java通过设计两个类的构造方法(传递参数，并计算周长)，调用不同构造方法和面积函数来计算三角形和四边形

// 三角形类
public class Triangle {
     
     // 高
     private int hight;
     // 底    
      private int floor;
 
      // 边长A
      private int sideLengthA;
      // 边长B
      private int sideLengthB;
      // 边长C
      private int sideLengthC;
     
      // 周长
      private int perimeter;
 
      // 构造函数
     public Triangle (int hight,int floor,int sideLengthA,int sideLengthB,int sideLengthC) {
         this.hight = hight;
         this.floor = floor;
         this.sideLengthA = sideLengthA;
         this.sideLengthB = sideLengthB;
         this.sideLengthC = sideLengthC;
         this.perimeter = sideLengthA+sideLengthB+sideLengthC;
       }
 
       public  Triangle () {
       }
 
 
      // 获取周长
      public int getPerimeter () {
       return this.perimeter;
      }
 
     // 计算面积
      public int getArea () {
       return hight*floor;
      }
 
 
}
 
 
public class TestMain {
 
     public static void main(String args[]) {
    
         Triangle triangle = new Triangle(12,20,10,20,25);
         System.out.println("三角形的面积是："+triangle.getArea());
         System.out.println("三角形的周长是："+triangle.getPerimeter());
      }
 
}