Develop Reference

How to create files to a specific folder in android application?

In my application, I want to create a text file in the cache folder and first what I do is create a folder in the cache directory.
File myDir = new File(getCacheDir(), "MySecretFolder");
myDir.mkdir();
Then I want to create a text file in that created folder using the following code that doesn't seem to make it there. Instead, the code below creates the text file in the "files" folder that is in the same directory as the "cache" folder.
FileOutputStream fOut = null;
try {
fOut = openFileOutput("secret.txt",MODE_PRIVATE);
} catch (FileNotFoundException e) {
e.printStackTrace();
}
String str = "data";
try {
fOut.write(str.getBytes());
} catch (IOException e) {
e.printStackTrace();
}
try {
fOut.close();
} catch (IOException e) {
e.printStackTrace();
}
SO my question is, how do I properly designate the "MySecretFolder" to make the text file in?
I have tried the following:
"/data/data/com.example.myandroid.cuecards/cache/MySecretFolder", but it crashes my entire app if I try that. How should I properly save the text file in the cache/MySecretFolder?

use getCacheDir(). It returns the absolute path to the application-specific cache directory on the filesystem. Then you can create your directory
File myDir = new File(getCacheDir(), "folder");
myDir.mkdir();
Please try this maybe helps you.
Ok, If you want to create the TextFile in Specific Folder then You can try to below code.
try {
String rootPath = Environment.getExternalStorageDirectory()
.getAbsolutePath() + "/MyFolder/";
File root = new File(rootPath);
if (!root.exists()) {
root.mkdirs();
}
File f = new File(rootPath + "mttext.txt");
if (f.exists()) {
f.delete();
}
f.createNewFile();
FileOutputStream out = new FileOutputStream(f);
out.flush();
out.close();
} catch (Exception e) {
e.printStackTrace();
}

Just change
fOut = openFileOutput("secret.txt",MODE_PRIVATE);
to
fOut = openFileOutput(myDir+"/secret.txt",MODE_PRIVATE);
This will make secret.txt under MySecretFolder

getPrivateDir will create a folder in your private area (Context.MODE_WORLD_WRITEABLE- use what suits you from Context.MODE_...)
public File getPrivateDir(String name)
{
return context.getDir(name, Context.MODE_WORLD_WRITEABLE);
}
openPrivateFileInput will create a file if it doesn't exist in your private folder in files directory and return a FileInputStream :
/data/data/your.packagename/files
Your application private folder is in
/data/data/your.packagename
public FileInputStream openPrivateFileInput(String name) throws FileNotFoundException
{
return context.openFileInput(name);
}
If you package name is uno.due.com your app private folder is:
/data/data/uno.due.com
All directories underneath are weather created by you or by android for you. When you create a file as above it will go under:
/data/data/uno.due.com/files

Simple and easy code to create folder, file and write/append into the file
try {
String path = Environment.getExternalStorageDirectory().getAbsolutePath() + "/newfoldername/"; // it will return root directory of internal storage
File root = new File(path);
if (!root.exists()) {
root.mkdirs(); // create folder if not exist
}
File file = new File(rootPath + "log.txt");
if (!file.exists()) {
file.createNewFile(); // create file if not exist
}
BufferedWriter buf = new BufferedWriter(new FileWriter(file, true));
buf.append("hi this will write in to file");
buf.newLine(); // pointer will be nextline
buf.close();
}
catch (Exception e) {
e.printStackTrace();
}
NOTE: It needs the Android External Storage Permission so add below line in AndroidManifest.xml
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"></uses-permission>

Why does my old file contents get overwritten?

