Develop Reference

Create CSV or TXT file in app and save it to 'download' folder - Android

I searched and tried a lot before asking this.
But all the code that I'm trying is not working.
I want the file to be stored in the download folder and be accessible from the user also if he uninstalls the app.
I also tried using opencsv library. Could you provide a tested way to create a csv or txt file and store to download folder?

Save to to publicDir(Downloads folder) you first need permission.WRITE_EXTERNAL_STORAGE
check docs
Note this won't work without permmissions
private void saveData(){
String csv_data = "";/// your csv data as string;
File root = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS);
//if you want to create a sub-dir
root = new File(root, "SubDir");
root.mkdir();
// select the name for your file
root = new File(root , "my_csv.csv");
try {
FileOutputStream fout = new FileOutputStream(root);
fout.write(csv_data.getBytes());
fout.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
boolean bool = false;
try {
// try to create the file
bool = root.createNewFile();
} catch (IOException ex) {
ex.printStackTrace();
}
if (bool){
// call the method again
saveData()
}else {
throw new IllegalStateException("Failed to create image file");
}
} catch (IOException e) {
e.printStackTrace();
}
}

Write user readable file

I am writing values to my database and stop the time it needs for an evaluation.
Now I would like to write these times to an easy accessible file like a .txt but I can not write on the phone (some answers on the internet say because it is connected as "media source" but when I disconnect it I can not connect to eclipse anymore).
So the question is: How can I write a file which I can simply copy from my phone to my PC to get the data to analyze them.

you can use below function, text is your content:
public void backUp(String text,String namefile)
{
File file = new File(Environment.getExternalStorageDirectory()+"/yourdir/"+namefile+".txt");
if (!file.exists())
{
try
{
file.createNewFile();
}
catch (IOException e)
{
// TODO Auto-generated catch block
e.printStackTrace();
}
}
try
{
//BufferedWriter for performance, true to set append to file flag
BufferedWriter buf = new BufferedWriter(new FileWriter(file, true));
buf.append(text);
buf.newLine();
buf.close();
}
catch (IOException e)
{
// TODO Auto-generated catch block
e.printStackTrace();
}
}
updated :
you should create your directory before use above function :
File yourdir = new File(Environment.getExternalStorageDirectory()+"/yourdir");
if(!yourdir.exists()){
yourdir.mkdir();
}
then :
backUp("hello world", "test");
don't forget this permission :
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>

file has been created but when opened nothing is in it

I have an android app and simply i need to store data in a file. I need to use external storage to make it available for other applications too.
im using this piece of code
BufferedWriter bw;
try {
bw = new BufferedWriter(new FileWriter("/storage/sdcard0/download/themagicfile.txt", true));
bw.write("hi");
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
which i got from http://stackoverflow.com/questions/10041007/write-to-txt-file-but-not-overwrite
I can see the file in the directory but when i open it there is nothing in it. i need to use FileWriter to make it appendable.
any suggestion

you should also call
bw.flush();
bw.close();
rembember to add the WRITE_EXTERNAL_STORAGE permission to the AndroidManifest.xml file
try {
bw = new BufferedWriter(new FileWriter("/storage/sdcard0/download/themagicfile.txt", true));
bw.write("hi");
bw.flush();
} (IOException e) {
e.printStackTrace();
} finally {
try {
bw.close();
} (IOException e) { }
}

android EROFS in eclipse

I am trying to read some files and put them into a new file using the below method in Eclipse.
But I am getting a read-only file system EROFS error in eclipse at run time.
Input file names will be provided as function parameter. Files are present in res\raw folder.
SampleFile.mp3 is an empty audio file placed at the location.
public void myfun(Set s)
{
try {
FileOutputStream fos=new FileOutputStream(".\\res\raw\sampleFile.mp3",true);
FileInputStream fis;
Iterator ptr=s.iterator();
String str;
while(ptr.hasNext()!=null)
{
str=ptr.next().toString();
fis=new FileInputStream(str);
int i;
while((i=fis.read())!=-1)
{
fos.write(i);
}
fis.close();
}
fos.flush();
fos.close();
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}

You are trying to write into the 'res/raw' folder of the current directory, but android does not work like that. Go read the Storage Options section of the Android Development Guide, and choose one that fits your needs (and use case).
Also, you want to concatenate multiple files into an mp3? Are they by any chance... mp3 files themselves that you want to play?

Android filewrite nullpointer exception

In my app there are 3 EditTexts. I want to write the content of this EditTexts to a file, but the filewrite throws a nullpointer exception. Why?
OutputStream f1; is declared globally.
BtnSave = (Button)findViewById(R.id.Button01);
BtnSave.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
intoarray = name + "|" + number + "|" + freq + "\n";
Toast.makeText(Main.this, "" + intoarray, Toast.LENGTH_SHORT).show();
//so far so good
byte buf[] = intoarray.getBytes();
try {
f1 = new FileOutputStream("file2.txt");
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
try {
f1.write(buf); //nullpointer exception
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
try {
f1.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}

Most likely
f1 = new FileOutputStream("file2.txt");
failed and since you caught the exception f1 remained null. In most cases in Android you can only create files either in your application data directory or external storage.

The way you are currently using this won't work, generally you are trying to write to internal storage, which is private to your app and must be contained within your applications directory.
The proper way to create the file stream is
fin = openFileOutput("file2.txt", Context.MODE_PRIVATE); // open for writing
fout = openFileInput("file2.txt", Context.MODE_PRIVATE); // open for reading
Which will locate the file in your storage area for your application, which is typically something like
/data/data/com.yourpackagename/files/...
You can still create directories within your applications area if you need a directory structure of course.
If you need to write to external storage that's a different process, for more information see Android Data Storage

Sorry for all you were trying help me, I asked the wrong question. I wanted to use internal storage (and it is now working). I don't know what the problem is, but the with the code below (that i have used a lot) filewrite is ok:
try {
File root = Environment.getExternalStorageDirectory();
File file = new File(root, "Data.txt");
if (root.canWrite()) {
FileWriter filewriter = new FileWriter(file, true);
BufferedWriter out = new BufferedWriterfilewriter);
out.write(intoarray);
out.close();
}
} catch (IOException e) {
Log.e("TAG", "Could not write file " + e.getMessage());
}
I would delete the topic if I could. I accept this answer to close the topic.
Thanks, anyway.