public class Main {
// 给你个例子，仔细看看吧

    public static Object sum(Object obj1, Object obj2) {

        int inttmp1 = 0, inttmp2 = 0;
        double doubletmp1 = 0.0, doubletmp2 = 0.0;

        if (obj1 instanceof Integer)
            inttmp1 = (Integer) obj1;

        else if (obj1 instanceof Double)
            doubletmp1 = (Double) obj1;

        if (obj2 instanceof Integer)
            inttmp2 = (Integer) obj2;

        else if (obj2 instanceof Double)
            doubletmp2 = (Double) obj2;

        return doubletmp1 + doubletmp2 + inttmp1 + inttmp2;
    }

    public static void main(String[] args) {
        System.out.println(sum(1, 2));
        System.out.println(sum(1.0, 2.5));
        System.out.println(sum(1, 2.5));

    }
}