Develop Reference

saving a captured image to external storage failed

I want to save my captured images to a specific directory (/sdcard/DCIM/FokusStacker) with the following method. I have tried different Locations, but none of them worked.
private void capturePicture(){
File dir = new File("/sdcard/DCIM/FokusStacker");
String fileName = "IMG_"+ System.currentTimeMillis();
File file = new File(dir,fileName);
Log.d(TAG, "capturePicture: DIRECTORY: "+dir.getAbsolutePath());
ImageCapture.OutputFileOptions outputFileOptions =
new ImageCapture.OutputFileOptions.Builder(file).build();
imageCapture.takePicture(outputFileOptions, ContextCompat.getMainExecutor(this), new ImageCapture.OnImageSavedCallback() {
#Override
public void onImageSaved(#NonNull ImageCapture.OutputFileResults outputFileResults) {
Log.d(TAG, "onImageSaved: SAVED");
return;
}
#Override
public void onError(#NonNull ImageCaptureException exception) {
Log.d(TAG, "onError: FAILED");
return;
}
});
}
These are the Permission i've included:
<uses-permission android:name="android.permission.CAMERA" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
And i also tried saving it to the internal storage.
Code Snippet for to get the local directoryof the App for the file:
File dir = getApplicationContext().getFilesDir();
Can anyone please guide me how to do this?
I am a little new to android so please, I would appreciate if I can have a detailed procedure.

Update android debug app causes "app is not installed" (no google play)

I am trying to make possible for users to update ann app from device. We have a server where from user can download apk file with new version of an app.
Here is the code which starts after button pressed:
Handler handler = new Handler(Looper.getMainLooper());
Thread thread = new Thread(new Runnable() {
#Override
public void run() {
File folder = new File(getExternalFilesDir(Environment.DIRECTORY_DOWNLOADS).toString());
File file = new File(folder.getAbsolutePath(), "localdb.apk");
final Uri uri = (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) ?
FileProvider.getUriForFile(MainActivity.this, BuildConfig.APPLICATION_ID + ".provider", file) :
Uri.fromFile(file);
if (file.exists())
file.delete();
//url to get app from server
String url = Names.UPDATE_URL;
InputStream input = null;
OutputStream output = null;
HttpURLConnection connection = null;
try {
URL sUrl = new URL(url);
connection = (HttpURLConnection) sUrl.openConnection();
connection.connect();
// download the file
input = connection.getInputStream();
output = new FileOutputStream(file);
byte data[] = new byte[4096];
int count;
while ((count = input.read(data)) != -1) {
// allow canceling with back button
output.write(data, 0, count);
}
} catch (Exception e) {
e.printStackTrace();
} finally {
try {
if (output != null)
output.close();
if (input != null)
input.close();
} catch (IOException ignored) {
}
if (connection != null)
connection.disconnect();
}
handler.post(new Runnable() {
#Override
public void run() {
Intent install = new Intent(Intent.ACTION_INSTALL_PACKAGE)
.setData(uri)
.addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);
startActivity(install);
}
});
}
});
thread.start();
Here is what i have in manifest:
...<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
<uses-permission android:name="android.permission.FOREGROUND_SERVICE" />
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED" />
<uses-permission android:name="android.permission.QUICKBOOT_POWERON" />
<uses-permission android:name="android.permission.REQUEST_INSTALL_PACKAGES"/>
...
<provider
android:name="androidx.core.content.FileProvider"
android:authorities="ru.mob.myapp.provider"
android:exported="false"
android:grantUriPermissions="true">
<meta-data
android:name="android.support.FILE_PROVIDER_PATHS"
android:resource="#xml/provider_paths"/>
</provider>
...
and finally an xml file provider_paths:
<?xml version="1.0" encoding="utf-8"?>
<paths>
<external-path name="external_files" path="."/>
</paths>
So, everything works fine, I download apk with new version, it is named same as already installed,
system asks me to install (update) my application, but when everything is almoust done I get "App is not installed" message without any details.
Does anyone have a solution, hint, adviсe?

Writing permission on android filesystems

I should generate a .pdf file inside the android data folder to use the Java code below, with the permissions enabled in the XML manifest file. But when I run the code I have the following exception. The application has different permissions within the manifest, It should all be configured correctly, I state that the application I'm testing on an old Android 4. How can I solve this? and what is it due to?
Exception: error: java. I. FileNotFoundException: /data/my.pdf:
open failed: EACCES (Permission denied)
Code:
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
<uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE " />
public static Boolean GeneratePDF(String base64) {
Boolean ret = true;
try {
String direttorio=""+Environment.getDataDirectory().getAbsolutePath();
final File dwldsPath = new File(direttorio + "/" + "my.pdf");
byte[] pdfAsBytes = Base64.decode(base64, 0);
FileOutputStream os;
os = new FileOutputStream(dwldsPath, false);
os.write(pdfAsBytes);
os.flush();
os.close();
} catch (Exception ex) {
System.out.println("\n Errore Generazione File: "+ex);
ret = false;
}
return ret;
}

