Develop Reference

Writing file in Android always fails

I want to write text to file in Android. I tried writing to sdcard and public part of internal storage. I always got FileNotFound exception. I tried to get path by Environment.getExternalStorageDirectory().getAbsolutePath() and by Environment.getExternalStoragePublicDirectory(Enviroment.DIRECTORY_DCIM).getAbsolutePath()(it does not metter the file is not a picture, I suppose) and both returned: "storage/emulated/0" and "storage/emulated/0/DCMI" respectively. I have also tried direct path "/sdcard/MyFile/output.txt" and "mnt/sdcard/MyFile/output.txt". I have checked on most stackoverflow.com answears in such topic but I got only code similar to mine. (like from here)
Example of my code (I tried more variations):
try {
File dir = Environment.getExternalStorageDirectory();
File dir = new File (sdCard.getAbsolutePath() + "/MyFile");
if (!dir.exists()) {
dir.mkdirs();
}
File file = new File(dir, "output.txt");
if (!file.exists()) {
file.createNewFile();
}
FileOutputStream stream = new FileOutputStream(file);
stream.write(("some text").getBytes());
stream.close();
toast = Toast.makeText(context, "Saving file successful.", Toast.LENGTH_SHORT);
toast.show();
} catch (Exception e) {
toast = Toast.makeText(context, Environment.getExternalStorageDirectory().getAbsolutePath(), Toast.LENGTH_SHORT);
//toast = Toast.makeText(context, e.toString(), Toast.LENGTH_SHORT);
toast.show();
}

You have to set the
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
permission in your AndroidManifest.xml file.
If you run your app on Android 6.0 or higher you have to request this permission at runtime.
Request App Permissions

I am sorry to all you guys to waste your time. The problem was in permission setting. Here is the answear.

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

writing to a file in android, couldn't locate file

so i have this code below in my MainActivity, after I call this method, it pop up Toast "file saved" but i could not locate this file to be sure it saves what i wanted to, anyone?
private void saveToFile(String data){
try {
outFile = new FileWriter(Environment.getExternalStorageDirectory().getAbsolutePath()+"/batteryLogFile.txt", true);
PrintWriter out = new PrintWriter(outFile);
out.println(data);
out.close();
//output = new FileOutputStream(Environment.getExternalStorageDirectory().getAbsolutePath()+"/batteryLogFile.txt");
//output.write(data.getBytes());
//output.close();
Toast.makeText(getBaseContext(), "file saved", Toast.LENGTH_SHORT).show();
}catch(FileNotFoundException e){
Toast.makeText(getBaseContext(), e.getMessage(), Toast.LENGTH_SHORT).show();
}catch(java.io.IOException e){
Toast.makeText(getBaseContext(), e.getMessage(), Toast.LENGTH_SHORT).show();
}
}

I've finally found the file, issue was about that I was debugging this app on my real device and while it was debugging, somehow app hasn't been saving my file. When I disconnect my device from computer and re-run application again, everything was good and file was located on my SD card.

checking if a directory is created or not, fails?

I'm trying to create a directory, and i'm checking whether it is created successfully or not but displaying a text on the screen, but nothing to be displayed.
Java code:
public void createDirectory() {
try {
String strDirectory = "test";
boolean success = ( new File(strDirectory)).mkdir();
if (success) {
Toast.makeText(getBaseContext(), "Directory "+strDirectory+" created", Toast.LENGTH_SHORT);
} else {
Toast.makeText(getApplicationContext(), "error occured", Toast.LENGTH_SHORT);
}
} catch (Exception e) {
Log.e("Error", "Error creating directory");
}
}

put .show() end of Both Toast....
Toast.makeText(getBaseContext(), "Directory "+strDirectory+" created",
Toast.LENGTH_SHORT).show();

Did you add uses-permission write external storage to your manifest?
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
I actually don't know where it's trying to create the directory since you are not qualifying the entire path. what are you trying to do?
If you are trying to create it on the SD card, do this,
File f = new File(Environment.getExternalStorageDirectory(), "myfile.txt");
http://developer.android.com/reference/android/os/Environment.html
Note that this file will be readable by all apps.
If you are trying to create a file that's private to the app, do this,
OutputStream os = context.openFileOutput("myfile.txt");
http://developer.android.com/reference/android/content/Context.html
Note that this method is reserved for small files as it uses the internal storage which is limited on many devices.
Finally, always print the stack trace,
Log.e("mytag", "some message", e);
9 times out of ten, this will point you directly to the problem.

Can I access the files I create with USB

I'm lost here.
I create files using this (stripped) code :
File dir = getBaseContext().getDir(dirPath, MODE_WORLD_WRITEABLE);
try {
File file = new File(dir, fileName);
FileOutputStream fous = new FileOutputStream(file);
fous.write(data);
fous.flush();
fous.close();
long l = file.length();
Log.i("PpCameraActivity", "File size : " + l);
} catch (IOException e) {
e.printStackTrace();
Toast.makeText(getBaseContext(), "Error while trying to write photo file", Toast.LENGTH_LONG).show();
}
I can verify with logcat that my file seems to be created (it has a not null lenght). But I cannot see it when I connect my android device to my PC.
So... where is my file ? Is it hidden ? Erased ?
EDIT : I'm now trying to write on the SDCard specifically, using this :
File root = Environment.getExternalStorageDirectory();
File jpegFile = new File(root.getAbsolutePath() + "/myApplication/" + filePath);
try {
jpegFile.mkdirs();
FileOutputStream fous = new FileOutputStream(jpegFile);
fous.write(data);
fous.flush();
fous.close();
Log.i("PpCameraActivity", "File written : " + jpegFile.getAbsolutePath());
Toast.makeText(getBaseContext(), "File written : " + jpegFile.getAbsolutePath(), Toast.LENGTH_LONG).show();
long l = jpegFile.length();
Log.i("PpCameraActivity", "File size : " + l);
} catch (IOException e) {
e.printStackTrace();
Toast.makeText(getBaseContext(), "Error while trying to write photo file", Toast.LENGTH_LONG).show();
}
But I get a FileNotFoundException on the FileOutputStream creation...

OK found it.
Not an Android problem but just my error (not the first time) : mkdirs must be applied to the parent file, not the file I want to write...
So, for people interested :
Access the sd card using
File root = Environment.getExternalStorageDirectory();
Don't forget to require this permission
WRITE_EXTERNAL_STORAGE
Then make, as usual, mkdirs and file creation.
And don't forget : the android device cannot write on the sdard while it is mounted on you PC.

You probably aren't writing to the SD card, and the SD contents are all you can see from a USB connection.
Try something like this: http://androidgps.blogspot.com/2008/09/writing-to-sd-card-in-android.html (just the first thing that came up when I searched for "Android write to SD card").