How to pass to method TreeSet or HashMap and show it?

Question

I have such method:

public void show(Object o)
{
   //show content of object
}

and I would like to pass to it TreeSet or HashMap. But its a different iteration, I mean, when I want to show a content of TreeSet, I use that code:

 while ( iter.hasNext() )
    {
      System.out.println( iter.next());
    }

but when I have a HasMap, I print it like this:

Iterator iterator = map.keySet().iterator();  

while (iterator.hasNext()) {  
   String key = iterator.next().toString();  
   String value = map.get(key).toString();  

   System.out.println(key + " " + value);  
} 

Is there a way to show the content of a collection, when I dont know, if user pass a TreeSet or HashMap? I cant do any conversion in show method (thats not the point). Any ideas?

Answer 1

Not directly, but if your method is declared as:

public <T> void show(Iterable<T> iterable) {
  for(T t: iterable) {
    System.out.println(t);
  }
}

then you can use it like this:

show(set);
show(map.entrySet());

Not exactly what you want, but Map and Set are inherently different and you can't really treat them the same way (polymorphically).