you have to give Write permission at run time.
It can be achieved something as following...
public class MainActivity extends AppCompatActivity implements ActivityCompat.OnRequestPermissionsResultCallback{
private static final int REQUEST_WRITE_PERMISSION = 111;
#Override
public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults) {
if (requestCode == REQUEST_WRITE_PERMISSION && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
GeneratePDF("your String name");
}
}
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
requestPermission();
}
private void requestPermission() {
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
requestPermissions(new String[]{android.Manifest.permission.WRITE_EXTERNAL_STORAGE}, REQUEST_WRITE_PERMISSION);
} else {
GeneratePDF("your String name");
}
}
}

Replace this line
String direttorio=""+Environment.getDataDirectory().getAbsolutePath();
To:
String direttorio= Environment.getExternalStorageDirectory().getAbsolutePath();
final File dwldsPath = new File(direttorio + "/" + my.pdf");

if you're using Android 6.0 and above,
there could be 2 ways:
1 if you're making only for demo purpose you can manually give permission to app
by going in settings->apps->permissions. Then allow all permission which are
required.
2 you've to implement runtime permissions so that user can allow it runtime.

Writing to external storage?

I have written codes from the tutorials of SLIDENERD to save info in different areas as internal cache,External cache,Private information and public information with the following codes.
EditText uname,pwd;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
uname=(EditText)findViewById(R.id.editText);
pwd=(EditText)findViewById(R.id.editText3);
}
public void intCache(View view){
File fileDir=getCacheDir();
File myFile=new File(fileDir,"User_info_intCache.txt");
write(myFile);
}
public void extCache(View view){
File fileDir=getExternalCacheDir();
File myFile=new File(fileDir,"User_info_extCache.txt");
write(myFile);
}
public void pvtDir(View view){
File fileDir=getExternalFilesDir("User_Info");
File myFile=new File(fileDir,"User_info_pvtExt.txt");
write(myFile);
}
public void pubDir(View view){
File fileDir= Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS);
File myFile=new File(fileDir,"User_info_pubExt.txt");
write(myFile);
}
private void write(File myFile){
String unameS=uname.getText().toString();
String pwdS=pwd.getText().toString();
FileOutputStream fileOutputStream=null;
try {
fileOutputStream=new FileOutputStream(myFile);
try {
fileOutputStream.write(unameS.getBytes());
fileOutputStream.write(pwdS.getBytes());
} catch (IOException e) {
e.printStackTrace();
}
} catch (FileNotFoundException e) {
e.printStackTrace();
}
finally {
try {
if (fileOutputStream != null) {
fileOutputStream.close();
}
Toast.makeText(this,"data is written to "+myFile.getAbsolutePath(),Toast.LENGTH_LONG).show();
} catch (IOException e) {
e.printStackTrace();
}
}
}
I can see the files user_info_extCache.txt , User_info_pvtExt.txt. I know that internal cache location ( User_info_intCache.txt ) cant be seen.But i can't find the User_info_pubExt.txt file which must be stored in public directory Downloads.I cant see the file created by following code.
File fileDir= Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS);
File myFile=new File(fileDir,"User_info_pubExt.txt");
The toast shows that the file is created by above piece of code under /storage/emulated/0/Download/User_info_pubExt.txt .
I find somewhere that if phone is connected to pc,external storage cant be accessed.So i tried both by removing the mobile from pc.The toast says that file is created.But i cant find it under that folder.
AndroidManifest.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.iamka.storage">
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>
<application
android:allowBackup="true"
android:icon="#mipmap/ic_launcher"
android:label="#string/app_name"
android:roundIcon="#mipmap/ic_launcher_round"
android:supportsRtl="true"
android:theme="#style/AppTheme">
<activity android:name=".MainActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity android:name=".Main2Activity"></activity>
</application>

Your toast claiming that data is written is on the wrong place. As the toast also displays when there is an exception.
Place the toast in the try block instead. Or yet better after the close() but only if you close().
And place other toasts in the catch blocks to inform the user with e.getMessage().
As for the exception: all the paths exept the last one do not need any read/write permission at all. For the latter you need read/write permission.
But requesting them in manifest is not enough for Android 6+ as then you have to add some code to ask the user to confirm the requested permissions.
Google for runtime permissions.

