[Java] 座標の値から三角形の面積を求めよう!!!

import java.util.Scanner;
import java.awt.geom.Point2D;

class Test01{
    public static void main(String[] args){
        Point2D.Double a=new Point2D.Double();
        Point2D.Double b=new Point2D.Double();
        Point2D.Double c=new Point2D.Double();
        Scanner s=new Scanner(System.in);

        System.out.print("a.x: "); a.x=s.nextDouble();
        System.out.print("a.y: "); a.y=s.nextDouble();
        System.out.print("b.x: "); b.x=s.nextDouble();
        System.out.print("b.y: "); b.y=s.nextDouble();
        System.out.print("c.x: "); c.x=s.nextDouble();
        System.out.print("c.y: "); c.y=s.nextDouble();

        System.out.println("三角形の面積:"+triangleArea(a,b,c));
}

    public static double triangleArea(Point2D.Double a,Point2D.Double b,Point2D.Double c){
        return Math.abs((a.x-c.x)*(b.y-c.y)-(b.x-c.x)*(a.y-c.y))/2;
    }

}


/* 実行結果

a.x: 0
a.y: 0
b.x: 1
b.y: 0
c.x: 1
c.y: 1
三角形の面積:0.5

a.x: -1
a.y: 1
b.x: 0
b.y: 0
c.x: 1
c.y: 1
三角形の面積:1.0

*/