cse-intro-genericsize.java

private static int genericSize(Object obj) {
    if (obj instanceof String) {
        String s = (String) obj;
        return s.length();
    } else if (obj instanceof int[]) {
        int[] a = (int[]) obj;
        return a.length;
    } else if (obj instanceof List) {
        List l = (List) obj;
        return l.size();
    } else if (obj instanceof ObjectWithSize) {
        ObjectWithSize o = (ObjectWithSize) obj;
        return o.count();
    } else {
        return -1;
    }
}