What to return as the minimum element of an empty heap

Question

I have written this simple code to check weather a binary heap is empty or not. I have problem with return. It can not be: null, void, or nothing; It should return something int, but I don't know what. So, what should I put there, if I want to keep this code simple? (I mean not using Integer class or java.lang.Integer).

public int getMinimum() {    
  if (isEmpty()) {
    System.out.println("Heap is empty"); 
    return;           
  } else
    return data[0];
}

Answer 1

throw a exception for invalid value and handle it when calling

public int getMinimum() throws Exception {
  if (isEmpty())
      throw new Exception("Heap is Empty");
  else
      return data[0];
}

and when getting minimum

 try{
    int i = getMinimum();
    System.out.println("Minimum is :" + i);
 }catch(Exception e){
    System.out.println(e.getMessage());
 }