// different ways to iterate

// for loop
for (int i = 0; i < n; i++) {
  // do something with i
}

Set<String> names = new HashSet<String>();
// fill you names

//
Iterator<String> namesIt = names.iterator();
// hasNext
// next
// remove

while (namesIt.hasNext()) {
  // can remove
  // do something with namesIt.next()
}

// foreach loop, enhanced for loop
for (String name : names) {
  // can't remove
  // do something with name
}

Map<String, Integer> m;
// ...

for (String key : m.keySet()) {
}