point.java

Java2入门经典第五章源码

class Point
{
  // Coordinates of the point
  double x;
  double y;

  // Create a point from coordinates
  Point(double xVal, double yVal)
  {
    x = xVal;
    y = yVal;
  }

  // Create a point from another Point object
  Point(final Point oldPoint)
  {
    x = oldPoint.x;    // Copy x coordinate
    y = oldPoint.y;    // Copy y coordinate
  }

  // Move a point
  void move(double xDelta, double yDelta)
  {
    // Parameter values are increments to the current coordinates
    x += xDelta;
    y += yDelta;
  }

  // Calculate the distance to another point
  double distance(final Point aPoint)
  {
    return Math.sqrt( 
       (x - aPoint.x)*(x - aPoint.x) + (y - aPoint.y)*(y - aPoint.y) );
  }

  // Convert a point to a string 
  public String toString()
  {
    return Double.toString(x) + ", " + y;    // As "x, y"
  }
}