题目：
1、定义GeometricObject类，要求如下：

1) 3个私有实例变量，分别是字符串类型的color，布尔类型的filled，Date类型的createdDate

2) 2个构造方法：一个无参，一个带参

3) 实例变量color和filled的访问器和修改器

4) 实例变量createdDate的修改器

5) 重写父类的toString、equals和hashCode方法

2、定义Triangle的类继承自GeometricObject，要求如下：

1) 三个名为side1，side2和side3的double类型私有数据域，初始值均为1.0

2) 2个构造方法

3) side1，side2和side3的访问器和修改器

4) getArea()的方法返回三角形的面积

5) getPerimeter()的方法返回三角形的周长

6) 重写父类的toString、equals和hashCode方法（按照教材给定的规范写）

3、定义Cricle的类继承自GeometricObject，要求如下：

1）1个名为radius的double类型私有数据域，初始值均为1.0

2）2个构造方法

3）radius的访问器和修改器

4）getArea()的方法返回圆的面积

5）getPerimeter()的方法返回圆的周长

6）重写父类的toString、equals和hashCode方法（按照教材给定的规范写）

package text;
import java.util.Date;

class GeometricObject
{
    private String color;
    private boolean filled;
     Date createdDate;
   

     public GeometricObject(String color,boolean filled,Date createdDate)
{
    this.color=color;
    this.filled=filled;
    this.createdDate=createdDate;
}
     public GeometricObject(){}

     public String getColor() {
         return color;
}

     public void setColor(String co) {
         color =co;
}

     public boolean isFilled() {
         return filled;
}

     public void setFilled(boolean fill) {
         filled = fill;
}

     public Date getCreatedDate() {
         return createdDate;
}

     public String toString() {
         return "Created on " + createdDate + "\ncolor " + color +
            " and filled" + filled;
}
}


class Triangle extends GeometricObject
{
     private double side1, side2, side3;    

     public Triangle(String color,boolean filled,double side1, double side2, double side3){
         setColor(color);
         setFilled(filled);
         this.side1=side1;
         this.side2=side2;
         this.side3=side3; 

  }
     public double getSide1() {
         return side1;
}
     public void setSide1(double s1) {
         side1 =s1;
}
     public double getSide2() {
         return side2;
}
     public void setSide2(double s2) {
         side2 =s2;
}
     public double getSide3() {
         return side3;
}
     public void setSide3(double s3) {
         side3 =s3;
}
     public Object setArea()
     {
         return getArea();
     }
     public double getArea()
     {
         return ((side2+side3-side1)/2*(side1+side3-side2)/2*(side1+side2-side3)/2);
     }
     public Object setPerimeter()
     {
         return getPerimeter();
     }
     public double getPerimeter()
     {
         return side1+side2+side3;
     }
     public void printTriangle() {
         System.out.println(getCreatedDate());
     }
     public String toString() {
        return "Triangle"+side1+getArea()+getPerimeter();
}
}


class Circle extends GeometricObject
{
    private double radius;
    public Circle(String color,boolean filled,double radius)
    {
         setColor(color);
         setFilled(filled);
         this.radius=radius;       

    }
    public Circle(){}

    public double getRadius()

    {
         return radius;
    }
     public void setRadius(double rad)
     {
        radius =rad;
     }
     public Object setArea()
     {
         return getArea();
     }
     public double getArea()
     {
         return radius*radius*Math.PI;
     }
     public double getPerimeter()
     {
         return 2*radius*Math.PI;
     }
     public void printCircle()
     {
         System.out.println(getCreatedDate());
     }
      public String toString() {
            return "Circle"+getArea()+getPerimeter();
    }
}
   

public class main {
    Public static double getArea(GeometricObject[] obj){
        return

    }
    public static void main(String[] args) {
    GeometricObject trigle = new Triangle("red",true,3,4,5);
    System.out.println(trigle.getCreatedDate());
    System.out.println(trigle.isFilled());
    System.out.println(((Triangle) trigle).getSide1());
    System.out.println(((Triangle) trigle).getArea());
    System.out.println(((Triangle) trigle).getPerimeter());
   

    GeometricObject circle = new Circle("blue",false,12.34);
    System.out.println(circle.getCreatedDate());
    System.out.println(circle.isFilled());
    System.out.println(circle.getColor());
    System.out.println(((Circle) circle).getRadius());
    System.out.println(((Circle) circle).getArea());
    System.out.println(((Circle) circle).getPerimeter());
   

   

    GeometricObject[] objArray = new GeometricObject[5];
    objArray[0] = new Circle("blue",false,1.1);
    objArray[1] = new Circle("yellow",true,2.1);
    objArray[2] = new Circle("green",false,3.1);
   

    objArray[3] = new Triangle("green",false,3.1,3.1,3.1);
    objArray[4] = new Triangle("pink",true,5.1,4.1,8.1);

   

    System.out.println(getArea(objArray));
    }

   

}