Develop Reference

Android, how to choose save file location?

is there any solution how to choose the saving files location?
maybe with the original file browser, to choose the destination?
thank you!

All you need is Android Directory Picker

Better to save files with your app namespace:
String extStorage = Environment.getExternalStorageState();
path = extStorage+"/Android/data/com.mydomain.myapp/";
It will be deleted when app gets uninstalled.
Here is actually everything about data storing.
http://developer.android.com/guide/topics/data/data-storage.html
From the above link:
If you're using API Level 7 or lower, use
getExternalStorageDirectory(), to open a File representing the
root of the external storage. You should then write your data in the
following directory:
/Android/data/<package_name>/files/

It's probably easiest and expected to save this out to the dedicated area on the external SD card.
You can get this folder by calling
file://localhost/Applications/android-sdk-macosx/docs/reference/android/os/Environment.html#getExternalStoragePublicDirectory(java.lang.String)
File path = Environment.getExternalStoragePublicDirectory(
Environment.DIRECTORY_PICTURES)
You can also append a sub-folder to reference the source better ie. your app.
You can either choose DIRECTORY_PICTURES or DIRECTORY_MOVIES. If it's user created I'd probably stick to pictures.
To be helpful you can also call the media scanner to add it to the appropriate content provider system wide.
sendBroadcast( new Intent(Intent.ACTION_MEDIA_MOUNTED,
Uri.parse("file://" + Environment.getExternalStorageDirectory()))
);
If you MUST get a file chooser going, which isn't the recomened approach to expose the user to the file system. Try the file chooser form Open Intents. http://www.openintents.org/en/node/164

How to create private folder in sdcard

My application is used for security purpose. so, from my application user captures photos that all photos are stored in a folder that folder should not access from any other application and should not give access when devices connect to computer system. If user wants to view these images he should access only from my application.

According to this guide, you can save files directly on the device's internal storage. By default, files saved to the internal storage are private to your application and other applications cannot access them (nor can the user). When the user uninstalls your application, these files are removed.
For example:
String FILENAME = "hello_file";
String string = "hello world!";
FileOutputStream fos = openFileOutput(FILENAME, Context.MODE_PRIVATE);
fos.write(string.getBytes());
fos.close();
MODE_PRIVATE will create the file (or replace a file of the same name) and make it private to your application. Other modes available are: MODE_APPEND, MODE_WORLD_READABLE, and MODE_WORLD_WRITEABLE.

The only way, AFAIK is to encrypt the files that you store. There is no way to prevent users mount the sdcard to access every file stored in it.

according to this related question, you can only create protected files in internal storage (not on the SD)...
Create Folder that can not accessible by any other application

Try following solution:
How to store a file in Hidden mode
Although it is not exactly what you want and I doubt whether it is possible or not. The best option would be to make it hidden but that also works with constraint (works for linux and not for Windows, still other applications can access the folder)
How to hide the folder of sdcard in android
How to make a file hidden in android sd card?

Its not possible to give no access to that folder when device connected to pc.. Also its not possible on sdcard also,
But you can use different format for images that can be opened only from your application, or you can encrypt images.
Or if you want to hide images from showing them into gallery, you can put a blank file with name as ".nomedia" in your folder.
But its not possible cause if u read docs about WRITE_EXTERNEL_STORAGE permission you will understand what I am saying. :)

File path for android when using emulator

I am new to android. I am trying to download a file from server and save the file in a particular path. The application is working fine. However I am not able to find the path of the downloaded file. In the code I have given as
File output = new File("/data/data/com.test.firstApp/", fileName);
Where can i find the file on my system?

Don't use hard coded file paths. The framework will give you the base path of the area you want to save files to.
For the SD card, use Environment.getExternalStorageDirectory()
For local files, use Context.getFilesDir() (or Context.openFileOutput(String name, int mode), etc)
For local cache, use Context.getCacheDir()

Adding to Rich's answer, in the likely event you will end up writing to external storage make sure to include this permission in the manifest:
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

Check this page http://developer.android.com/guide/topics/data/data-storage.html
You can find there many methods how to save file. What is more you can also read something about good practices.
Cheers

Create a read-only folder in sdcard in android

I want to create a folder in sdcard in an android device and I want to set a folder permission for the creating folder. The folder permission should be that from only from my application this folder should be assessable. No other application should be able to access this folder. Is there any method to create this. Please provide any valid link for this.

sadly it is not possible to create read-only permissions for the sdcard. This is a part of Android's system design and won't be changed soon.

I am making an application in android and I want to make a ready only folder in sdcard.
This is not possible, sorry.

FAT32, the standard SD card file system, does not support file permissions. This means that any file is world readable and world writeable.

String SaveFolder = "/Ready";
String extStorageDirectory = Environment.getExternalStorageDirectory().toString();
File myFolder = new File(extStorageDirectory + Folder);
myFolder.mkdir();
This is a code to make a folder, and just like Tim said: it is not possible to create read-only permissions folder.

As others have said, you can't for the reasons specified.
I'm not exactly sure what you are trying to accomplish, but if you want to create a private file that can't be accessed by other apps, you can create in your app's "data" directory, by doing this,
OutputStream os = context.createFileOutput("myfile.ext", Context.MODE_PRIVATE);
Note that this is not the SD card, it's internal storage, so you aren't going to be able to create a very large file.

how can I copy files to the file system of android?

How can I copy files to the file system (place) in android? How can I access it?

copy files from android to local
adb pull /data/data/com.example.sample ./sample/
copy file to android from local
adb push ./sample/ /sdcard/sample/

I'm not sure if this is what you're asking, but here's another interpretation of your question:
You can place files in the assets folder in the project on your development machine. They will be bundled into the apk file and then access them through the AssetManager class. Something like this from within a Service or Activity class:
AssetManager am = getAssets();
InputStream is = am.open("filename");
This will allow you to read the contents of those files. I don't believe you can write to them though. There are other options for if you need to read and write files in your application's storage sandbox. This is done by calling openFileOutput(). I should note though that the user can always access the files on the device through ddms but other applications won't be able to access files stored in your application's storage sandbox.
Edit Based on your comment, you probably want to use
OutputStream out = openFileOutput("outfile");
to write to a file from your code. This code must be called from within an Activity or Service (something that extends Context). This file will be stored on the phone's file system and not on the sdcard. These files will not be accessible to the average user. If users know how to enable usb debugging then they will be able to access them and there is really no way around this.

You can use:
Environment.getExternalStorageDirectory()
That will give you /sdcard if your device has an sdcard, or something different in other cases. For example the Archos.

I took some time to research about android's system files earlier, but almost always with android x86, i found out that the /system folder inside android is read-only,
it is an image with format is SFS format, this is read-only image format of linux so i don't think you can copy some thing inside this folder. I not sure about rooted android. Hope it will help you.

You can probably hide your file in the sdcard by prefixing it with a dot (ex: .myfile)