Develop Reference

How can I get file path on raw resources in Android Studio?

I have been using this tutorial to make some face detections on picture. The problem is when I getting the file path that used on java
String xmlFile = "E:/OpenCV/facedetect/lbpcascade_frontalface.xml";
CascadeClassifier classifier = new CascadeClassifier(xmlFile);
How can I translate on android studio. I try put my lbpcascade_frontalface.xml on raw resources. CascadeClassifier is a class that opencv library provided. The only problem is they only loaded string path (on xmlfile).
this is my code.
String pathtoRes = getRawPathAtempt2(context);
CascadeClassifier cascadeClassifier = new CascadeClassifier();
cascadeClassifier.load(pathtoRes);
I translated to some method like this.
public String getRawPathAtempt2(Context context) {
return "android.resource://" + context.getPackageName() + "/raw/" + "lbpcascade_frontalface.xml";
}
I get the asertions error by opencv that tell me the file is null. Thats mean I had been wrong when I used file path on my method. how can I get file path on raw resources? help me please I have been stuck for several days now

how can i get file path on raw resources?
You can't. There is no path. It is a file on your development machine. It is not a file on the device. Instead, it is an entry in the APK file that is your app on the device.
If your library supports an InputStream instead of a filesystem path, getResources().openRawResource() on a Context to get an InputStream on your raw resource.

This is how i solved the problem with #CommonWare Answer
i'm using input stream to get file
is = context.getResources().openRawResource(R.raw.lbpcascade_frontalface);
so make the file will be opened and i will make a point to the File class
File cascadeDir = context.getDir("cascade", Context.MODE_PRIVATE);
mCascadeFile = new File(cascadeDir, "lbpcascade_frontalface.xml");
and then i make a search to the path file using getAbsolutePath like this
cascadeClassifier.load(mCascadeFile.getAbsolutePath());
take a look at my full code
try {
is = context.getResources().openRawResource(R.raw.lbpcascade_frontalface);
File cascadeDir = context.getDir("cascade", Context.MODE_PRIVATE);
mCascadeFile = new File(cascadeDir, "lbpcascade_frontalface.xml");
os = new FileOutputStream(mCascadeFile);
byte[] buffer = new byte[4096];
int bytesRead;
while ((bytesRead = is.read(buffer)) != -1) {
os.write(buffer, 0, bytesRead);
}
is.close();
os.close();
cascadeClassifier.load(mCascadeFile.getAbsolutePath());
} catch (IOException e) {
Log.i(TAG, "face cascade not found");
}

Uri video = Uri.parse("android.resource://com.test.test/raw/filename");
Using this you can access the file in raw folder, if you want to access the file in asset folder use this URL...
file:///android_asset/filename
Make sure you don't add the extension to the filename. E.g. "/movie" not "/movie.mp4".
Refer to this link:
Raw folder url path?

We can use this Alternative method for finding the path of Files in Raw Folder.
InputStream inputStreamdat=getResources().openRawResource(R.raw.face_landmark_model);
File model=getDir("model", Context.MODE_PRIVATE);
File modelFile=new
File(model,"face_landmark_model.dat");
FileOutputStream os1 = new
FileOutputStream(modelFile);
byte[] buffer1 = new byte[4096];
int bytesRead1;
while ((bytesRead1=inputStreamdat.read(buffer1))!=-1) {
os1.write(buffer1, 0, bytesRead1);
}
inputStreamdat.close();
os1.close();
You Can Use
modelFile.getAbsolutePath()); For getting the Path

For loop causing android app to crash

i'm having trouble figuring out why my app is crashing every time i open it. It's only when I uncomment the for loop.
I'm using this idea here to copy files from one directory to another
How to programmatically move, copy and delete files and directories on SD?
however this part (i tried both this way and the same way as in the link above, using children string, etc)
for (File file : files)
{
CopyFile(file, target);
}
keeps causing my application to crash. I tried commenting out just this part and the app runs fine (it doesnt copy anything however as its not accessing a file)
Any ideas?
private void CopyFile(File source, File target) throws IOException {
if (source.isDirectory()){
File[] files = source.listFiles();
for (File file : files)
{
CopyFile(file, target);
}
} else {
InputStream in = new FileInputStream(source);
OutputStream out = new FileOutputStream(Environment.getExternalStorageDirectory());
byte[] buf = new byte[1024];
int len;
while ((len = in.read(buf)) > 0){
out.write(buf, 0, len);
}
in.close();
out.close();
}

You can't read anything in /data/data except from subdirectories controlled by your app.
/data/data/*packagename*/files
is the path returned by Context.getFilesDir()
/data
is the path returned by Environment.getDataDirectory().
Where exactly do you expect the files to be, and how did they get there originally?

