By default, any files that you save to Internal Storage are private to your application. They cannot be accessed by other applications, nor the user under normal circumstances. These files are deleted when the user uninstalls the application.
To Write Text to a File
String fileName= "helloworld";
String textToWrite = "Hello, World!";
FileOutputStream fileOutputStream;
try {
fileOutputStream = openFileOutput(fileName, Context.MODE_PRIVATE);
fileOutputStream.write(textToWrite.getBytes());
fileOutputStream.close();
} catch (Exception e) {
e.printStackTrace();
}
To Append Text to an Existing File
Use Context.MODE_APPEND
for the mode parameter of openFileOutput
fileOutputStream = openFileOutput(fileName, Context.MODE_APPEND);