How to create a directory on the internal storage upon installation of the Android application?

Question

I want to have a single folder where I will put all the resources I'm going to need and I want it on the internal storage. Since I want this directory to be created only once, I found out that I should create it in the main activity of the application:

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    File directory = context.getDir("mydir", Context.MODE_PRIVATE);
    Log.d("directory", directory.getAbsolutePath().toString());
} 

It seems ok as this is what I was able to find on the internet, however I am receiving loads of erros, I can get to the log for the directory path and the application doesn't start. Any idea why?

Also, if I work with internal storage every time when I run my application from Eclipse to my phone, does it automatically deletes the previous one together with its resources or I've to do that manually?

Answer 1

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();

Answer 2

IF you would like to store on the external storage SD card instead, you need to have this

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

In your AndroidManifest.xml file

Also this for working with the storage:

File direct = new File(Environment.getExternalStorageDirectory()+"/folder");

if(!direct.exists()) {
     if(direct.mkdir()); //directory is created;
}