// define FileWriter instance (parameter true: Its mean append the message to log-file.)
FileWriter fileWriter = new FileWriter(path,true);
// define BufferedWriter instance
BufferedWriter bufferedWriter = new BufferedWriter(fileWriter);
bufferedWriter.write(message); // write message to log-file.
bufferedWriter.newLine(); // write new line to log-file.
bufferedWriter.close(); // close the BufferedWriter instance.
fileWriter.close(); // close the FileWriter stream