How to write files to external public storage in Android so that they are visible from Windows?
My app should save files to a place where, when you connect your phone/tablet to a computer, you can see them through the system file explorer.
This is the way I implemented file writing:
protected String mDir = Environment.DIRECTORY_DOCUMENTS;
protected File mPath = Environment.getExternalStoragePublicDirectory(mDir);
protected void writeLogFile(String filename) {
File f = new File(mPath, filename + ".txt");
f.getParentFile().mkdirs();
try (BufferedWriter bw = new BufferedWriter(new FileWriter(f, false))) {
// Details omitted.
} catch (Exception e) {
e.printStackTrace();
return;
}
makeText("Wrote " + f.getAbsolutePath());
}
This is what I see when I connect my Sony Xperia Z4 tablet to Windows (notice missing documents folder):
This is the directory to which the file is written (using above implementation):
What is wrong with my implementation?
Solution 1:
What is wrong with my implementation?
MediaStore
has not discovered your newly-created files yet. What you see in Windows — and in many on-device "gallery" apps — is based on what MediaStore
has indexed.
Use MediaScannerConnection
and its scanFile()
method to tell MediaStore
about your file, once you have written out your data to disk:
public void scanFile(Context ctxt, File f, String mimeType) {
MediaScannerConnection
.scanFile(ctxt, new String[] {f.getAbsolutePath()},
new String[] {mimeType}, null);
}
or, in Kotlin:
fun scanFile(ctxt: Context, f: File, mimeType: String) {
MediaScannerConnection.scanFile(ctxt, arrayOf(f.getAbsolutePath()), arrayOf(mimeType), null)
}