i'm using the below code to save log data to a file.
However, every time a new call is made, the old content is gone.....
i can't figure out what the issue is however....
public void writeToFile(String fileName, String textToWrite) {
FileOutputStream fOut = null;
try {
File root = new File(Environment.getExternalStorageDirectory() , fileName);
if (! root.exists()){
root.createNewFile();
}
fOut = new FileOutputStream(root);
OutputStreamWriter myOutWriter = new OutputStreamWriter(fOut);
myOutWriter.append(textToWrite);
myOutWriter.flush();
myOutWriter.close();
}
catch (Exception e) {
new MailService().mailMessage(e.toString());
}
finally{
if(fOut != null){
try{
fOut.close();
}
catch(Exception ex){
}
}
}
}

You need to pass second parameter boolean true to FileOutputStream constructor which indicates the file will be opened in append mode rather than write mode.
FileOutputStream out=new FileOutputStream("myfile");
Everytime you execute the above code it will open the file in write mode so that the new content will overwrite the old content. However, the FileOutputStream constructor accepts a second argument which is a boolean indicating whether to open the file in append mode.
FileOutputStream out=new FileOutputStream("myfile",true);
The above code will open the file in append mode so that the new content will be appended to the end of old content.
To know more about FileOutputStream constructors see this.

Android: Can't find generated XML file

I am working on a method that writes an XML file to the device. I've allowed external storage in the manifest file, but I can't find the file at the location it should be.
Here is my code:
public static void write (){
Serializer serial = new Persister();
File sdcardFile = new File("/Prueba/file.xml");
Item respuestas = new Item();
try {
serial.write(respuestas, sdcardFile);
} catch (Exception e) {
// There is the possibility of error for a number of reasons. Handle this appropriately in your code
e.printStackTrace();
}
Log.i(TAG, "XML Written to File: " + sdcardFile.getAbsolutePath());
}
}

Sdcard File path problem. Here is an exaple that write string in file.xml file.
File myFile = new File("/sdcard/file.xml");
try {
File myFile = new File("/sdcard/file.xml");
myFile.createNewFile();
FileOutputStream fOut = new FileOutputStream(myFile);
OutputStreamWriter myOutWriter =
new OutputStreamWriter(fOut);
myOutWriter.append("encodedString");
myOutWriter.close();
fOut.close();
} catch (Exception e) {
}
You able to get External Storage name by this way,
String root = Environment.getExternalStorageDirectory().toString();

Folder created on android sd card, but file not created

I think I have looked at all of the relevant questions and I still can't get this to work.
Here is the code:
File sdCard = Environment.getExternalStorageDirectory();
File directory= new File (sdCard.getAbsolutePath() + appName);
directory.mkdirs();
File file = new File(directory,fileName);
The folder is created, but I get an error saying the file does not exist. appName is a string containing the name of the folder and that works correctly. fileName is a string containing the name of the file I want to include.
I have included the permission in the manifest.
What am I doing wrong?
Update:
The code tries to make a subdirectory and a file at the same time, which hidden because the code uses a named String rather than a String literal. Adding an intermediate step to create the subdirectory solved the problem.

If the directory is created, then you're on the right track. In your code you are not actually creating the file on the SD card. If you need to create the file, then do this:
File sdCard = Environment.getExternalStorageDirectory();
File file = new File(sdCard.getAbsolutePath() + appName + "/" + fileName);
directory.mkdirs();
file.createNewFile()
This is notional only. It would be much better to actually separate your fileName into a separate subfolder and the actual file and handle them separately.

Try this out:
In this I am creating a text file (.txt file) of a string.
public void createFileFromString(String text)
{
File logFile = new File("sdcard/xmlresponseiphone.txt");
if (!logFile.exists())
{
try
{
logFile.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(logFile, true));
buf.append(text);
buf.newLine();
buf.close();
}
catch (IOException e)
{
// TODO Auto-generated catch block
e.printStackTrace();
}
}
Test this, and see what are you missing :)

