Using different method depending on class in Java

I'm trying to reduce some code duplication. Currently i got two methods that are almost identical, the major difference being calling two separate methods within them.

Below is basically what i wanna do:

private void combinedMethod(SomeClass sc, Class c)
{
    Method m = null;
    if(c instanceof SubClass1)
        m = sc.Method();
    if(c instanceof SubClass2)
        m = sc.AnotherMethod();

    m(c.getA(), c.getB());
}

I've tested (and it works) this using reflection. But is there a better way of doing it? I read somewhere that reflection is slow and only to be used as a last resort. Is it in this case?

Also in this case the SomeClass is a standard class in the java api. The Class I send in is of my own making.