Develop Reference

Unable to create file in Android app

I am making a android app in which i am going to use File handling but to do that first i need to create it but by using following code:
File logf = new File("log1.txt");
Boolean bb = logf.exists();
if(!bb)
try {
bb = logf.createNewFile();
} catch (IOException e) {
msg.setText("not able to create file.");
}
'msg' is the TextView object which i am using to display error, and when i run this app.. it goes into IOException e catch.. Please tell me if i am doing something wrong or what?.. besides i am using Android 2.2 for my app.

In app storage, please try this:
File file = new File(getFilesDir(), "file.txt");
Or if you want to append file name, try this:
File file = new File(getFilesDir() + File.separator + "file.txt");

you need to provide absolute path of file like below.
File file = new File(/data/packagename/files/ + "log1.txt");

Android: Create and Download PDF files to Downloads directory

In my Android App, in one of the activity, there is a "PDF Download" button. When this button is clicked, I create a PDF and then download it to the "Downloads" directory. Following is my code which runs on the click event of the button:
public void createAndDownloadPDF()
{
try
{
PdfDocument document = new PdfDocument();
View content = this.findViewById(android.R.id.content);
PdfDocument.PageInfo pageInfo = new PdfDocument.PageInfo.Builder(content.getWidth(),
content.getHeight() - 20, 1).create();
PdfDocument.Page page = document.startPage(pageInfo);
content.draw(page.getCanvas());
document.finishPage(page);
SimpleDateFormat sdf = new SimpleDateFormat("ddMMyyyyhhmmss");
String pdfName = "pdfdemo"
+ sdf.format(Calendar.getInstance().getTime()) + ".pdf";
File outputFile = new File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS), pdfName);
try
{
outputFile.createNewFile();
OutputStream out = new FileOutputStream(outputFile);
document.writeTo(out);
document.close();
out.close();
}
catch (IOException e)
{
e.printStackTrace();
}
}
catch(Exception e)
{
Toast.makeText(getApplicationContext(), e.getMessage(), Toast.LENGTH_LONG).show();
}
}
Please note that I added the required WRITE permission to the MANIFEST file and also asking for the permission at runtime. So, there is no issue of permissions.
When I debug the code, I notice that "outputFile" variable holds this path:
/storage/emulated/o/Download/pdfdemo07052017121233.pdf
My users will never find above path in their mobile. So, they will have no clue where their PDF got saved. I want that when users click on "Downloads" icon on their mobile, they should see the PDF file they downloaded from the app.
So, I think if I can sort out the following line:
File outputFile = new File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS), pdfName);
my work will be done. What should be the path I use so that my PDF files get saved / downloaded in the "Downloads" directory? I researched over the internet, but did not find any concrete solution.

Try this:
File outDir = new File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS).toString());
If this doesn't work, evaluate the chance of having your PDF file previously generated and saved into a folder inside your Assets folder. If this can be the case, after the above line you insert this:
copyAssets("XXX",outDir.toString());
Where "XXX" is the name of the folder inside your Assets folder which will contain the PDF file. This will copy the contents of XXX to DOWNLOADS/XXX on your device.

Creating a file unsing openFileOutput() which is visible to other applications

I'm using the openFileOutput() to create a new txt file. I need the file to be visible from other applications (as well as from a PC when the Android device is connected via USB. Ive tried using .setReadable(true); but this does not seem valid. Please advise how I should declare the file is visible / public.
try {
textIncoming.append("saving");
final String STORETEXT = "test.txt";
OutputStreamWriter out = new OutputStreamWriter(openFileOutput(STORETEXT, 0));
out.setReadable(true);
out.write("testing");
out.close();
}
catch (Throwable t) {
textIncoming.append("not saving");
}
Ive changed my program to use getExternalStoragePublicDirectory(Environment.DIRECTORY_DOCUMENTS), but for some reason it returns a path /storage/emulated/0/Documents, and I cant even find this folder on the device. Ive looked at the files on the android device using ES file explorer but cant find the folder or file I'm trying to create (Plus I want these in an documents folder on the SD card, so it seems that its not giving me a pointer to the SD card at all, and not creating the folder, and not creating the file. Following is my updated code, please advise
String root = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOCUMENTS).toString();
File myDir = new File(root + "/Saved_Receipts");
myDir.mkdirs();
Random generator = new Random();
int n = 10000;
n = generator.nextInt(n);
String fname = "DRcpt-" + n + ".xml";
textIncoming.append(root);
File file = new File(myDir, fname);
if (file.exists()) {
file.delete();
}
try {
FileOutputStream out = new FileOutputStream(file);
out.flush();
out.close();
}
catch (Exception e) {
e.printStackTrace();
}

