Develop Reference

need help saving image files

I am trying to save signature pad image to file but my app doesn't seem to be creating the directory in storage/emulated/0
this is what I am using to create the folder...
String DIRECTORY = Environment.getExternalStorageDirectory().getPath() + "/Signature/";
String pic_name = new SimpleDateFormat("yyyyMMdd_HHmmss",Locale.getDefault()).format(new Date());
String StoredPath = DIRECTORY + pic_name + ".png";
and this is what I am using to create the directory
file = new File(DIRECTORY);
if (!file.exists()) {
file.mkdir();
}
and finally, this is where the file is saved...
public void save(View v, String StoredPath) {
Log.v("log_tag", "Width: " + v.getWidth());
Log.v("log_tag", "Height: " + v.getHeight());
if (bitmap == null) {
bitmap = Bitmap.createBitmap(canvasLL.getWidth(), canvasLL.getHeight(), Bitmap.Config.RGB_565);
}
Canvas canvas = new Canvas(bitmap);
try {
// Output the file
FileOutputStream mFileOutStream = new FileOutputStream(StoredPath);
v.draw(canvas);
// Convert the output file to Image such as .png
bitmap.compress(Bitmap.CompressFormat.PNG, 90, mFileOutStream);
mFileOutStream.flush();
mFileOutStream.close();
} catch (Exception e) {
Log.v("log_tag", e.toString());
}
}
Please note that this is not my own code...
(Basically a copy and paste from)
http://demonuts.com/android-capture-signature-using-canvas/
The pad works fine, I can write on it, but it won't save :(
When I send it to a Toast I can return the full directory and file name of Storage/emulated/0/Signature/20191101_a time stamp.png but it wont save on device.
Any ideas??

Declare the permissions in AndroidManifest.xml file, To grant external storage read write permission.
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>
For Android OS version > 6.0, you require run time permissions as well.
// Check whether this app has write external storage permission or not.
int permission = ContextCompat.checkSelfPermission(ExternalStorageActivity.this, Manifest.permission.WRITE_EXTERNAL_STORAGE);
// If do not grant write external storage permission.
if(permission!= PackageManager.PERMISSION_GRANTED)
{
// Request user to grant write external storage permission.
ActivityCompat.requestPermissions(ExternalStorageActivity.this, new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE}, REQUEST_CODE_WRITE_EXTERNAL_STORAGE_PERMISSION);
}

Thank you all for the help... my problem was creating a drive to save to. I found my answer at https://www.quora.com/How-do-I-create-a-folder-in-internal-and-external-storage-programmatically-in-an-Android-app
I should be able to create and save the file now thanks

Problem saving image in external storage on android

I am writing a camera application for the android platform. I am using the CameraKitView Library for producing my camera view. Everything else including accessing the camera is working as expected except for actually capturing and saving the image. minimum sdk is 15 and target sdk and compile sdk is 28. The code for saving the image is as shown below
cameraKitView.captureImage(new CameraKitView.ImageCallback() {
#Override
public void onImage(CameraKitView cameraKitView, byte[] photo) {
File savedPhoto = new File(Environment.getExternalStorageDirectory(), "pchk.jpg");
try{
FileOutputStream outputStream = new FileOutputStream(savedPhoto.getPath());
outputStream.write(photo);
outputStream.close();
}catch (java.io.IOException e){
e.printStackTrace();
}
}
});
Thank you in advance for your assistance

First of all verify that your file or folder where you want to save a file is exists or not, if not create them
capturedFolderPath is a path of the folder where you want to create the file
File folderFile = new File(capturedFolderPath)
if (!folderFile.exists()) {
folderFile.mkdirs();
}
String imageNameToSave = "xyz.jpg";
String imagePath = capturedFolderPath
+ File.separator + imageNameToSave + ".jpg";
File photoFile = new File(imagePath);
if (!photoFile.exists()) {
photoFile.createNewFile();
}
after creating write the bytes on the file like this
FileOutputStream outputStream = new FileOutputStream(photoFile);
outputStream.write(bytes);
outputStream.close();

Android: how to write a file to internal storage

I am developing a simple android application and I need to write a text file in internal storage device. I know there are a lot of questions (and answers) about this matter but I really cannot understand what I am doing in the wrong way.
This is the piece of code I use in my activity in order to write the file:
public void writeAFile(){
String fileName = "myFile.txt";
String textToWrite = "This is some text!";
FileOutputStream outputStream;
try {
outputStream = openFileOutput(fileName , Context.MODE_PRIVATE);
outputStream.write(textToWrite.getBytes());
outputStream.close();
} catch (Exception e) {
e.printStackTrace();
}
}
I really cannot understand which mistake I am doing. In addition, I have tried this project on my emulator in Android Studio and my phone in order to understand where I am doing something wrong but even with that project no file is written neither on the phone or on the emulator.
EDIT:
I know that no file is written to my internal storage because I try to read the content of the file, after I have written to it, with this code:
public void ReadBtn(View v) {
//reading text from file
try {
FileInputStream fileIn=openFileInput("myFile.txt");
InputStreamReader InputRead= new InputStreamReader(fileIn);
char[] inputBuffer= new char[READ_BLOCK_SIZE];
String s="";
int charRead;
while ((charRead=InputRead.read(inputBuffer))>0) {
String readstring=String.copyValueOf(inputBuffer,0,charRead);
s +=readstring;
}
InputRead.close();
textmsg.setText(s);
} catch (Exception e) {
e.printStackTrace();
}
}
Nothing is shown at all.

