计算多边形面积

1.多边形计算面积模型

2.代码

public class Point{  
    public int x;  
    public int y;  
    Point(){  
        this.x=0;  
        this.y=0;  
    }
    public int getX() {
        return x;
    }
    public int getY() {
        return y;
    }
    public void setX(int x) {
        this.x = x;
    }
    public void setY(int y) {
        this.y = y;
    }  
    
} 

import java.util.ArrayList;
import java.util.List;

public class CaculateArea {  
    public static float CalculateArea(List<Point> vectorPoints)
    {
        int i, iCount;
        i = 0;
        float iArea = 0;
        iCount = vectorPoints.size();

        for (i = 0; i < iCount; i++)
        {
            iArea = iArea + (vectorPoints.get(i).getX() * vectorPoints.get((i + 1) % iCount).getY() - vectorPoints.get((i + 1) % iCount).getX() * vectorPoints.get(i).getY());
        }

        return (float)Math.abs(0.5 * iArea);
    }
    
    public static void main(String args[])   
    {  
        List<Point> vectorPoints = new ArrayList<Point>();
        Point p1 = new Point();
        p1.setX(1);
        p1.setY(1);
        Point p2 = new Point();
        p2.setX(0);
        p2.setY(2);
        Point p3 = new Point();
        p3.setX(3);
        p3.setY(3);
        Point p4 = new Point();
        p4.setX(4);
        p4.setY(1);
        vectorPoints.add(p1);
        vectorPoints.add(p2);
        vectorPoints.add(p3);
        vectorPoints.add(p4);
        System.out.println("多边形面积是："+CalculateArea(vectorPoints));  
    }  
}  

3 运行结果

多边形面积是：5.0