I have an application that make me choose a file through a file explorer(the file is stored on the sd), and then reads it.
I want to modify it, so it has the file directly into the app and reads the file from "inside". Where I have to put the file into the project? How can I access it?
You can save a file inside your project by using the following code:
File cDir = getApplication().getExternalFilesDir(null); File saveFilePath = new File(cDir.getPath() + "/" + "yourfilename"); You can see the saved file inside "files" folder of your application package name in your device.
Try the following path in your device:
File manager >> Android >> data >> "your package name" >> files >> new file. 
Yes, you can put your file into /assets folder, and retrieve as follows:
AssetManager assetManager = getAssets(); InputStream instream = assetManager.open("file.txt"); or res/raw folder:
InputStream raw = getResources().openRawResource(R.raw.file); If you want to modify it, you'll be able only to write a file into External storage (e.g. sdcard), or into Internal storage (under your application folder data/data/package_name/). If you store your file into External storage it will persist until user manually or programmatically deletes the file. But if you store this file into Internal storage, it will be deleted if user deletes an app, or clear an application cache.
File myExternalFile; if (!isExternalStorageAvailable() || isExternalStorageReadOnly()) { saveToExternalStorage.setEnabled(false); } else { myExternalFile = new File(getExternalFilesDir(filepath), filename); } save External Storage (FileOutputStream )
try { FileOutputStream fos = new FileOutputStream(myExternalFile); fos.write(myInputText.getText().toString().getBytes()); fos.close(); } catch (IOException e) { e.printStackTrace(); } myInputText.setText(""); responseText.setText("Saved to External Storage.(StorageFile.txt)"); Get External Storage (FileInputStream )
try { FileInputStream fis = new FileInputStream(myExternalFile); BufferedReader br = new BufferedReader( new InputStreamReader(fis)); String strLine; while ((strLine = br.readLine()) != null) { myData = myData + strLine; } in.close(); } catch (IOException e) { e.printStackTrace(); } myInputText.setText(myData); responseText .setText("Data retrieved from Internal Storage.(StorageFile.txt)"); 