FileNotFoundException(permission) when trying to write string from web to file

i am trying to build an application that downloads files (e.g. ".jpg", ".txt") from the web when given a url. its not really meant to be a real world application, more just an exercise to help me become more comfortable with network and io based code. for now i am just pulling the bytes from the url and then converting them to a string and logging that. then from there i want to write this to a file. the problem i am running into now is that im getting a file not found exception stating that access is denied:
07-11 21:03:14.458 19072-20051/com.example.zacharymcdaniel.webdownloader E/AsyncDownload: network errorjava.io.FileNotFoundException: /sdcard/-1157023572 (Permission denied)
java.io.FileNotFoundException: /sdcard/-1157023572 (Permission denied)
at java.io.FileOutputStream.open(Native Method)
at java.io.FileOutputStream.<init>(FileOutputStream.java:221)
at java.io.FileOutputStream.<init>(FileOutputStream.java:169)
at com.example.zacharymcdaniel.webdownloader.AsyncDownload.doInBackground(AsyncDownload.java:60)
at com.example.zacharymcdaniel.webdownloader.AsyncDownload.doInBackground(AsyncDownload.java:23)
at android.os.AsyncTask$2.call(AsyncTask.java:304)
at java.util.concurrent.FutureTask.run(FutureTask.java:237)
at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:243)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1133)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:607)
at java.lang.Thread.run(Thread.java:761)
here is my manifest:
<?xml version="1.0" encoding="utf-8"?>
<uses-permission android:name="android.permission.INTERNET"/>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
<application
android:allowBackup="true"
android:icon="#mipmap/ic_launcher"
android:label="#string/app_name"
android:roundIcon="#mipmap/ic_launcher_round"
android:supportsRtl="true"
android:theme="#style/AppTheme">
<activity android:name=".MainActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
and the code for the asynctask implementation i am using to perform the download and write operation:
public class AsyncDownload extends AsyncTask<Void, Void, Void>{
private static final String TAG = "AsyncDownload";
private static final String STORAGE_LOCATION = "/sdcard/"; //android directory picker is needed
private URL url;
private ArrayList<Byte> bytes = new ArrayList<>();
public AsyncDownload(URL url){
this.url = url;
}
#Override
protected Void doInBackground(Void... params){
try{
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
BufferedReader in = new BufferedReader(new InputStreamReader(connection.getInputStream()));
ByteArrayOutputStream buffer = new ByteArrayOutputStream();
int c;
while ((c = in.read()) != -1){
buffer.write(c);
}
Log.i(TAG, buffer.toString());
Random rand = new Random(4L);
String temp = String.valueOf(rand.nextInt());
String finalLocation = STORAGE_LOCATION + temp;
File file = new File(finalLocation);
file.getParentFile().mkdirs();
file.setWritable(true);
file.setReadable(true);
FileOutputStream fOut = new FileOutputStream(file);
fOut.write(buffer.toByteArray());
fOut.flush();
fOut.close();
FileInputStream fIn = new FileInputStream(finalLocation);
String reRead = new String();
int a;
while ((a = fIn.read()) != -1){
reRead += a;
}
Log.i(TAG, reRead);
//this section is for automatic file naming
/*Random rand = new Random(5L);
String fileNumber = String.valueOf(rand.nextInt());
StringBuilder sb = new StringBuilder();
sb.append(fileNumber).append("download"); //definitely needs work
Log.i(TAG, sb.toString());*/
//FileOutputStream fOut = new FileOutputStream()
}catch (IOException ioe){
Log.e(TAG, "network error" + ioe.toString(), ioe);
}
return null;
}
}
i am pretty new to this so i may have made some pretty obvious mistakes. please help solve this error. thank you.

add this to your activity
if (ContextCompat.checkSelfPermission(context,
android.Manifest.permission.WRITE_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {
ActivityCompat.requestPermissions(InterviewListActivity.this,
new String[]{android.Manifest.permission.WRITE_EXTERNAL_STORAGE}, REQUEST_CODE_EXT_STORAGE);
}

call this method in your activity
protected void checkPermissions() {
final int writeExternalPermissionCheck = ActivityCompat.checkSelfPermission(this, Manifest.permission.WRITE_EXTERNAL_STORAGE);
if (writeExternalPermissionCheck != PackageManager.PERMISSION_GRANTED {
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE},
Constant.REQUEST_CODE_ASK_PERMISSIONS);
}
}
}
and override this method
#Override
public void onRequestPermissionsResult(int requestCode, #NonNull String[] permissions, #NonNull int[] grantResults) {
switch (requestCode) {
case Constant.REQUEST_CODE_ASK_PERMISSIONS:
if (grantResults!=null) {
if (grantResults[0] == PackageManager.PERMISSION_GRANTED) {
//Call ur save method here or change the variable value true
} else {
Logger.toast(this, "Please enable write permission from Apps);
}
}
break;
default:
super.onRequestPermissionsResult(requestCode, permissions, grantResults);
}
}
Hope This helps.

Api level 6.0 or above you need runtime permission