import java.io.File; import java.io.IOException; import java.io.PrintWriter; public class MyWriter { public static void main(String[] args) { System.out.println("Starting..."); String fileName = "numbers.txt"; try (PrintWriter writer = new PrintWriter(new File(fileName))) { int sep = 1; for (int i = 0; i < 10; i++) { sep++; writer.print(i); if (sep == 3) { writer.write("\n"); sep = 1; } } } catch (final IOException ex) { ex.printStackTrace(); } } }