this is manifest file :
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
...
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<application
android:requestLegacyExternalStorage="true"
android:allowBackup="true"
...
</manifest>
i used tedpermission. Text file named by date (ex:2020_10_23.txt) from external storage(ex:storage/emulated/0/myDiary/2020_10_23.txt) for i/o operation.
here core code in mainactivity :
PermissionListener permissionlistener = new PermissionListener() {
@Override
public void onPermissionGranted() {
Toast.makeText(MainActivity.this, "Permission granted", Toast.LENGTH_SHORT).show();
}
@Override
public void onPermissionDenied(List<String> deniedPermissions) {
Toast.makeText(MainActivity.this, "Permission denied\n" + deniedPermissions.toString(), Toast.LENGTH_SHORT).show();
}
};
@RequiresApi(api = Build.VERSION_CODES.R)
@Override
public void onCreate(Bundle savedInstanceState) {
TedPermission.with(this)
.setPermissionListener(permissionlistener)
.setDeniedMessage("External Storage READ/WRITE Denied")
.setPermissions(Manifest.permission.WRITE_EXTERNAL_STORAGE, Manifest.permission.READ_EXTERNAL_STORAGE)
.check();
...
final String sdPath = Environment.getExternalStorageDirectory().getAbsolutePath();
final File myDir = new File(sdPath + "/myDiary");
string fileName = Integer.toString(year) + "_"
+ Integer.toString(monthOfYear + 1) + "_"
+ Integer.toString(dayOfMonth) + ".txt";
...
btnWrite.setOnClickListener(new View.OnClickListener() {
@RequiresApi(api = Build.VERSION_CODES.O)
public void onClick(View v) {
try {
//openFileoutput Methods does not allow path delimiters.
File current_file = new File(myDir + "/" + fileName);
if (!current_file.getParentFile().exists()) {
if (!current_file.getParentFile().mkdirs()) {
Toast.makeText(getApplicationContext(),
"Failed to create folder : " + myDir, Toast.LENGTH_SHORT).show();
}
}
if (!current_file.exists()) {
if (!current_file.createNewFile()) {
Toast.makeText(getApplicationContext(),
"Failed to create file : " + myDir + "/" + fileName, Toast.LENGTH_SHORT).show();
}
}
FileOutputStream outFs = new FileOutputStream(new File(String.valueOf(current_file)));
String str = edtDiary.getText().toString();
outFs.write(str.getBytes());
outFs.close();
Toast.makeText(getApplicationContext(),
fileName + " is saved", Toast.LENGTH_SHORT).show();
} catch (IOException e) {
Toast.makeText(getApplicationContext(),
"Failed to save file : " + myDir + "/" + fileName, Toast.LENGTH_SHORT).show();
e.printStackTrace();
}
}
});
...
//read text file from external storage
String readDiary(String fName) {
String diaryStr = null;
FileInputStream inFs;
try {
inFs = new FileInputStream(new File(fName));
byte[] txt = new byte[500];
inFs.read(txt);
inFs.close();
diaryStr = (new String(txt)).trim();
btnWrite.setText("modify");
} catch (IOException e) {
edtDiary.setHint("no existing diary");
btnWrite.setText("new save");
}
return diaryStr;
}
Android version: 11
App permissions :
and this is logcat:
2020-10-23 15:40:00.986 6178-6178/com.cookandroid.project8_1 W/System.err: java.io.IOException: No such file or directory
2020-10-23 15:40:00.986 6178-6178/com.cookandroid.project8_1 W/System.err: at java.io.UnixFileSystem.createFileExclusively0(Native Method)
2020-10-23 15:40:00.986 6178-6178/com.cookandroid.project8_1 W/System.err: at java.io.UnixFileSystem.createFileExclusively(UnixFileSystem.java:317)
2020-10-23 15:40:00.986 6178-6178/com.cookandroid.project8_1 W/System.err: at java.io.File.createNewFile(File.java:1008)
2020-10-23 15:40:00.986 6178-6178/com.cookandroid.project8_1 W/System.err: at com.cookandroid.project8_1.MainActivity$3.onClick(MainActivity.java:102)
2020-10-23 15:40:00.987 6178-6178/com.cookandroid.project8_1 W/System.err: at android.view.View.performClick(View.java:7448)
2020-10-23 15:40:00.987 6178-6178/com.cookandroid.project8_1 W/System.err: at android.view.View.performClickInternal(View.java:7425)
2020-10-23 15:40:00.987 6178-6178/com.cookandroid.project8_1 W/System.err: at android.view.View.access$3600(View.java:810)
2020-10-23 15:40:00.987 6178-6178/com.cookandroid.project8_1 W/System.err: at android.view.View$PerformClick.run(View.java:28305)
2020-10-23 15:40:00.987 6178-6178/com.cookandroid.project8_1 W/System.err: at android.os.Handler.handleCallback(Handler.java:938)
2020-10-23 15:40:00.987 6178-6178/com.cookandroid.project8_1 W/System.err: at android.os.Handler.dispatchMessage(Handler.java:99)
2020-10-23 15:40:00.987 6178-6178/com.cookandroid.project8_1 W/System.err: at android.os.Looper.loop(Looper.java:223)
2020-10-23 15:40:00.987 6178-6178/com.cookandroid.project8_1 W/System.err: at android.app.ActivityThread.main(ActivityThread.java:7656)
2020-10-23 15:40:00.987 6178-6178/com.cookandroid.project8_1 W/System.err: at java.lang.reflect.Method.invoke(Native Method)
2020-10-23 15:40:00.987 6178-6178/com.cookandroid.project8_1 W/System.err: at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:592)
2020-10-23 15:40:00.987 6178-6178/com.cookandroid.project8_1 W/System.err: at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:947)
it cannot create folder 'myDiary' on storage/emulated/0 I tried everything I could. why cannot create folder,file even i given external storage I/O Permissions?
On Android 11 you have no access to the root of external storage.
You cannot create files or folders in /storage/emulated/0.
But.. you can write to the usual public folders on /storage/emulated/0 like
Download, Documents, DCIM, Pictures, Alarms, a.s.o.
Look which folders there are already on your device and you can mostly use them for read and or write operations.