import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;

public class Main {
  public static void main(String[] args) throws IOException {
    BufferedWriter bw = new BufferedWriter(new FileWriter("filename.txt"));
    bw.write("First line");
    bw.newLine();
    bw.write("Second line");
    bw.close();
    BufferedReader br = new BufferedReader(new FileReader("filename.txt"));
    System.out.println(br.readLine());
    System.out.println(br.readLine());
    br.close();
  }
}