Save it to sdcard if you want anyone to be able to read it.
This android documentation should tell you what you need to do.
https://developer.android.com/guide/topics/data/data-storage.html#filesExternal

openFileOutput() documentation says:
Open a private file
So the file that it creates won't be visible to other apps, unless you copy it to another directory that is visible. In that case, you have to save your data in what's called "external storage" which is shared with other apps. Use the code at this link.

[Android ]Intent.ACTION_VIEW - Not found

I am having an issue, I have never had problem opening files via ACTION_VIEW the next way:
File file = new File(getActivity().getFilesDir(), TEMP_FILE_NAME);
String dataType = "image/*";
if (file.exists()) {
Intent fileIntent = new Intent(Intent.ACTION_VIEW);
fileIntent.setDataAndType(Uri.fromFile(file), dataType);
fileIntent.setFlags(Intent.FLAG_ACTIVITY_NO_HISTORY);
Intent intent = Intent.createChooser(fileIntent, "Open file");
try {
startActivity(intent);
} catch (ActivityNotFoundException e) {
e.printStackTrace();
Log.e(TAG, "There is a problem when opening the file");
}
} else {
Toast.makeText(getContext(), "Invalido", Toast.LENGTH_LONG).show();
}
The problem I am having right now is that even though the file exists when I choose the app to open the file it immediately closes and tells me Not found. I have put the image I am loading in an image view and there is no problem, so the file is valid but for some reason it has conflicts when I am opening it via intent.
I am aware that it may have something to do with the way I am creating the file, I am retrieving it from Google drive so I am writing the file using the Apache Commons library the next way:
DriveContents contents = result.getDriveContents();
InputStream inputStream = contents.getInputStream();
File file = new File(getActivity().getFilesDir(), TEMP_FILE_NAME);
try {
OutputStream outputStream = new FileOutputStream(file);
IOUtils.copy(inputStream, outputStream);
IOUtils.closeQuietly(inputStream);
IOUtils.closeQuietly(outputStream);
} catch (IOException e) {
e.printStackTrace();
}
What is it I am doing wrong? I am not totally sure if the problem has to do with the copy method executing asynchronously or something like that.
Thanks in advance.

I have never had problem opening files via ACTION_VIEW the next way
That code will never work, as third-party apps have no rights to work with files on getFilesDir() of your app.
What is it I am doing wrong?
You are attempting to serve an inaccessible file to third-party programs. Use FileProvider to serve the file, using FileProvider.getUriForFile() to get the Uri to use in your ACTION_VIEW Intent.

Android: Cannot see file saved on external storage

public void write(View view)
{
String state;
File Dir = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS);
if (!Dir.exists())
{
Dir.mkdir();
}
File file = new File(Dir,"nahk.txt");
Toast.makeText(getApplicationContext(),file.getAbsolutePath(), Toast.LENGTH_SHORT).show();
String Message = "5nahk";
try {
FileOutputStream FOS = new FileOutputStream(file);
FOS.write(Message.getBytes());
FOS.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
I have added write permission in the manifest xml file. This method is called when I press a button. The toast says that the txt file is saved in the Download folder of my Internal Storage (since I don't have an SD card in my LG G3). I open the file location (using FileManager on my LG G3) and there is no "nahk.txt" in that folder. Why can't I see the file?

I'm not familiar with native android development but I encountered something similar using cordova. After saving a file the file was not visible browsing with a usb cable but it was actually there. To see it had to restart my device.
So you could try to restart your device and check if it is still invisible (or create a method which fetches or checks the existence of the saved file to check if it is there).
edit: I learned this by googling so you should find it also

Try this
File Dir = Environment.getExternalStorageDirectory().getAbsolutePath() + "/Your_Folder_Name";
File file = new File(Dir,"nahk.txt");
this file will save inside of your device storage Your_Folder_Name