program9_5.java

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

public class Elevator
{
  // class variable declaration section
  private int currentFloor;
  private static final int MAXFLOOR = 15;
  
  // class method definition section
  public Elevator()  // this is the default constructor
  {
    currentFloor = 1;
  }
  public Elevator(int cfloor)  // an overloaded constructor
  {
    currentFloor = cfloor;
  }
  void request(int newfloor)
  {
    if (newfloor < 1 || newfloor > MAXFLOOR || newfloor == currentFloor)
      ;  // do nothing
    else if ( newfloor > currentFloor)  // move elevator up
    {
      System.out.println("\nStarting at floor " + currentFloor);
      while (newfloor > currentFloor)
      {
        currentFloor++;    // add one to current floor
        System.out.println("   Going Up - now at floor " + currentFloor);
      }
      System.out.println("Stopping at floor " + currentFloor);
    }
    else  // move elevator down
    {
      System.out.println("\nStarting at floor " + currentFloor);      
      while (newfloor < currentFloor)
      {
        currentFloor--;   // subtract one from current floor
        System.out.println("   Going Down - now at floor " + currentFloor);
      }
      System.out.println("Stopping at floor " + currentFloor);
    }
  }
      
  public static void main(String[] args)
  {
    Elevator a = new Elevator();   // declare 1 object of type Elevator
    
    a.request(6);
    a.request(3);
  }
}