length.java

来自「Java程序设计技巧与开发实例附书源代码。」· Java 代码 · 共 56 行

package lengthtest;

public class Length
{
   private double value = 0;
   private String scale = "none";
   private boolean isValid = false;

   public Length(double _value, String _scale)
   {
      value = _value;
      scale = _scale;
      if ( (value >= 0) && ( (scale.equals("meter"))
                            || (scale.equals("feet"))))
      {
         isValid = true;
      }
   }

   public Length convertToFeet()
   {
      if ( (scale.equals("feet")) || (!isValid))
      {
         return this;
      }
      else
      {
         return new Length(value * 3.2809, "feet");
      }
   }

   public Length convertToMeter()
   {
      if ( (scale.equals("meter")) || (!isValid))
      {
         return this;
      }
      else
      {
         return new Length(value / 3.2809, "meter");
      }
   }

   public void showLength()
   {
      if (isValid)
      {
         System.out.println(value + " " + scale);
      }
      else
      {
         System.out.println("invalid length");
      }
   }
}