Develop Reference

How to create a shared folder usable by my android app?

I've got a question that probably borders on opinion, but I've not any related questions or documentation that answers, so I feel like it's a fair one to ask.
I'm trying to build an android app which modifies music files, and what I'd like to do is have a shared folder so that the files and the results can be accessible and shared. I'd like it if it was among the other folders like Music, Downloads, Movies, etc, or even under Music since it's music related. However this seems like it's a security no no in Android, as after I've made something and put it in there I have to use an intent to access it again, where as I'd rather just be able to open the files and not have a permissions based fiasco. Maybe some type of symbolic link like in Linux that pointed to my apps internal folder could be used, but of this I'm still uncertain.
In any case, is there a way I should go about this? If so, are there some resources I could be pointed to?
Thank you in advance to anyone who takes this up!
Edit for CommonsWare:
I used the following to create the folder:
File mediaStorageDir = new File(Environment.getExternalStorageDirectory(), APP_NAME);
And this to copy files from elsewhere to there:
public void copyFileToHomeDirectory(Uri uri)
{
try
{
ContentResolver contentResolver = getApplicationContext().getContentResolver();
String fileName = queryName(contentResolver, uri);
//Get file extension
String fileType = fileName.substring(fileName.length() - 4, fileName.length());
if(fileType.equalsIgnoreCase(MP3_EXTENSION))
{
String path = Environment.getExternalStorageDirectory() + APP_FOLDER;
InputStream in = contentResolver.openInputStream(uri);
File outputFile = new File(path + File.separator + fileName);
outputFile.createNewFile();
OutputStream out = new FileOutputStream(outputFile);
//First we crack open the file to copy it's contents:
byte[] buffer = new byte[KB_SIZE];
int read;
while ((read = in.read(buffer)) != -1)
{
out.write(buffer, 0, read);
}
in.close();
in = null;
// write the output file (You have now copied the file)
out.flush();
out.close();
out = null;
}
}
catch(FileNotFoundException fnfe)
{
Log.e(TAG, "FileNotFoundException");
Log.e(TAG, Log.getStackTraceString(fnfe));
}
catch(IOException ioe)
{
Log.e(TAG, "IOException");
Log.e(TAG, Log.getStackTraceString(ioe));
}
catch(Exception e)
{
Log.e(TAG, "General Exception");
Log.e(TAG, Log.getStackTraceString(e));
}
}
I've tried other methods that I've overwritten in the process, but accessing the files to be used again I need something like this:
public void openDirectory(View view)
{
// Choose a directory using the system's file picker.
Intent intent = new Intent(Intent.ACTION_GET_CONTENT);
// Provide read access to files and sub-directories in the user-selected
// directory.
//intent.addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);
//intent.putExtra(Intent.EXTRA_ALLOW_MULTIPLE, true);
//intent.addCategory(Intent.CATEGORY_OPENABLE);
// Optionally, specify a URI for the directory that should be opened in
// the system file picker when it loads.
//intent.putExtra(DocumentsContract.EXTRA_INITIAL_URI, uriToLoad);
intent.putExtra(Intent.EXTRA_ALLOW_MULTIPLE, true);
intent.addCategory(Intent.CATEGORY_OPENABLE);
intent.setType("*/*"); //use image/* for photos, etc.
//The result of this code will be calling the onActivityResult function below
startActivityForResult(intent, REQUEST_MUSIC_DIR);
}
Edit2:
I've reorganized the folders to what I think I should be doing so that I can work with the files freely, however, even in my internal cache storage (getCacheDir() + folder_name) either isn't letting me create the files (outputFile.createNewFile doesn't throw an error) or it isn't letting me open them when I go to get a directory listing.
Here's my code for creating the file:
String path = getCacheDir() + MY_SUB_FOLDER;
//uri is obtained through ACTION_OPEN_DOCUMENT intent
InputStream in = contentResolver.openInputStream(uri);
File outputFile = new File(path + "/" + fileName);
outputFile.createNewFile();
Log.i(TAG, "The new file's directory/path is: " + outputFile.getAbsolutePath());
//NOTE: This is returning /data/user/0/com.example.myapplication/cache/MY_SUB_FOLDER/file_name.mp3
OutputStream out = new FileOutputStream(outputFile);
byte[] buffer = new byte[1024];
int read;
while ((read = in.read(buffer)) != -1)
{
out.write(buffer, 0, read);
}
in.close();
in = null;
out.flush();
out.close();
out = null;
This is my code for attempting to open and read these newly created files
File directory = new File(getCacheDir(), MY_SUB_FOLDER);
Log.i(TAG, "This is the directory we're trying to get the files from: " + directory.getAbsolutePath());
//NOTE: This returns /data/user/0/com.example.myapplication/cache/MY_SUB_FOLDER
File[] files = directory.listFiles();
if(files != null)
{
for(int i = 0; i < files.length; i++)
{
Log.d(TAG, "Files found: " + files[i].getAbsolutePath());
}
}
The files variable isn't null but it's length is 0 and no files are found.
Edit3:
I am catching the exceptions and logging any stack traces, which currently returns nothing.
catch(FileNotFoundException fnfe)
{
Log.i(TAG, "FileNotFoundException");
Log.i(TAG, Log.getStackTraceString(fnfe));
}
catch(IOException ioe)
{
Log.i(TAG, "IOException");
Log.i(TAG, Log.getStackTraceString(ioe));
}
catch(Exception e)
{
Log.i(TAG, "General Exception");
Log.i(TAG, Log.getStackTraceString(e));
}

