Question

I am trying to create a generic container (e.g. java code below), which has some restrictions, e.g items bigger than some limit cannot be put in it. Problem is that since T is an unknown type, the comparison function with an integer is reporting an error. How to fix this problem?

Secondly, is there a solution if the code was written in C++?

public class Box<T> {
    private T val;
    private int max;

    public Box (int m, T initval) { max = m; val = initval; }

    public T get() { return val; }
    public void set(T newval) {
        val = newval;
        if(newval.toInt() >= max)    // error on toInt
             System.out.printf("ERR: size too big\n");
        }
}

Answer 1

You should have

interface ToIntable {
  int toInt();
}

and

public class Box<T extends ToIntable> {
...
    if (newval.toInt() >= max) doSomething();
...
}