attachInterrupt question

In my first AttachInterrupt attempt I found the same problem. Brushing my two bits of hookup wire together [my 'switch'] produced anything up to 5 interrupts. My not-so-sophisticated debounce routine consisted of ignoring any interrupt within a second of the previous one. My needs were simple so this sufficed.

//globals.
long lastint = 0; //when last interrupt occurred.
...
void int0_isr()
{
  if(abs(millis() - lastint) < 1000)//less than a sec since last int.
  {
    lastint = millis();
    return;
  }
  Serial.println("int0 called");
  lastint = millis();
...