Develop Reference

Android app, http request to ip address fails

I have simple "gadget" based on Arduino. It is connected to the wlan of my house and sending web requests to it turns on/off a red LED indicating that I'm busy/free in my room. This works fine when called from a browser or from my small winforms application. It is called synchronous, it is just enough, no need for async calls.
But, I tried to create a android app that sends the same requests, no success. I have read many topics, tried different ways etc. The app has this row in manifest file:
android:networkSecurityConfig="#xml/network_security_config"
Maybe something is still missing. This might be very very basic, but I haven't been able to get it working. Code:
public void onViewCreated(#NonNull View view, Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
binding.buttonFirst.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
OkHttpClient client = new OkHttpClient();
String url = "http://192.168.100.12/LED=ON";
Request req = new Request.Builder()
.url(url)
.build();
try {
client.newCall(req).execute();
} catch (IOException | RuntimeException e) {
e.printStackTrace();
}
NavHostFragment.findNavController(FirstFragment.this)
.navigate(R.id.action_FirstFragment_to_SecondFragment);
}
});
}
It fails on execute call. The app enters the catch section, but there's no understandable description in e. And of course, my mobile phone is connected to the same wlan.
Stack trace:
I/System.out: port:80
W/System.err: android.os.NetworkOnMainThreadException
W/System.err: at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1513)
W/System.err: at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:389)
W/System.err: at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:230)
W/System.err: at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:212)
W/System.err: at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:436)
W/System.err: at java.net.Socket.connect(Socket.java:631)
W/System.err: at okhttp3.internal.platform.AndroidPlatform.connectSocket(AndroidPlatform.kt:63)
W/System.err: at okhttp3.internal.connection.RealConnection.connectSocket(RealConnection.kt:295)
W/System.err: at okhttp3.internal.connection.RealConnection.connect(RealConnection.kt:207)
W/System.err: at okhttp3.internal.connection.ExchangeFinder.findConnection(ExchangeFinder.kt:226)
W/System.err: at okhttp3.internal.connection.ExchangeFinder.findHealthyConnection(ExchangeFinder.kt:106)
W/System.err: at okhttp3.internal.connection.ExchangeFinder.find(ExchangeFinder.kt:74)
W/System.err: at okhttp3.internal.connection.RealCall.initExchange$okhttp(RealCall.kt:255)
W/System.err: at okhttp3.internal.connection.ConnectInterceptor.intercept(ConnectInterceptor.kt:32)
W/System.err: at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.kt:109)
W/System.err: at okhttp3.internal.cache.CacheInterceptor.intercept(CacheInterceptor.kt:95)
W/System.err: at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.kt:109)
W/System.err: at okhttp3.internal.http.BridgeInterceptor.intercept(BridgeInterceptor.kt:83)
W/System.err: at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.kt:109)
W/System.err: at okhttp3.internal.http.RetryAndFollowUpInterceptor.intercept(RetryAndFollowUpInterceptor.kt:76)
W/System.err: at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.kt:109)
W/System.err: at okhttp3.internal.connection.RealCall.getResponseWithInterceptorChain$okhttp(RealCall.kt:201)
W/System.err: at okhttp3.internal.connection.RealCall.execute(RealCall.kt:154)
W/System.err: at com.example.donotdisturb.FirstFragment$1.onClick(FirstFragment.java:52)
W/System.err: at android.view.View.performClick(View.java:6603)
W/System.err: at com.google.android.material.button.MaterialButton.performClick(MaterialButton.java:1119)
W/System.err: at android.view.View.performClickInternal(View.java:6576)
W/System.err: at android.view.View.access$3100(View.java:780)
W/System.err: at android.view.View$PerformClick.run(View.java:26088)
W/System.err: at android.os.Handler.handleCallback(Handler.java:873)
W/System.err: at android.os.Handler.dispatchMessage(Handler.java:99)
W/System.err: at android.os.Looper.loop(Looper.java:193)
W/System.err: at android.app.ActivityThread.main(ActivityThread.java:6705)
W/System.err: at java.lang.reflect.Method.invoke(Native Method)
W/System.err: at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
W/System.err: at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:911)

Android Studio - java.io.FileNotFoundException: /abc.csv open failed: EACCES (Permission denied)