Android work with db file from SD card

I wrote an app which logged data and saved it via SQL into a .db File. I had a method copying it from internal memory to SD card.
Now i wrote a second app, which needs to work with this particular .db file. As i think, that apps can't get access to package files from other apps
(in this case
/data/data/app1_package/databases/my_database.db
)
i need somehow to work with my DB on the SD Card. How do i do that?
Can i use this path in my SQLiteHelper class? Should i copy it from SD to my package, is that even possible (access rights etc.)?
I'm a beginner in databases, some help would be nice.

You can open any readable file path as a database:
File dbFile = new File( Environment.getExternalStorageDirectory(), "myfile.db" );
SQLiteDatabase db = SQLiteDatabase.openOrCreateDatabase(dbFile,null,null);
Note: check if sd-card is mounted before using this code.

yes place the DB file in your assets folder and get it this way :
DB_PATH="/data/data/app1_package/databases/my_database.db"
in your create :
is = getAssets().open("Meaniningss.db");
write(is);
the method :
public void write(InputStream is) {
try {
OutputStream out = new FileOutputStream(new File(DB_PATH));
int read = 0;
byte[] bytes = new byte[1024];
while ((read = is.read(bytes)) != -1) {
out.write(bytes, 0, read);
}
is.close();
out.flush();
out.close();
System.err.println(out + "\n");
} catch (IOException e) {
e.printStackTrace();
}
}

Reading files from a ZIP file in your Android assets folder

I'm reading files from a ZIP file that's located in my Android assets folder using ZipInputStream: it works, but it's really slow, as it has to read it sequentially using getNextEntry(), and there are quite a lot of files.
If I copy the ZIP file onto the SD card, reading is really fast when using ZipFile.getEntry, but I didn't find a way to use ZipFile with the asset file!
Is there any way to access the ZIP in the asset folder in a speedy way? Or do I really have to copy the ZIP to the SD card?
(BTW, in case anybody wonders why I'm doing this: the app is larger than 50 MB, so in order to get it in the Play Store I have to use Expansion APKs; however, as this app should also be put into the Amazon App Store, I have to use another version for this, as Amazon doesn't support Expansion APKs, naturally... I thought that accessing a ZIP file at two different locations would be an easy way to handle this, but alas...)

This works for me:
private void loadzip(String folder, InputStream inputStream) throws IOException
{
ZipInputStream zipIs = new ZipInputStream(inputStream);
ZipEntry ze = null;
while ((ze = zipIs.getNextEntry()) != null) {
FileOutputStream fout = new FileOutputStream(folder +"/"+ ze.getName());
byte[] buffer = new byte[1024];
int length = 0;
while ((length = zipIs.read(buffer))>0) {
fout.write(buffer, 0, length);
}
zipIs.closeEntry();
fout.close();
}
zipIs.close();
}

You can store the uncompressed files directly in assets (i.e. unpack the zip into assets/ folder). This way, you can access the files directly and they will be compressed anyway when you build the APK.

You can create a ZipInputStream in the following way :
ZipInputStream zipIs = new ZipInputStream(context.getResources().openRawResource(your.package.com.R.raw.filename));
ZipEntry ze = null;
while ((ze = zipIs.getNextEntry()) != null) {
FileOutputStream fout = new FileOutputStream(FOLDER_NAME +"/"+ ze.getName());
byte[] buffer = new byte[1024];
int length = 0;
while ((length = zipIs.read(buffer))>0) {
fout.write(buffer, 0, length);
}
zipIs .closeEntry();
fout.close();
}
zipIs .close();

SQLite Database not showing up in File Explorer

I have an SQLite database in my application. When I go to check if the database is created or not in File Explorer, there is no any database file within the data folder. It didn't even show up using the adb shell command. Does this mean that the database hasn't been created yet? Any suggestions on how to solve this?

If you are using an actual device, you will not be able to see or access it from outside unless you root your phone.
If you are using the emulator, the DDMS view will let you navigate to it and pull it from there.
Or, you could have an issue with creating your DB. Without seeing your code we cannot tell.
EDIT
If you want to get the file off of a real device, you'll need to implement a method to copy it from your data directory to someplace where you do have access (such as your SD card). This would do the trick:
public void backup() {
try {
File sdcard = Environment.getExternalStorageDirectory();
File outputFile = new File(sdcard,
"YourDB.bak");
if (!outputFile.exists())
outputFile.createNewFile();
File data = Environment.getDataDirectory();
File inputFile = new File(data, "data/your.package.name/databases/yourDB");
InputStream input = new FileInputStream(inputFile);
OutputStream output = new FileOutputStream(outputFile);
byte[] buffer = new byte[1024];
int length;
while ((length = input.read(buffer)) > 0) {
output.write(buffer, 0, length);
}
output.flush();
output.close();
input.close();
} catch (IOException e) {
e.printStackTrace();
throw new Error("Copying Failed");
}
}