My app (Android API 15) makes a picture and stores it in the internal memory's folder. Now, I want to copy this file to another folder inside of the external storage, e.g. /sdcard/myapp
. I tried the following approaches:
Approach #1:
private void copyFile(File src, File dst) throws IOException {
File from = new File(src.getPath());
File to = new File(dst.getPath());
from.renameTo(to);
}
Approach #2:
private void copyFile(File src, File dst) throws IOException {
FileChannel inChannel = null;
FileChannel outChannel = null;
try {
inChannel = new FileInputStream(src).getChannel();
outChannel = new FileOutputStream(dst).getChannel();
} catch (FileNotFoundException e) {
e.printStackTrace();
}
try {
inChannel.transferTo(0, inChannel.size(), outChannel);
} finally {
if (inChannel != null)
inChannel.close();
if (outChannel != null)
outChannel.close();
}
}
Approach #3:
private void copyFile(File src, File dst) throws IOException {
FileInputStream inStream = new FileInputStream(src);
if (!dst.exists()) {
dst.mkdir();
}
if (!dst.canWrite()) {
System.out.print("CAN'T WRITE");
return;
}
FileOutputStream outStream = new FileOutputStream(dst);
FileChannel inChannel = inStream.getChannel();
FileChannel outChannel = outStream.getChannel();
inChannel.transferTo(0, inChannel.size(), outChannel);
inStream.close();
outStream.close();
}
None of these methods doesn't solve my task. In checked a number of related topics, and the only suggestion I found is to verify the persistence of
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
in AndroidManifest.xml
and it does persist.
The approach #1 finishes the execution, but no folder and files are copied.
In the approach #2, the app fails with the exception java.lang.NullPointerException
at outChannel = new FileOutputStream(dst).getChannel();
, but the object dst is not a null.
In the approach #3, I decided to verify if the destination object exists and it creates a folder if needed, but when I check if I can write, the check returns false
.
I tried a couple of additional approaches, which succeeded to create an empty folder, but no files are really copied.
Since this is my very first step towards Android, I feel I miss some small thing. Please, point me, how to copy a file from one folder to another folder in Android, including file moving from internal to external memory.
I solved my issue. The problem was in the destination path, in the original code:
File dst = new File(dstPath);
the variable dstPath
had the full destination path, including the name of the file, which is wrong. Here is the correct code fragment:
String dstPath = Environment.getExternalStorageDirectory() + File.separator + "myApp" + File.separator;
File dst = new File(dstPath);
exportFile(pictureFile, dst);
private File exportFile(File src, File dst) throws IOException {
//if folder does not exist
if (!dst.exists()) {
if (!dst.mkdir()) {
return null;
}
}
String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss").format(new Date());
File expFile = new File(dst.getPath() + File.separator + "IMG_" + timeStamp + ".jpg");
FileChannel inChannel = null;
FileChannel outChannel = null;
try {
inChannel = new FileInputStream(src).getChannel();
outChannel = new FileOutputStream(expFile).getChannel();
} catch (FileNotFoundException e) {
e.printStackTrace();
}
try {
inChannel.transferTo(0, inChannel.size(), outChannel);
} finally {
if (inChannel != null)
inChannel.close();
if (outChannel != null)
outChannel.close();
}
return expFile;
}
Thanks for the tips.