Iterating over and deleting from Hashtable in Java

Question

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 1

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();   } }