I am trying to read a CSV file, load its content to a spinner. I have given relevant permissions MANAGE_EXTERNAL_STORAGE, WRITE_EXTERNAL_STORAGE and READ_EXTERNAL_STORAGE to read a file from external storage. I have placed the CSV file in a directory requested permission on runtime. Also the file.exists() function return true but still unable to read csv file. Where am I going wrong?
Here is the error log:
022-02-27 18:03:32.457 13080-13080/com.example.locationfetcher_v2 W/System.err: java.io.FileNotFoundException: /storage/emulated/0/Khidmah/input.csv: open failed: EACCES (Permission denied)
2022-02-27 18:03:32.461 13080-13080/com.example.locationfetcher_v2 W/System.err: at libcore.io.IoBridge.open(IoBridge.java:492)
2022-02-27 18:03:32.461 13080-13080/com.example.locationfetcher_v2 W/System.err: at java.io.FileInputStream.<init>(FileInputStream.java:160)
2022-02-27 18:03:32.461 13080-13080/com.example.locationfetcher_v2 W/System.err: at java.io.FileInputStream.<init>(FileInputStream.java:115)
2022-02-27 18:03:32.461 13080-13080/com.example.locationfetcher_v2 W/System.err: at java.io.FileReader.<init>(FileReader.java:58)
2022-02-27 18:03:32.461 13080-13080/com.example.locationfetcher_v2 W/System.err: at com.example.locationfetcher_v2.MainActivity.onCreate(MainActivity.java:157)
2022-02-27 18:03:32.461 13080-13080/com.example.locationfetcher_v2 W/System.err: at android.app.Activity.performCreate(Activity.java:8157)
2022-02-27 18:03:32.461 13080-13080/com.example.locationfetcher_v2 W/System.err: at android.app.Activity.performCreate(Activity.java:8129)
2022-02-27 18:03:32.461 13080-13080/com.example.locationfetcher_v2 W/System.err: at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1310)
2022-02-27 18:03:32.461 13080-13080/com.example.locationfetcher_v2 W/System.err: at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3494)
2022-02-27 18:03:32.461 13080-13080/com.example.locationfetcher_v2 W/System.err: at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3693)
2022-02-27 18:03:32.461 13080-13080/com.example.locationfetcher_v2 W/System.err: at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:85)
2022-02-27 18:03:32.461 13080-13080/com.example.locationfetcher_v2 W/System.err: at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
2022-02-27 18:03:32.461 13080-13080/com.example.locationfetcher_v2 W/System.err: at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
2022-02-27 18:03:32.461 13080-13080/com.example.locationfetcher_v2 W/System.err: at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2135)
2022-02-27 18:03:32.461 13080-13080/com.example.locationfetcher_v2 W/System.err: at android.os.Handler.dispatchMessage(Handler.java:106)
2022-02-27 18:03:32.462 13080-13080/com.example.locationfetcher_v2 W/System.err: at android.os.Looper.loop(Looper.java:236)
2022-02-27 18:03:32.462 13080-13080/com.example.locationfetcher_v2 W/System.err: at android.app.ActivityThread.main(ActivityThread.java:8059)
2022-02-27 18:03:32.462 13080-13080/com.example.locationfetcher_v2 W/System.err: at java.lang.reflect.Method.invoke(Native Method)
2022-02-27 18:03:32.462 13080-13080/com.example.locationfetcher_v2 W/System.err: at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:656)
2022-02-27 18:03:32.462 13080-13080/com.example.locationfetcher_v2 W/System.err: at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:967)
2022-02-27 18:03:32.462 13080-13080/com.example.locationfetcher_v2 W/System.err: Caused by: android.system.ErrnoException: open failed: EACCES (Permission denied)
2022-02-27 18:03:32.462 13080-13080/com.example.locationfetcher_v2 W/System.err: at libcore.io.Linux.open(Native Method)
2022-02-27 18:03:32.462 13080-13080/com.example.locationfetcher_v2 W/System.err: at libcore.io.ForwardingOs.open(ForwardingOs.java:166)
2022-02-27 18:03:32.462 13080-13080/com.example.locationfetcher_v2 W/System.err: at libcore.io.BlockGuardOs.open(BlockGuardOs.java:254)