Try with something like this. In this case I'm saving an image!
For creating the directory:
File directory = new File(Environment.getExternalStorageDirectory()
+ File.separator + appName);
directory.mkdirs();
And for saving into it
public void save(Bitmap graph, Context context, String name, String time, boolean now) throws IOException {
ByteArrayOutputStream bytes = new ByteArrayOutputStream();
graph.compress(Bitmap.CompressFormat.PNG, 100, bytes);
// you can create a new file name "test.jpg" in sdcard folder.
String fileName = "";
if (now){
fileName = getDateTime()+"_00"+".png";
}
else {
fileName = time.replace(".txt", ".png");
}
File f = new File(Environment.getExternalStorageDirectory()
+ File.separator + "appName/" + fileName);
f.createNewFile(); // write the bytes in file
FileOutputStream fo = new FileOutputStream(f);
fo.write(bytes.toByteArray());
}
I think the trick is in File.separator!

How to create files hierarchy in Androids '/data/data/pkg/files' directory?

I try to create 'foo/bar.txt' in Android's /data/data/pkg/files directory.
It seems to be a contradiction in docs:
To write to a file, call Context.openFileOutput() with the name and path.
http://developer.android.com/guide/topics/data/data-storage.html#files
The name of the file to open; can not contain path separators.
http://developer.android.com/reference/android/content/Context.html#openFileOutput(java.lang.String,%20int)
And when I call
this.openFileOutput("foo/bar.txt", Context.MODE_PRIVATE);
exception is thrown:
java.lang.IllegalArgumentException: File foo/bar.txt contains a path separator
So how do I create file in subfolder?

It does appear you've come across a documentation issue. Things don't look any better if you dig into the source code for ApplicationContext.java. Inside of openFileOutput():
File f = makeFilename(getFilesDir(), name);
getFilesDir() always returns the directory "files". And makeFilename()?
private File makeFilename(File base, String name) {
if (name.indexOf(File.separatorChar) < 0) {
return new File(base, name);
}
throw new IllegalArgumentException(
"File " + name + " contains a path separator");
}
So by using openFileOutput() you won't be able to control the containing directory; it'll always end up in the "files" directory.
There is, however, nothing stopping you from creating files on your own in your package directory, using File and FileUtils. It just means you'll miss out on the conveniences that using openFileOutput() gives you (such as automatically setting permissions).

You can add files with path in private directory like that
String path = this.getApplicationContext().getFilesDir() + "/testDir/";
File file = new File(path);
file.mkdirs();
path += "testlab.txt";
OutputStream myOutput;
try {
myOutput = new BufferedOutputStream(new FileOutputStream(path,true));
write(myOutput, new String("TEST").getBytes());
myOutput.flush();
myOutput.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}

Use getFilesDir() to get a File at the root of your package's files/ directory.

To write to a file in a subfolder of internal storage you will need to create the file (and subfolder if not already there) first, then create the FileOutputStream object.
Here is the method I used
private void WriteToFileInSubfolder(Context context){
String data = "12345";
String subfolder = "sub";
String filename = "file.txt";
//Test if subfolder exists and if not create
File folder = new File(context.getFilesDir() + File.separator + subfolder);
if(!folder.exists()){
folder.mkdir();
}
File file = new File(context.getFilesDir() + File.separator
+ subfolder + File.separator + filename);
FileOutputStream outstream;
try{
if(!file.exists()){
file.createNewFile();
}
//commented line throws an exception if filename contains a path separator
//outstream = context.openFileOutput(filename, Context.MODE_PRIVATE);
outstream = new FileOutputStream(file);
outstream.write(data.getBytes());
outstream.close();
}catch(IOException e){
e.printStackTrace();
}
}

Assuming the original post sought how to both create a subdirectory in the files area and write a file in it, this might be new in the docs:
public abstract File getDir (String name, int mode)
Since: API Level 1
Retrieve, creating if needed, a new directory in which the application
can place its own custom data files. You can use the returned File
object to create and access files in this directory. Note that files
created through a File object will only be accessible by your own
application; you can only set the mode of the entire directory, not of
individual files.