Using the system default setting to open a file : Desktop « Development « Java Tutorial

1. Java Tutorial
2. Development
3. Desktop

import java.awt.Desktop;
import java.io.File;
import java.io.IOException;

public class Test {
  public static void main(String[] a) {
    try {
      Desktop desktop = null;
      if (Desktop.isDesktopSupported()) {
        desktop = Desktop.getDesktop();
      }

       desktop.open(new File("c:\\a.txt"));
    } catch (IOException ioe) {
      ioe.printStackTrace();
    }

  }
}