2022-02-27 18:03:32.462 13080-13080/com.example.locationfetcher_v2 W/System.err: at libcore.io.ForwardingOs.open(ForwardingOs.java:166)
2022-02-27 18:03:32.462 13080-13080/com.example.locationfetcher_v2 W/System.err: at android.app.ActivityThread$AndroidOs.open(ActivityThread.java:7932)
2022-02-27 18:03:32.462 13080-13080/com.example.locationfetcher_v2 W/System.err: at libcore.io.IoBridge.open(IoBridge.java:478)
2022-02-27 18:03:32.462 13080-13080/com.example.locationfetcher_v2 W/System.err: ... 19 more
Below is my code:
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//Using Dexter Library
Dexter.withContext(this)
.withPermissions(
Manifest.permission.MANAGE_EXTERNAL_STORAGE,
Manifest.permission.WRITE_EXTERNAL_STORAGE,
Manifest.permission.READ_EXTERNAL_STORAGE,
Manifest.permission.ACCESS_COARSE_LOCATION,
Manifest.permission.ACCESS_FINE_LOCATION,
Manifest.permission.CAMERA
).withListener(new MultiplePermissionsListener() {
#Override public void onPermissionsChecked(MultiplePermissionsReport report) {/* ... */}
#Override public void onPermissionRationaleShouldBeShown(List<PermissionRequest> permissions, PermissionToken token) {/* ... */}
}).check();
MultiplePermissionsListener dialogMultiplePermissionsListener =
DialogOnAnyDeniedMultiplePermissionsListener.Builder
.withContext(this)
.withTitle("Camera, Storage and Location permission")
.withMessage("All Camera, Storage and Location permission are required for this application")
.withButtonText(android.R.string.ok)
.build();
//// Read data from CSV file
List<String> addresses = new ArrayList<String>();
Spinner address_spinner = findViewById(R.id.spinnerAddress);
// File file = new File(Environment.getExternalStorageDirectory() + "/Khidmah/", "input.csv");
File file = new File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS), "input.csv");
show_notification(file.getPath());
show_notification(new Boolean(file.exists()).toString());
FileInputStream fis = null;
try {
if (file.exists()){
show_notification("can read - " + new Boolean(file.canRead()).toString());
CSVReader reader = new CSVReader(new FileReader(file.toURI().toString()));
show_notification("successfully read file...");
String[] nextLine;
while ((nextLine = reader.readNext()) != null) {
// nextLine[] is an array of values from the line
// System.out.println(nextLine[0] + nextLine[1] + nextLine[2]);
addresses.add(nextLine[0] + nextLine[1] + nextLine[2]);
show_notification(nextLine[0] + nextLine[1] + nextLine[2]);
}
ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, R.layout.support_simple_spinner_dropdown_item,addresses);
address_spinner.setAdapter(adapter);
}
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} catch (CsvValidationException e) {
e.printStackTrace();
}
}
Here is AndroidManifest.xml:
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.locationfetcher_v2">
<!-- Always include this permission -->
<uses-permission android:name="android.permission.MANAGE_EXTERNAL_STORAGE"/>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
<!-- Include only if your app benefits from precise location access. -->
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-permission android:name="android.permission.CAMERA" />
<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/Theme.LocationFetcher_v2"
android:foregroundServiceType="location">
<activity
android:name=".MainActivity"
android:exported="true">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<meta-data
android:name="preloaded_fonts"
android:resource="#array/preloaded_fonts" />
</application>
</manifest>
UPDATE
I am now using Dexter Library to grant permissions. I have added additional permission MANAGE_EXTERNAL_STORAGE and place the input.csv file in Public Directory i.e. Downloads folder. However now it's giving following error:
open failed: ENOENT (No such file or directory)

