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

public class Main {
  public static void main(String[] args) throws IOException {
    FileWriter myWriter = new FileWriter("filename.txt");
    myWriter.write("Hello World");
    myWriter.close();
    FileReader myReader = new FileReader("filename.txt");
    while (myReader.ready()) {
      System.out.print((char) myReader.read());
    }
    myReader.close();
  }
}