Iterating over and deleting from Hashtable in Java

java iterator hashtable
Mohit BAnsal picture Mohit BAnsal · Feb 28, 2010 · Viewed 114.2k times · Source

I have a Hashtable in Java and want to iterate over all the values in the table and delete a particular key-value pair while iterating.

How may this be done?

Answer

Adamski picture Adamski · Feb 28, 2010

You need to use an explicit java.util.Iterator to iterate over the Map's entry set rather than being able to use the enhanced For-loop syntax available in Java 6. The following example iterates over a Map of Integer, String pairs, removing any entry whose Integer key is null or equals 0.

Map<Integer, String> map = ...

Iterator<Map.Entry<Integer, String>> it = map.entrySet().iterator();

while (it.hasNext()) {
  Map.Entry<Integer, String> entry = it.next();

  // Remove entry if key is null or equals 0.
  if (entry.getKey() == null || entry.getKey() == 0) {
    it.remove();
  }
}

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