Use the below code to write a file to internal storage:
public void writeFileOnInternalStorage(Context mcoContext, String sFileName, String sBody){
File dir = new File(mcoContext.getFilesDir(), "mydir");
if(!dir.exists()){
dir.mkdir();
}
try {
File gpxfile = new File(dir, sFileName);
FileWriter writer = new FileWriter(gpxfile);
writer.append(sBody);
writer.flush();
writer.close();
} catch (Exception e){
e.printStackTrace();
}
}
Starting in API 19, you must ask for permission to write to storage.
You can add read and write permissions by adding the following code to AndroidManifest.xml:
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
You can prompt the user for read/write permissions using:
requestPermissions(new String[]{WRITE_EXTERNAL_STORAGE,READ_EXTERNAL_STORAGE}, 1);
and then you can handle the result of the permission request in onRequestPermissionsResult() inside activity called from it.

no file is written neither on the phone or on the emulator.
Yes, there is. It is written to what the Android SDK refers to as internal storage. This is not what you as a user consider to be "internal storage", and you as a user cannot see what is in internal storage on a device (unless it is rooted).
If you want to write a file to where users can see it, use external storage.
This sort of basic Android development topic is covered in any decent book on Android app development.

Save to Internal storage
data="my Info to save";
try {
FileOutputStream fOut = openFileOutput(file,MODE_WORLD_READABLE);
fOut.write(data.getBytes());
fOut.close();
Toast.makeText(getBaseContext(), "file saved", Toast.LENGTH_SHORT).show();
}
catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
Read from Internal storage
try {
FileInputStream fin = openFileInput(file);
int c;
String temp="";
while( (c = fin.read()) != -1){
temp = temp + Character.toString((char)c);
}
tv.setText(temp);
Toast.makeText(getBaseContext(), "file read", Toast.LENGTH_SHORT).show();
}
catch(Exception e){
}

Android 11 Update
Through Android 11 new policies on storage, You cannot create anything in the root folder of primary external storage using Environment.getExternalStorageDirectory() Which is storage/emulated/0 or internal storage in file manager. The reason is that this possibility led to external storage being just a big basket of random content. You can create your files in your own applications reserved folder storage/emulated/0/Android/data/[PACKAGE_NAME]/files folder using getFilesDir() but is not accessible by other applications such as file manager for the user! Note that this is accessible for your application!
Final solution (Not recommended)
By the way, there is a solution, Which is to turn your application to a file manager (Not recommended). To do this you should add this permission to your application and the request that permission to be permitted by the user:
<uses-permission android:name="android.permission.MANAGE_EXTERNAL_STORAGE" />
Thoriya Prahalad has described how to this job in this stackoverflow post.

To view files on a device, you can log the file location >provided by methods such as File.getAbsolutePath(), and >then browse the device files with Android Studio's Device >File Explorer.
I had a similar problem, the file was written but I never saw it. I used the Device file explorer and it was there waiting for me.
String filename = "filename.jpg";
File dir = context.getFilesDir();
File file = new File(dir, filename);
try {
Log.d(TAG, "The file path = "+file.getAbsolutePath());
file.createNewFile();
} catch (Exception e) {
e.printStackTrace();
}
return true;

Have you requested permission to write to external storage?
https://developer.android.com/training/basics/data-storage/files.html#GetWritePermission
Perhaps your try\catch block is swallowing an exception that could be telling you what the problem is.
Also, you do not appear to be setting the path to save to.
e.g: Android how to use Environment.getExternalStorageDirectory()

To write a file to the internal storage you can use this code :
val filename = "myfile"
val fileContents = "Hello world!"
context.openFileOutput(filename, Context.MODE_PRIVATE).use {
it.write(fileContents.toByteArray())
}

This Answer worked for me for android 11+ !! check it out, hopefully it'll work for you too
https://stackoverflow.com/a/66366102/16657358[1]
[(btw, int SDK_INT = 30; it confused me lol so thought i should mention)]

