How to remove a key from HashMap while iterating over it

Question

I am having HashMap called testMap which contains String  String   HashMap lt String  String gt  testMap   new HashMap lt String  String gt       When iterating the map  if value is match with specified string  I need to remove the key from map   i e   for Map Entry lt String  String gt  entry   testMap entrySet        if entry getValue   equalsIgnoreCase  Sample          testMap remove entry getKey             testMap contains  Sample  but I am unable to remove the key from HashMap  Instead getting error     Exception in thread  main  java util ConcurrentModificationException     at java util HashMap HashIterator nextEntry Unknown Source      at java util HashMap EntryIterator next Unknown Source      at java util HashMap EntryIterator next Unknown Source

User · Answer

Use Iterator remove

User · Answer

Try   Iterator lt Map Entry lt String String gt  gt  iter   testMap entrySet   iterator    while  iter hasNext          Map Entry lt String String gt  entry   iter next        if  Sample  equalsIgnoreCase entry getValue              iter remove              With Java 1 8 and onwards you can do the above in just one line   testMap entrySet   removeIf entry - gt   Sample  equalsIgnoreCase entry getValue

User · Answer

To remove specific key and element from hashmap use   hashmap remove key    full source code is like  import java util HashMap  public class RemoveMapping        public static void main String a             HashMap hashMap   new HashMap            hashMap put 1   One            hashMap put 2   Two            hashMap put 3   Three            System out println  Original HashMap     hashMap           hashMap remove 3              System out println  Changed HashMap     hashMap                     Source   http   www tutorialdata com examples java collection-framework hashmap remove-mapping-of-specified--key-from-hashmap

[java] How to remove a key from HashMap while iterating over it?

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