circle.java

包含了形形色色的c基本程序。

// Fig. 27.3: Circle.java
// Definition of class Circle

public class Circle extends Point {  // inherits from Point
   protected double radius;

   // No-argument constructor
   public Circle()
   {
      // implicit call to superclass constructor occurs here
      setRadius( 0 );  
   } // end Circle constructor

   // Constructor
   public Circle( double r, int a, int b )
   {
      super( a, b );  // call to superclass constructor
      setRadius( r );  
   } // end Circle constructor

   // Set radius of Circle
   public void setRadius( double r ) 
      { radius = ( r >= 0.0 ? r : 0.0 ); }

   // Get radius of Circle
   public double getRadius() { return radius; }

   // Calculate area of Circle
   public double area() { return Math.PI * radius * radius; }

   // convert the Circle to a String
   public String toString()
   {
      return "Center = " + "[" + x + ", " + y + "]" +
             "; Radius = " + radius;
   } // end method toString
} // end class Circle


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