFiles.size());
  //println("Other", otherFiles.size());
  return s;
};

public class Permission {

  PApplet parent;
  String p;

  public Permission(PApplet pParent, String permissionName) {
    parent = pParent;
    p = permissionName;
    parent.requestPermission("android.permission."+permissionName, "onPermissionResult", this);
  };

  public void onPermissionResult(boolean granted) {
    if (!granted) {
      PApplet.println("User did not grant", p, "permission.", p, "is disabled.");
    }
  };
};

```

---

<div class="post-metadata">

**Author:** ![paulgoux](https://avatars.discourse-cdn.com/v4/letter/p/b9bd4f/32.png) [@paulgoux](https://discourse.processing.org/u/paulgoux)\
**Post date:** [August 28, 2021, 4:17pm UTC](https://discourse.processing.org/t/selectfile-library-generates-a-fatal-exception-main-error/30175/16 "2021-08-28T16:17:14Z")

</div>

The bms library already includes a listFiles method so adding one to your sketch might cause conflicts, I was only showing you what it contains so you know the names of the arraylists, also the bms already handles the file read write permissions you don’t need to add it to the sketch.

---

<div class="post-metadata">

**Author:** ![mmuylle](https://avatars.discourse-cdn.com/v4/letter/m/ea5d25/32.png) [@mmuylle](https://discourse.processing.org/u/mmuylle)\
**Post date:** [August 28, 2021, 4:49pm UTC](https://discourse.processing.org/t/selectfile-library-generates-a-fatal-exception-main-error/30175/17 "2021-08-28T16:49:11Z")

</div>

Thanks. Keeping only the first part of the sketch solves indeed the problems. When I run the sketch on the phone I can easily find the the txt file which is located on the SD external storage /games/data/test.txt but I cannot select the file (it is greyed).

on the sketch console the following message is generated  
Bms paths: /storage/emulated/0 /data/user/0/processing.test.test\_paul02/files /data/user/0/processing.test.test\_paul02/files/data  
WRITE\_EXTERNAL\_STORAGE

marc

---

<div class="post-metadata">

**Author:** ![paulgoux](https://avatars.discourse-cdn.com/v4/letter/p/b9bd4f/32.png) [@paulgoux](https://discourse.processing.org/u/paulgoux)\
**Post date:** [August 28, 2021, 4:53pm UTC](https://discourse.processing.org/t/selectfile-library-generates-a-fatal-exception-main-error/30175/18 "2021-08-28T16:53:11Z")

</div>

That’s because you also have folder set to true. You can only do one or the other, however if both are true it will first attempt to locate a folder. So pointing to a file won’t work.

---

<div class="post-metadata">

**Author:** ![mmuylle](https://avatars.discourse-cdn.com/v4/letter/m/ea5d25/32.png) [@mmuylle](https://discourse.processing.org/u/mmuylle)\
**Post date:** [August 28, 2021, 5:04pm UTC](https://discourse.processing.org/t/selectfile-library-generates-a-fatal-exception-main-error/30175/19 "2021-08-28T17:04:22Z")

</div>

I commented out the f.folder = true; so that only f.file = true but the problem remains (the file is still grey)

---

<div class="post-metadata">

**Author:** ![paulgoux](https://avatars.discourse-cdn.com/v4/letter/p/b9bd4f/32.png) [@paulgoux](https://discourse.processing.org/u/paulgoux)\
**Post date:** [August 28, 2021, 6:18pm UTC](https://discourse.processing.org/t/selectfile-library-generates-a-fatal-exception-main-error/30175/20 "2021-08-28T18:18:29Z")

</div>

We’re you prompted for permissions when you loaded the sketch. The permissions still require you to set the request in processing, via the sketch permissions menu in the processing file bar.

---

<div class="post-metadata">

**Author:** ![mmuylle](https://avatars.discourse-cdn.com/v4/letter/m/ea5d25/32.png) [@mmuylle](https://discourse.processing.org/u/mmuylle)\
**Post date:** [August 28, 2021, 6:20pm UTC](https://discourse.processing.org/t/selectfile-library-generates-a-fatal-exception-main-error/30175/21 "2021-08-28T18:20:14Z")

</div>

Which were done already from the beginning.

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