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>

Android create a text file on internal storage, email it, then delete the file

I want to be able to create a text file with data inside of it, email that file, and then get rid of it on my Android device.
Below is what I have so far but it is giving me the error:
java.io.FileNotFoundException: /20150719_130219: open failed: EROFS (Read-only file system)
Code:
BufferedWriter writer = null;
try {
//create a temporary file
String report = new SimpleDateFormat("yyyyMMdd_HHmmss").format(Calendar.getInstance().getTime());
File logFile = new File(report);
writer = new BufferedWriter(new FileWriter(logFile));
for (Map.Entry entry : cbh.data.entrySet()) {
reportText.append(entry.getKey() + ", " + entry.getValue() + "\n");
writer.write(entry.getKey() + ", " + entry.getValue() + "\n");
}
} catch (Exception e) {
e.printStackTrace();
} finally {
try {
writer.close();
} catch (Exception e) {
}
}

First you need to provide permissions in your manifest file
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
Second in your code you are just generating the name of the file but its complete path is not defined where it will be saved.
Environment.getExternalStorageDirectory()
will return the path of sdcard
You can write this
String report = new SimpleDateFormat("yyyyMMdd_HHmmss").format(Calendar.getInstance().getTime());
String fileName = Environment.getExternalStorageDirectory()+ report+".txt";
File file = new File(fileName);

Android unzip open failed: ENOENT (No such file or directory)

I am using the following code to unzip a set of files (containing folders as well):
private boolean unpackZip(String path, String zipname)
{
InputStream is;
ZipInputStream zis;
try
{
String filename;
is = new FileInputStream(path + zipname);
zis = new ZipInputStream(new BufferedInputStream(is));
ZipEntry ze;
byte[] buffer = new byte[1024];
int count;
while ((ze = zis.getNextEntry()) != null)
{
// zapis do souboru
filename = ze.getName();
// Need to create directories if not exists, or
// it will generate an Exception...
if (ze.isDirectory()) {
File fmd = new File(path + filename);
fmd.mkdirs();
continue;
}
FileOutputStream fout = new FileOutputStream(path + filename);
// cteni zipu a zapis
while ((count = zis.read(buffer)) != -1)
{
fout.write(buffer, 0, count);
}
fout.close();
zis.closeEntry();
}
zis.close();
}
catch(IOException e)
{
e.printStackTrace();
return false;
}
return true;
}
The code fails on FileOutputStream fout = new FileOutputStream(path + filename) with the error:
java.io.FileNotFoundException: /storage/emulated/0/BASEFOLDER/FOLDER1/FILE.png
BASEFOLDER already exists, that is where I am trying to unzip the folder to. If I manually (or programmatically) create FOLDER1, the code runs fine and successfully unzips. I believe it is crashing because the very first file (ze) is named FOLDER1/FILE.png and FOLDER1 hasn't been created yet. How do I get around this? I know other people have used this code, I find it unlikely that it randomly doesn't work for me...

