java - HashMap's Iterator to prevent concurrent modification -

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• iterating on , removing map 12 answers

the following piece of code, while executed single thread, throws concurrentmodificationexception on line 4:

map<string, string> map = new hashmap<string, string>(); map.put("key1", "value1"); map.put("key2", "value2"); (string key : map.keyset()) { // here     map.remove(key); } 

i couldn't find map.iterator() or map.mapiterator() method on hashmap javadoc. should do?

as guessed, need iterator removing items during iteration. way map iterate entryset() (or, alternatively, keyset(), if need evaluate key):

iterator<map.entry<string, string>> entryiter = map.entryset().iterator(); while (iter.hasnext()) {     map.entry<string, string> entry = iter.next();     iter.remove(); // guard condition? }