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Calling remove in foreach loop in Java

Asked 2009-07-28T20:39:07.540
679

In Java, is it legal to call remove on a collection when iterating through the collection using a foreach loop? For instance:

List<String> names = ....
for (String name : names) {
   // Do something
   names.remove(name).
}

As an addendum, is it legal to remove items that have not been iterated over yet? For instance, 

//Assume that the names list as duplicate entries
List<String> names = ....
for (String name : names) {
    // Do something
    while (names.remove(name));
}
java loops iterator foreach
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2 Answers

96
for (String name : new ArrayList<String>(names)) {
    // Do something
    names.remove(nameToRemove);
}

You clone the list names and iterate through the clone while you remove from the original list. A bit cleaner than the top answer.

answered 2013-01-23T22:01:15.477
1
  1. Try this 2. and change the condition to "WINTER" and you will wonder:
public static void main(String[] args) {
  Season.add("Frühling");
  Season.add("Sommer");
  Season.add("Herbst");
  Season.add("WINTER");
  for (String s : Season) {
   if(!s.equals("Sommer")) {
    System.out.println(s);
    continue;
   }
   Season.remove("Frühling");
  }
 }
answered 2011-01-05T14:24:18.817

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