Develop Reference

Create a file folder for app

The below code doesn't create a folder in my device.
String intStorageDirectory = context.getFilesDir().toString();
File folder = new File(intStorageDirectory, "test");
folder.createNewFile();;
I need a folder created for my app to store media, when user installs it. That folder should be visible on file explorer. How can i do it?

With the current snippet you created a file, you can also create folder by creating file but your current directory is the base folder, getFilesDir() points internal storage for your app which not visible nor accessible unless explicitly declared. You can create a folder and file by creating with new File().createNewFile() or create only folder using mkdirs() but you won't be able to display it using a file explorer app and that folder and files inside it will be deleted when/if user uninstalls your app.
To save files externally(This doesn't mean saving to SD Card) you can create directory and file with
File mediaStorageDir = new File(Environment.getExternalStorageDirectory(), folderName);
if (!mediaStorageDir.exists()) {
mediaStorageDir.mkdirs()
}
File mediaFile = new File(mediaStorageDir.getAbsolutePath() + File.separator + fileName);
And you need some kind of OutputStream to write data to that file.
Make sure that you ask <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" /> inside your AndroidManifest.xml file and ask write permission on runtime if your android:targetSdkVersion="23" or above

new File(context.getFielsDir(), "test").mkdirs();
createNewFile creates a file, not a folder. Using mkdirs instead of mkdir ensures that all parents exist. There's also no reason to go through a string when you already have a File.

Adding folder.mkdirs(); should work in place of folder.createNewFile(); And don't forget to add the permissions.
This will create a folder in you data directory.
And just a suggestion , if you want to store media in a SD card folder maybe Environment.getExternalStorageDirectory() is good.

Accessing SD CARD and doing FILE IO Operations

I am trying to create a folder and then after that do some file IO operations!
I am using a sony Xperia Z to test this out!
I know right now I've hardcoded the location but it doesn't let me create folders!
File appPath = new File("/storage/sdcard1/folder");
if (!appPath.exists()) {
appPath.mkdirs();
}
I am using a targetSdkVersion of 22
And having lollipop on my phone.
I tried
appPath.mkDir();
as well but all this gives a value of False.
And i have added permissions to manifest
<uses-permission name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission name="android.permission.READ_EXTERNAL_STORAGE" />
And I tried many different open source file manager but none are able to create folders, But ES file Manager is able to create folders and do File IO operations!

Don't hardcode global paths like /sdcard, use Environment.getExternalStorageDirectory() and related methods instead. Here is a working sample.
public static String getNewFolderPath() {
File folder = new File(Environment.getExternalStorageDirectory()
.toString() + File.separator + "folder");
if (!folder.exists())
folder.mkdirs();
return folder.getAbsolutePath();
}
EDIT:
For more info check:
Find an external SD card location
#CommonsWare Answer
#Aleadam Answer
Hope it helps!

create visible folder sdcard, Android

I'm developping an application where I need to create new folders/files in the sdcard. The thing is I can see them using a root explorer but not with the default one which comes with Android.
I've taken a look at several similar questions here but don't seem to work for me.
For sure, I'm using in my manifest this:
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
and I'm writing all the Files using:
String path = Environment.getExternalStorageDirectory() + "/FolderName/FileName.format"
but as I said, these new folders/files remained hidden and can only be seen using a root explorer. Neither the folder nor file name starts with "."
Thanks in advance.

Try using mkDirs()
File dir = new File(fullPath);
if (!dir.exists()) {
dir.mkdirs();
}

Create folder in sd card

Alright so I created 2 folders in the SD card using the following code:
String folderPath = Environment.getExternalStorageDirectory() + "/AllAroundMe/Images/";
File file = new File(folderPath);
if(!file.exists())
{
if(file.mkdirs());
Log.d("MyTag","Successfully created folders");
}
I tested this program and it really works, the logcat prints the success message above.
But if I navigate to my sd card I don't see "AllAroundMe" folder.
How can I access that folder from my computer?

Try this
Open DDMS perspective -> File Explorer - > mnt -> sdcard

Go to Android DDMS FIleExplorer-->mnt-->sdcard--> and search for your sdcard folder which is created by you

Just check u can`t give the permission in manifest file in your Application just add the permission of this.
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
Than run your own code the folder has been create in sdcard ok check this.

First i hope you have given the External Storage permission in your Manifest.xml
Do something like this... i know what you did right, but still i prefer this approach.
File f = new File("/sdcard/AllAroundMe/Images/");
Now browse your sdcard from you pc, i am sure you will find the folder.

Slashes removed from calls to File.mkdirs()

As the title suggests, I am trying to create a folder on Android, but all of the slashes have been removed from it.
For some more background information:
Specifically, I am trying to create a directory to store my application's users' files. These files must be accessible to the user from a file manager (such as File Manager HD) because the application does not support full file management. Using the standard from API level 8+, I reference the root of the publicly accessible folder with Environment.getExternalStoragePublicDirectory(). I then try to create a folder located at DCIM > Sketchbook > [the name of the sketch] using File.mkdirs(). For more information, see the code below.
I have already:
checked to make sure that the SD card is mounted, readable, and writable
enabled the permission WRITE_EXTERNAL_STORAGE
tried using File.mkdir() for every file in the hierarchy up to the folder location
tried using /, \\, File.separatorChar, and File.separator as folder separators
Code:
boolean success = true;
//The public directory
File publicDir = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DCIM);
//The location of the sketchbook
File sketchbookLoc = new File(publicDir + "Sketchbook" + File.separator);
//The location of the sketch
//getGlobalState().getSketchName() returns the name of the sketch: "sketch"
File sketchLoc = new File(sketchbookLoc + getGlobalState().getSketchName() + File.separator);
if(!sketchLoc.mkdirs()) success = false;
//Notify the user of whether or not the sketch has been saved properly
if(success)
((TextView) findViewById(R.id.message)).setText(getResources().getText(R.string.sketch_saved));
else
((TextView) findViewById(R.id.message)).setText(getResources().getText(R.string.sketch_save_failure));
With various incarnations of the aforementioned tests (the ones that actually worked), I have received a consistent result: I get a new folder in DCIM whose name corresponds to the combination of all of the folders that should have been hierarchical parents of it. In other words, I have created a new directory, but all of the folder separators have been removed from it.
Now, I ask you:
Am I attempting to save the user data in the correct location? Is there another way that I should be doing this?
Is it even possible to create new folders in the DCIM folder? Does Android prevent it?
Is this problem specific to me? Is anyone else able to create a folder in the DCIM folder?
Am I using the right folder separators?
Is there something else that I am absolutely, completely, and utterly missing?
Now that I am done typing, and you are done reading my (excessively long) question, I hope that I can find some sort of answer. If you need clarification or more information, please say so.
EDIT: An example of the created folder is "DCIMSketchbooksketch", where it should be "DCIM/Sketchbook/sketch".

don't use
File sketchbookLoc = new File(publicDir + "Sketchbook" + File.separator);
but
File sketchbookLoc = new File(publicDir , "Sketchbook");
because publicDir.toString() will not end with a file separator (even if you declared it that way). toString() gives the canonical name of the file.
So your source becomes :
//The location of the sketchbook
File sketchbookLoc = new File(publicDir , "Sketchbook" );
//The location of the sketch
File sketchLoc = new File(sketchbookLoc , getGlobalState().getSketchName() );