falltime.java

《A first book of java》by Gary J.Bronson 北大出版社

import java.text.*; // needed for formatting
public class FallTime
{
  public static void main(String[] args)
  {
    int height;  
    double time;
    DecimalFormat df = new DecimalFormat("#.00");
    height = 800;
    time = Math.sqrt(2 * height / 32.2);
    System.out.println("It will take " + df.format(time)
              + " seconds to fall " + height + " feet.");
  }
}