exercise8_1.java

Introduction to java programming 一书中所有编程练习部分的源码

// Exercise8_1.java: Create a class Triangle that extends
// GeometricObject
class Triangle extends Object {
  double side1, side2, side3;

  /** Constructor */
  public Triangle(double side1, double side2, double side3) {
  }

  /** Implement the abstract method findArea in GeometricObject */
  public double findArea() {
    double s = (side1 + side2 + side3) / 2;
    return Math.sqrt(s * (s - side1) * (s - side2) * (s - side3));
  }

  /** Implement the abstract method findCircumference in
   * GeometricObject
   **/
  public double findPerimeter() {
    return side1 + side2 + side3;
  }
  
  /** Override the toString method */
  public String toString() {
    // Implement it to return the three sides
    return "Triangle: side1 = " + side1 + " side2 = " + side2 +
      " side3 = " + side3;
  }
}