After File.exists() use File.canRead() before you act on the file.
This csv file is not created by your app.
Hence on Android 11 you are not the owner and although your app can check if the file exists it discovers with File.canRead() that the file is not accessable.
With MANAGE_EXTERNAL_STORAGE and the right runtime code your app can obtain access.
The right code would start an intent for Settings.ACTION_MANAGE_APP_ALL_FILES_ACCESS_PERMISSION.

how to connect android studio to mysql with jdbc

I've downloaded mysql-java-connector-5.1
and import it as library
the program is being compiled but no matter what i'm doing an exception is being thrown about connection failure.
i want to send data from the app(android studio-java) to sql data base which is stored in amazon(aws) and i want to get the data with raspberry pi(with c++).
the c++ works perfect.
with the android studio i canot connect, no to local host(mysql workbench) and not to aws.
i saw few templates on the web for the "url" parameter int the "getConnection" function, i used those:
for local host:
String url = "jdbc:mysql://<local ip>:<port>/<schema>
for aws:
String url = "jdbc:mysql://<endpoint given by aws>:<port>/<schema>
none of them work please help
this is my code:
public void test(View view) {
Connection conn = null;
try {
Class.forName("com.mysql.jdbc.Driver").newInstance();
} catch (InstantiationException e) {
e.printStackTrace();
} catch (IllegalAccessException e) {
e.printStackTrace();
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
try {
String url = "jdbc:mysql://192.168.1.17:3306/sys";
String user = "root";
String password = "password";
//local verion - find ip with ifconfig/what is my ip website
conn = DriverManager.getConnection(url, user, password);
// Do something with the Connection
} catch (SQLException ex) {
// handle any errors
Log.i("SQLException: " , ex.getMessage());
Log.i("SQLState: " , ex.getSQLState());
}
but conn always null.
did i forget something?
* by the way im not sure if i have to use the
Class.forName("com.mysql.jdbc.Driver").newInstance();
but i used it anyway.
this is the printStackTrace results:
System.err: com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Could not create connection to database server.
08-10 19:26:58.223 20891-20891/com.example.asaf.sql W/System.err: at java.lang.reflect.Constructor.newInstance0(Native Method)
08-10 19:26:58.225 20891-20891/com.example.asaf.sql W/System.err: at java.lang.reflect.Constructor.newInstance(Constructor.java:430)
08-10 19:26:58.227 20891-20891/com.example.asaf.sql W/System.err: at com.mysql.jdbc.Util.handleNewInstance(Util.java:425)
08-10 19:26:58.228 20891-20891/com.example.asaf.sql W/System.err: at com.mysql.jdbc.Util.getInstance(Util.java:408)
08-10 19:26:58.230 20891-20891/com.example.asaf.sql W/System.err: at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:919)
08-10 19:26:58.232 20891-20891/com.example.asaf.sql W/System.err: at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:898)
08-10 19:26:58.234 20891-20891/com.example.asaf.sql W/System.err: at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:887)
08-10 19:26:58.235 20891-20891/com.example.asaf.sql W/System.err: at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:861)
08-10 19:26:58.238 20891-20891/com.example.asaf.sql W/System.err: at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2267)
08-10 19:26:58.240 20891-20891/com.example.asaf.sql W/System.err: at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2016)
08-10 19:26:58.241 20891-20891/com.example.asaf.sql W/System.err: at com.mysql.jdbc.ConnectionImpl.(ConnectionImpl.java:776)
08-10 19:26:58.243 20891-20891/com.example.asaf.sql W/System.err: at com.mysql.jdbc.JDBC4Connection.(JDBC4Connection.java:47)
08-10 19:26:58.244 20891-20891/com.example.asaf.sql W/System.err: at java.lang.reflect.Constructor.newInstance0(Native Method)
08-10 19:26:58.245 20891-20891/com.example.asaf.sql W/System.err: at java.lang.reflect.Constructor.newInstance(Constructor.java:430)
08-10 19:26:58.247 20891-20891/com.example.asaf.sql W/System.err: at com.mysql.jdbc.Util.handleNewInstance(Util.java:425)
08-10 19:26:58.248 20891-20891/com.example.asaf.sql W/System.err: at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:386)
08-10 19:26:58.250 20891-20891/com.example.asaf.sql W/System.err: at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:330)
08-10 19:26:58.251 20891-20891/com.example.asaf.sql W/System.err: at java.sql.DriverManager.getConnection(DriverManager.java:569)
08-10 19:26:58.252 20891-20891/com.example.asaf.sql W/System.err: at java.sql.DriverManager.getConnection(DriverManager.java:219)
08-10 19:26:58.254 20891-20891/com.example.asaf.sql W/System.err: at com.example.asaf.sql.MainActivity.test(MainActivity.java:45)
08-10 19:26:58.255 20891-20891/com.example.asaf.sql W/System.err: at java.lang.reflect.Method.invoke(Native Method)
08-10 19:26:58.257 20891-20891/com.example.asaf.sql W/System.err: at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:288)
08-10 19:26:58.258 20891-20891/com.example.asaf.sql W/System.err: at android.view.View.performClick(View.java:5637)
08-10 19:26:58.259 20891-20891/com.example.asaf.sql W/System.err: at android.view.View$PerformClick.run(View.java:22429)
08-10 19:26:58.260 20891-20891/com.example.asaf.sql W/System.err: at android.os.Handler.handleCallback(Handler.java:751)
08-10 19:26:58.262 20891-20891/com.example.asaf.sql W/System.err: at android.os.Handler.dispatchMessage(Handler.java:95)
08-10 19:26:58.263 20891-20891/com.example.asaf.sql W/System.err: at android.os.Looper.loop(Looper.java:154)
08-10 19:26:58.265 20891-20891/com.example.asaf.sql W/System.err: at android.app.ActivityThread.main(ActivityThread.java:6119)
08-10 19:26:58.266 20891-20891/com.example.asaf.sql W/System.err: at java.lang.reflect.Method.invoke(Native Method)
08-10 19:26:58.267 20891-20891/com.example.asaf.sql W/System.err: at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886)
08-10 19:26:58.269 20891-20891/com.example.asaf.sql W/System.err: at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776)
08-10 19:26:58.272 20891-20891/com.example.asaf.sql W/System.err: Caused by: android.os.NetworkOnMainThreadException
08-10 19:26:58.273 20891-20891/com.example.asaf.sql W/System.err: at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1303)
08-10 19:26:58.273 20891-20891/com.example.asaf.sql W/System.err: at java.net.Inet6AddressImpl.lookupHostByName(Inet6AddressImpl.java:86)
08-10 19:26:58.274 20891-20891/com.example.asaf.sql W/System.err: at java.net.Inet6AddressImpl.lookupAllHostAddr(Inet6AddressImpl.java:74)
08-10 19:26:58.275 20891-20891/com.example.asaf.sql W/System.err: at java.net.InetAddress.getAllByName(InetAddress.java:752)
08-10 19:26:58.275 20891-20891/com.example.asaf.sql W/System.err: at com.mysql.jdbc.StandardSocketFactory.connect(StandardSocketFactory.java:188)
08-10 19:26:58.276 20891-20891/com.example.asaf.sql W/System.err: at com.mysql.jdbc.MysqlIO.(MysqlIO.java:301)
08-10 19:26:58.277 20891-20891/com.example.asaf.sql W/System.err: at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2188)
08-10 19:26:58.277 20891-20891/com.example.asaf.sql W/System.err: at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2221)

