x={10,20,30...} y={20,40,60...} 
Polygon p = new Polygon(x, y, x.length); //创建多边形
if (p.contains(new Point(mouse.x, mouse.y))) { //判断多边形是否包含某个点
    System.out.println("contains");
}

------解决方案--------------------

Java code
    int[] x = new int[] {
        10, 10, 30, 40
    };
    int[] y = new int[] {
        10, 30, 60, 10
    };
    Polygon polygon = new Polygon(x, y, x.length);
    Point p = new Point(20, 25);
    System.out.println(polygon.contains(p));
    Point q = new Point(100, 100);
    System.out.println(polygon.contains(q));