//兩條線段是否相交，{(0,0),(2,2)} {(2,0),(1.9,1.8)}
        boolean res = Line2D.linesIntersect(0,0,2,2,2,0,1.9,1.8);
        System.out.println(res);

        //點是否在多邊形內，{(0,0),(2,0),(2,2),(0,2),(0,0)} 測試點(1,1)
        GeneralPath path = new GeneralPath();
        //設定多邊形起始點
        path.moveTo(0,0);

        path.lineTo
 
(2,0);
        path.lineTo(2,2);
        path.lineTo(0,2);
        //影象完成，封閉
        path.lineTo(0,0);

        //多邊形結束
        path.closePath();
        System.out.println(path.contains(1,1));