Here you have an example of a working method that connects to microsoft sql express
try {
StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
StrictMode.setThreadPolicy(policy);
connection = DriverManager.getConnection("jdbc:jtds:sqlserver://replacewithip:port//DBNAME", "User", "Password"); // Connect to database
if (connection == null) {
ConnectionResult = "Verify connection";
Toast.makeText(activity, ConnectionResult, Toast.LENGTH_LONG).show();
} else {
//do something with your connection, in this case I executed a query
ResultSet rs = null;
String query = "EXEC AppMovil.INITE_Articulos_Familia '" + codigo + "'";
Statement stmt = connection.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE, ResultSet.CONCUR_READ_ONLY);
//size = cantidad de rows, metodo para obtener cantidad de rows
rs = stmt.executeQuery(query);
ResultSetMetaData rsmtd = rs.getMetaData();
while(rs.next()){
ListaConsultaFamilia item = new ListaConsultaFamilia(
rs.getString("Codigo"),
rs.getString("Descripcion"),
rs.getString("Precio")
);
listaConsultaFamilias.add(item);
}
listaConsultaFamilias.size();
ConnectionResult = " successful";
isSuccess = true;
connection.close();
}
}catch (Exception ex)
{
//catch error while reading
Looper.prepare();
isSuccess = false;
Toast.makeText(activity, "No existen consultas en el periodo seleccionado", Toast.LENGTH_LONG).show();
ConnectionResult = ex.getMessage();
}

