это код в моем приложении, надеюсь, эта помощь
запись
File path = new File(Environment.getExternalStorageDirectory(),"/text");
if (!path.exists()){path.mkdirs();}
try{
File text = new File(path,"text.txt");
FileWriter writer = new FileWriter(text);
writer.append(edit.getText());
writer.flush();
writer.close();
}
catch////
чтение
File txt = new File(Environment.getExternalStorageDirectory(),"/text");
File file = new File(txt,"text.txt");
StringBuilder text = new StringBuilder();
if(file.exists()) {
try {
BufferedReader br = new BufferedReader(new FileReader(file));
String line;
while ((line = br.readLine()) != null) {
text.append(line);
text.append('\n');
tv.setText(Text);
}
//catch