[Belisarius]

As my professor explained it, if you do this:

void foo(){
  int a = 4;
  addSix(a);
}

void addSix(int input){
  input = input + 6;
}

"a" will still be 4 after calling addSix() from foo(). But if you do this:

void foo(){
  Hashtable ht = new Hashtable();
  addSomething(ht);
}

void addSomething(Hashtable input){
  input.put("foo","bar");
}

"ht" will contain "bar" with a key of "foo" after calling addSomething() from foo().