How to write file to sd-card? (Android) No errors, but nothing written

I'm new to developing android apps. And already overchallenged with my first project. My app should be able to save a list of EditText fields to a text file by clicking a "save"-Button.
But I got no success to write a file to my SD-card.
My code:
(function in MainActivity.java called by the button)
public void saveData(View view){
try{
File sdcard = Environment.getExternalStorageDirectory();
// to this path add a new directory path
File dir = new File(sdcard.getAbsolutePath() + "/myapp/");
// create this directory if not already created
dir.mkdir();
// create the file in which we will write the contents
File file = new File(dir, "datei.txt");
FileOutputStream os = new FileOutputStream(file);
String data = "some string";
os.write(data.getBytes());
os.flush();
os.close();
}
catch (IOException e){
Log.e("com.sarbot.FitLogAlpha", "Cant find Data.");
}
}
With Google I found another way:
public void saveData3(View view){
FileWriter fWriter;
File sdCardFile = new File(Environment.getExternalStorageDirectory() + "/datafile.txt");
Log.d("TAG", sdCardFile.getPath()); //<-- check the log to make sure the path is correct.
try{
fWriter = new FileWriter(sdCardFile, true);
fWriter.write("CONTENT CONTENT UND SO");
fWriter.flush();
fWriter.close();
}catch(Exception e){
e.printStackTrace();
}
}
In my manifest.xml I set the permissions:
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
And the function from developer guide returns me True -> SD-card is writable.
/* Checks if external storage is available for read and write */
public boolean isExternalStorageWritable() {
String state = Environment.getExternalStorageState();
if (Environment.MEDIA_MOUNTED.equals(state)) {
return true;
}
return false;
}
In the res/layout/activity_main.xml are some TextViews and EditText and a save button with android:onClick="saveData" argument. The function is called. The SD-card is writable. And no IO errors. But after pressing the button (without error) there is still no new file on my SD-card. I already tried to create the file manually and just append but nothing changed. I tried some other function with BufferedWriter too .. but no success.
I'm running my Sony Xperia E with USB-Debug mode. Unmount and mounted the SD-card on my PC but cant find the file. Maybe it is only visible for the phone? It doesn't exist? I don't know what to do because I get no errors. I need the content of this file on my computer for calculations.
:EDIT:
The problem was not in the code.. just in the place I looked up. The externalStorage -> sdCard seems to be the internal and the removable sdcard is the -> ext_card.

After this line,
File file = new File(dir, "datei.txt");
Add this code
if ( !file.exists() )
{
file.createNewFile(); // This line will create new blank line.
}

os.flush() is missing in your code. Add this snippet before os.close()

Save picture while Camera is in stopPreview mode

BACKGROUND
Hey so I have a camera that I have implemented myself in code. This means I access and control the camera hardware and use it to save pictures. I can save the picture using the Camera.takePicture() function when the camera is running: running means Camera.startPreview();
PROBLEM
My problem is that I want to be able to save the image also when the camera image is frozen: frozen is when Camera.stopPreview(); is called.When frozen I can see the image in my layout but how do I access it? Where is the image saved so that I might be able to modify it later?
Thanks in advance!
------------------Update 1
jpeg bla;
public class jpeg implements PictureCallback{
public void onPictureTaken(byte[] data, Camera camera) {
g_data = data;
}
}
This is part of my code. Here I am trying to write the data that would originally be saved to a global variable. However the value of g_data remains null and I am unable to set a breakpoint inside the onPictureTaken() call back function.
------------------Update 2
FileOutputStream outStream = null;
try {
// generate the folder
File imagesFolder = new File(Environment.getExternalStorageDirectory(), "MirrorMirror");
if( !imagesFolder.exists() ) {
imagesFolder.mkdirs();
}
// generate new image name
SimpleDateFormat formatter = new SimpleDateFormat("HH_mm_ss");
Date now = new Date();
String fileName = "image_" + formatter.format(now) + ".jpg";
// create outstream and write data
File image = new File(imagesFolder, fileName);
outStream = new FileOutputStream(image);
outStream.write(data);
outStream.close();
Log.d(TAG, "onPictureTaken - wrote bytes: " + data.length);
} catch (FileNotFoundException e) { // <10>
//Toast.makeText(ctx, "Exception #2", Toast.LENGTH_LONG).show();
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} finally {}
I used this code previously to save the file from the camera onPictureTaken() function. The key here is the byte[] data which I need to save and save later. However like I said I just get a null when I check it in the debugger.

Camera.takePicture never looks at the view you specified as previewDisplay. Actually, it isn't an ImageView, but a SurfaceView, and there are no API to read pixels from it.
You can call takePicture() preemptively just before you stopPreview(). Later, if you find out that you don't need the picture, just discard it.

Ok so the exact way to do this is to take the picture just before stopPreview() and save it to a temporary file. Actually with this implementation you never call stopPreview()(otherwise it will crash) since the takePicture() function stops the preview automatically.
try {
File temp = File.createTempFile("temp", ".jpg");
} catch (IOException e) {
e.printStackTrace();
}
Now that we have the temporary file saved we will access it later and move it to our new desired file location.
How to copy file.
temp.deleteOnExit();
be sure to call deleteonExit() so that Android deletes the file after the app is closed(if so desired).