Android creates files to implement the example of listening to files

public class FileObserverTest extends Activity{
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
MyFileObserver mfo = new MyFileObserver(getApplicationContext().getFilesDir() + "/data.txt");
mfo.startWatching();// Start file listening 
//mfo.stopWatching();// Cancel file listening 
}
public class MyFileObserver extends FileObserver {
public MyFileObserver(String path) {
    super(path);
}
@Override
public void onEvent(int event, String path) {
    switch (event) {
    case android.os.FileObserver.CREATE:
        //  The file is created 
        Log.d("FileObserver", "---file create---");
        break;
    case android.os.FileObserver.OPEN:
        //  The file is opened 
        //Log.d("FileObserver", "---file open---");
        break;
    case android.os.FileObserver.ACCESS:
        //  After opening the file, read the file content operation 
        //Log.d("FileObserver", "---file access---");
        break;
    case android.os.FileObserver.MODIFY:
        // The file is modified 
        Log.d("FileObserver", "---file MODIFY---");
        break;
    }
}
}
}