public class Main {

  public static void main(String[] args) {

    double myNumber = 123456.78;

    String result;

​

    // Default

    result = String.format("%f", myNumber);

    System.out.println(result);

​

    // Two decimal digits

    result = String.format("%.2f", myNumber);

    System.out.println(result);

​

    // No decimal digits

    result = String.format("%.0f", myNumber);

    System.out.println(result);

​

    // No decimal digits but keep the decimal point

    result = String.format("%#.0f", myNumber);

    System.out.println(result);

​

    // Group digits

    result = String.format("%,.2f", myNumber);

    System.out.println(result);

​

    // Scientific notation with two digits of precision

    result = String.format("%.2e", myNumber);

    System.out.println(result);

  }

}

​