butImportPatient.setOnClickListener(new View.OnClickListener() {

    @Override
    public void onClick(View view) {
         Intent intent = new Intent();
         intent.setAction(Intent.ACTION_OPEN_DOCUMENT);
         intent.setType("*/*");
         startActivityForResult(intent, IMPORTPATIENT_ACTIVITY_REQUEST_CODE);
    }
});

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {

      if (requestCode == IMPORTPATIENT_ACTIVITY_REQUEST_CODE && resultCode == RESULT_OK) {
            File file = new File(data.getData().getPath()) ;
            String path = file.getAbsolutePath() ;
            StringBuilder text = new StringBuilder();

            try {
                BufferedReader br = new BufferedReader(new FileReader(path));
                String line;

                while ((line = br.readLine()) != null) {
                    text.append(line);
                    text.append("n");

                }
                br.close();
            } catch (IOException e) {
                e.printStackTrace();
            }

            AlertDialog.Builder builder = new AlertDialog.Builder(this) ;
            builder.setMessage(path)
                    .show() ;

        }
 }

/document/home:List.txt