Android : error when copying asset sqlite database to database director

I want to use a pre fill database in my app so I found this code.
DB_NAME = "urg1718.sqlite"
public SQLiteDatabase openDatabase() {
File dbFile = context.getDatabasePath(DB_NAME);
String path = dbFile.getAbsolutePath();
Log.i("path", "openDatabase: " + path);
if (!dbFile.exists()) {
try {
//the file doesn't exist yet so this function is called
copyDatabase(dbFile);
} catch (IOException e) {
throw new RuntimeException("Error creating source database", e);
}
}
//check if the database is present in the folder
Log.i("database", "openDatabase: " + dbFile.exists());
return SQLiteDatabase.openDatabase(dbFile.getPath(), null, SQLiteDatabase.OPEN_READONLY);
}
private void copyDatabase(File dbFile) throws IOException {
//pre fil database
InputStream is = context.getAssets().open(DB_NAME);
try {
//where the error occurs
OutputStream os = new FileOutputStream(dbFile);
byte[] buffer = new byte[1024];
while (is.read(buffer) > 0) {
os.write(buffer);
}
os.flush();
os.close();
is.close();
} catch (FileNotFoundException e) {
e.printStackTrace();;
} catch (IOException e) {
e.printStackTrace();
}
}
The "OutputStream os = new FileOutputStream" catch the following error.
java.io.FileNotFoundException: /data/data/jle.urgdegarde17_18/databases/urg1718: open failed: ENOENT (No such file or directory)
W/System.err: at libcore.io.IoBridge.open(IoBridge.java:456)
W/System.err: at java.io.FileOutputStream.(FileOutputStream.java:87)
W/System.err: at java.io.FileOutputStream.(FileOutputStream.java:127)
W/System.err: at java.io.FileOutputStream.(FileOutputStream.java:116)
W/System.err: at jle.urgdegarde17_18.AssetDatabaseOpenHelper.copyDatabase(AssetDatabaseOpenHelper.java:49)
W/System.err: at jle.urgdegarde17_18.AssetDatabaseOpenHelper.openDatabase(AssetDatabaseOpenHelper.java:35)
W/System.err: at jle.urgdegarde17_18.Chargement.isStoragePermissionGranted(Chargement.java:40)
W/System.err: at jle.urgdegarde17_18.Chargement.onCreate(Chargement.java:18)
W/System.err: at android.app.Activity.performCreate(Activity.java:5990)
W/System.err: at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1106)
W/System.err: at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2278)
W/System.err: at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2387)
W/System.err: at android.app.ActivityThread.access$800(ActivityThread.java:151)
W/System.err: at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1303)
W/System.err: at android.os.Handler.dispatchMessage(Handler.java:102)
W/System.err: at android.os.Looper.loop(Looper.java:135)
W/System.err: at android.app.ActivityThread.main(ActivityThread.java:5254)
W/System.err: at java.lang.reflect.Method.invoke(Native Method)
W/System.err: at java.lang.reflect.Method.invoke(Method.java:372)
W/System.err: at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
W/System.err: at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)
W/System.err: Caused by: android.system.ErrnoException: open failed: ENOENT (No such file or directory)
W/System.err: at libcore.io.Posix.open(Native Method)
W/System.err: at libcore.io.BlockGuardOs.open(BlockGuardOs.java:186)
W/System.err: at libcore.io.IoBridge.open(IoBridge.java:442)
W/System.err: ... 20 more
I tried to use getDatabasePath(), getDatabasePath().getAbsolutePath() and directly put the string returned by those functions into FileOutputStream
I also tried to remove the ".sqlite" from the database name.
I don't understand what i'm doing wrong ...
Thank's.

Cannot create file in external storage

I'm trying to create a file in the external storage directory of the Nougat emulator. using the following code:
File file = new File(Environment.getExternalStorageDirectory().getAbsolutePath() + "/test987689");
if(!Environment.MEDIA_MOUNTED.equals(Environment.getExternalStorageState())){
Toast.makeText(this, "External SD card not mounted", Toast.LENGTH_LONG).show();
}try {
if (file.getParentFile().exists() || file.getParentFile().mkdirs()) {
file.createNewFile();
}
} catch (IOException e) {
e.printStackTrace();
}
Permissons:
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
And I'm getting the following error:
W/System.err: java.io.IOException: Permission denied
W/System.err: at java.io.UnixFileSystem.createFileExclusively0(Native Method)
W/System.err: at java.io.UnixFileSystem.createFileExclusively(UnixFileSystem.java:280)
W/System.err: at java.io.File.createNewFile(File.java:958)
W/System.err: at com.vibhinna.sreni.SplashActivity.onCreate(SplashActivity.java:41)
W/System.err: at android.app.Activity.performCreate(Activity.java:6658)
W/System.err: at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1118)
W/System.err: at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2584)
W/System.err: at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2692)
W/System.err: at android.app.ActivityThread.-wrap12(ActivityThread.java)
W/System.err: at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1445)
W/System.err: at android.os.Handler.dispatchMessage(Handler.java:102)
W/System.err: at android.os.Looper.loop(Looper.java:154)
W/System.err: at android.app.ActivityThread.main(ActivityThread.java:6044)
W/System.err: at java.lang.reflect.Method.invoke(Native Method)
W/System.err: at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:865)
W/System.err: at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:755)
What am I doing wrong?

If your targetSdk is 23 or higher, you should request permissions dynamically.
to know more : Requesting Permissions at Run Time

to get File path you can use Context.getExternalFilesDir()/Context.getExternalCacheDir()
for example
String path=Context.getExternalCacheDir()+"file.text";
File file=new File(path)
it doesnt need permission if the filepath is "Android/data/app package/file name"