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Reading and writing files on Internal storage

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rutura edited this page Apr 17, 2017 · 1 revision
  • Three locations where you can work with files:
    • Internal storage
    • External storage
    • Assets
  • For internal storage, android lets you call:
    FileOutputStream mOutput = Context.openFileOutput(FILENAME, Activity.MODE_PRIVATE);

to get a tream ou use to write to a file named FILENAME under the root of the app private internal storage space,and

    FileInputStream mInput = Context.openFileInput(FILENAME);

to get a stream you use to read from that same file

  • The second parameter to Context.openFileOutput() can either be MODE_PRIVATE : to override the file if it already is there or MODE_APPEND : to append the new content to the file if it already exists.
  • The rest would be normal java I/O stuff.One possible way to write is :
   try {
            FileOutputStream mOutput = openFileOutput(FILENAME, Activity.MODE_PRIVATE);
            String data = "THIS DATA WRITTEN TO A FILE";
            mOutput.write(data.getBytes());
            mOutput.close();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
}

and you would possibly read like this:

    try {
            FileInputStream mInput = openFileInput(FILENAME);
            byte[] data = new byte[128];
            mInput.read(data);
            mInput.close();

            String display = new String(data);
            tv.setText(display.trim());
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
}
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