Have you got this in your AndroidManifest.xml file?
Add Write to external Storage permission
uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"

I had the same problem. After several investigation I found that. put following single line in your code:
if (ze.isDirectory()) {
File fmd = new File(path + filename);
fmd.mkdirs();
zis.closeEntry(); // <<<<<< ADD THIS LINE
continue;
}

Sometime the extract files has been extracted before its parent directory is created, for example:
File A inside directory B. But B directory is not created, index of files listing below cause the issue:
dir_b/file_a.txt
dir_b/
dir_b/file_c.txt
So, to sure directory created before file extracting, you need to create parent directories first, for example:
val targetFile = File(tempOutputDir, zipEntry.name)
if (zipEntry.isDirectory) {
targetFile.mkdirs()
} else {
try {
try {
targetFile.parentFile?.mkdirs() // <-- ADD THIS LINE
} catch (exception: Exception) {
Log.e("ExampleApp", exception.localizedMessage, exception)
}
val bufferOutputStream = BufferedOutputStream(
FileOutputStream(targetFile)
)
val buffer = ByteArray(1024)
var read = zipInputStream.read(buffer)
while (read != -1) {
bufferOutputStream.write(buffer, 0, read)
read = zipInputStream.read(buffer)
}
bufferOutputStream.close()
} catch (exception: Exception) {
Log.e("ExampleApp", exception.localizedMessage, exception)
}
}

Android: How to create a directory on the SD Card and copy files from /res/raw to it?

I am trying to create a folder and several subdirectory within it on the SD Card... I then want to transfer files that I have stored in /res/raw to that folder... I addition, I want this to only happen once, the first time the program is ever run. I realize that this is ridiculously open-ended, and that I am asking a lot... but any help would be greatly appreciated.

This will copy all files in the "clipart" subfolder of the .apk assets folder to the "clipart" subfolder of your app's folder on the SD card:
String extStorageDirectory = Environment.getExternalStorageDirectory().toString();
String basepath = extStorageDirectory + "/name of your app folder on the SD card";
//...
// in onCreate
File clipartdir = new File(basepath + "/clipart/");
if (!clipartdir.exists()) {
clipartdir.mkdirs();
copyClipart();
}
private void copyClipart() {
AssetManager assetManager = getResources().getAssets();
String[] files = null;
try {
files = assetManager.list("clipart");
} catch (Exception e) {
Log.e("read clipart ERROR", e.toString());
e.printStackTrace();
}
for(int i=0; i<files.length; i++) {
InputStream in = null;
OutputStream out = null;
try {
in = assetManager.open("clipart/" + files[i]);
out = new FileOutputStream(basepath + "/clipart/" + files[i]);
copyFile(in, out);
in.close();
in = null;
out.flush();
out.close();
out = null;
} catch(Exception e) {
Log.e("copy clipart ERROR", e.toString());
e.printStackTrace();
}
}
}
private void copyFile(InputStream in, OutputStream out) throws IOException {
byte[] buffer = new byte[1024];
int read;
while((read = in.read(buffer)) != -1){
out.write(buffer, 0, read);
}
}

I experienced a similar problem when using mkdirs(), however because running the command:
mkdir one/two
fails on Linux, then the method http://download.oracle.com/javase/1.4.2/docs/api/java/io/File.html#mkdirs() subsequently fails too. I guess this means there is no way to use mkdirs on Android? My (probably rather hacky) work-around was to create each necessary directory separately:
String extStorageDirectory = Environment.getExternalStorageDirectory().toString();
new File(extStorageDirectory + "/one/").mkdirs();
new File(extStorageDirectory + "/one/two/).mkdirs();