【每日日报】第十二天

1 今天写了以点类设计三角类：

题目要求：

 

 程序源代码：

 package Plane;

public class Point {
 double x;
    double y;
    Point()//无参构造
    {
      x=0;
      y=0;
         System.out.println("Point Constructor run");
 }
    Point(double xv,double yv)//有参构造
    {
   x=xv;
      y=yv;
      System.out.println("Point Constructor run");
  }
    Point(Point p)            //拷贝构造
    {
     x=p.x;
      y=p.y;
      System.out.println("Point CopyConstructor run");
    }
    void show()            //显示Point信息
    {
      System.out.print("("+x+","+y+")");
    }
   void setX(double xv){x=xv;}        //设置X坐标
   void setY(double yv){y=yv;}        //设置Y坐标
   double getX() {return x;}           //获取X坐标
   double getY() {return y;}           //获取Y坐标
}

 

package Plane;

public class Plane extends Point {
 Plane(){}
 Plane(double xv,double yv){super(xv,yv);}
 Plane(Plane p){super(p);}
   double length(){return 0;}
   double area(){return 0;}
}

 

package Plane;

public class Triangle extends Plane{

   Point a,b,c;
   Triangle()
   {
    a=new Point(0,0);
    b=new Point(0,0);
    c=new Point(0,0);
    System.out.println("Triangle Constructor run");
   }
   Triangle(Point aa,Point bb,Point cc)
   {
        a=aa;
        b=bb;
        c=cc;
           System.out.println("Triangle Constructor run");
      }
      Triangle(Triangle T)    //拷贝构造函数      
      {
          a=T.a;
          b=T.b;
          c=T.c;
          System.out.println("Triangle CopyConstructor run");
   }
    void setA(Point P)          //设置A顶点
   {
           a.setX(P.getX());
           a.setY(P.getY());
   }
    Point getA(){return a;}
    void setB(Point P)
    {
          b.setX(P.getX());
          b.setY(P.getY());
    }
    Point getB(){return b;}
    void setC(Point P)
    {
         c.setX(P.getX());
         c.setY(P.getY());
     }
    Point getC(){ return c; }
    void show()
    {
         System.out.print("Triangle(A=");
         a.show();
         System.out.print(",B=");
         b.show();
         System.out.print(",c=");
         c.show();
         System.out.print(")");
     }
     double area()
     {
           double S;
           Point p= new Point(a);
           double x1=p.getX();

           Point q= new Point(a);
           double y1=q.getY();
           Point m=new Point(b);
           double x2=m.getX();

           Point n=new Point(b);
           double y2=n.getY();
           Point Y=new Point(c);
           double x3=Y.getX();

           Point J=new Point(c);
           double y3=J.getY();
           double a1=Math.pow(((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2)),0.5);
           double b1=Math.pow(((x1-x3)*(x1-x3)+(y1-y3)*(y1-y3)),0.5);
           double c1=Math.pow(((x3-x2)*(x3-x2)+(y3-y2)*(y3-y2)),0.5);
           double p1=(a1+b1+c1)*0.5;
           S=Math.pow((p1*(p1-a1)*(p1-b1)*(p1-c1)),0.5);
           return S;
       }
       double length()
       {
           double L;
           double x1=a.getX();
           Point o=new Point(a);
           double y1=o.getY();
           Point m=new Point(b);
           double x2=m.getX();
           Point p=new Point(b);
           double y2=p.getY();
           Point n=new Point(c);
           double x3=n.getX();
           Point q=new Point(c);
           double y3=q.getY();
           L=Math.pow(((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2)),0.5)+Math.pow(((x1-x3)*(x1-x3)+(y1-y3)*(y1-y3)),0.5)+Math.pow(((x3-x2)*(x3-x2)+(y3-y2)*(y3-y2)),0.5);
           return L;
       }
}

 

package Plane;

import java.util.Scanner;

public class Tma extends Triangle{
 void length(Triangle p){System.out.println("Length="+p.length());}
 void area(Triangle p){System.out.println("Area="+p.area());}
    public static void main(String[] args)
    {
     double x,y;
        Point p1=new Point();
        Point p2=new Point(1,1);
        Point p3=new Point(2,2);
        Triangle t1=new Triangle();
        Triangle t2=new Triangle(t1);
        t1.show();
        System.out.println();
        Tma t=new Tma();
        t.area(t1);
        t.length(t1);
        Scanner in=new Scanner(System.in);
        x=in.nextDouble();
        y=in.nextDouble();
        p1.setX(x);
        p1.setY(y);
        t2.setA(p1);
        t2.setB(p2);
        t2.setC(p3);
        t2.show();
        System.out.println();
        t.area(t2);
        t.length(t2);
        in.close();
    }

}

运行截图：

 

2 当子类有构造函数时，父类也要有构造函数

3 明天继续写题