Most efficient way to prevent an infinite recursion in toString()?

Question

To string on a collection can get into a infinite loop if somewhere in the graph of collected items is a reference back to itself. See example below.

Yes, good cod

Answer 1

If you want to go overboard, you could use an aspect that tracks nested collections whenever you call toString().

public aspect ToStringTracker() {
  Stack collections = new Stack();

  around( java.util.Collection c ): call(String java.util.Collection+.toString()) && target(c) {
    if (collections.contains(c)) { return "recursion"; }
    else { 
      collections.push(c);
      String r = c.toString(); 
      collections.pop();
      return r;
    }
  }
}

I'm never 100% on syntax without throwing this into Eclipse, but I think you get the idea