ConcurrentSkipListMap - Iterator on keySet, values and entrySet is fail-safe or fail-fast?
The iterators returned by the iterator() method of the collections returned by all three Map's “collection view methods" are fail-safe. Means any structural modification made to ConcurrentSkipListMap like adding or removing elements during Iteration won’t throw any Exception.
import java.util.Iterator;
import java.util.Map;
import java.util.Map.Entry;
import java.util.concurrent.ConcurrentSkipListMap;
/** Copyright (c), AnkitMittal JavaMadeSoEasy.com */
public class ConcurrentSkipListMapTest {
public static void main(String args[]){
Map<Integer,String> concurrentSkipListMap=new ConcurrentSkipListMap<Integer,String>();
concurrentSkipListMap.put(11, "ankit");
concurrentSkipListMap.put(21, "javaMadeSoEasy");
System.out.println("\n---1. Iterate on keys, by obtaining iterator on keySet---");
//fail-safe
Iterator<Integer> keyIterator=concurrentSkipListMap.keySet().iterator();
while(keyIterator.hasNext()){
concurrentSkipListMap.put(4,"newEle4");
System.out.println(keyIterator.next());
}
System.out.println("\n---2. Iterate on values, by obtaining iterator on values---");
//fail-safe
Iterator<String> valueIterator=concurrentSkipListMap.values().iterator();
while(valueIterator.hasNext()){
concurrentSkipListMap.put(5,"newEle5");
System.out.println(valueIterator.next());
}
System.out.println("\n---3. Iterate on entry, by obtaining iterator on entrySet---");
//fail-safe
Iterator<Entry<Integer, String>> entryIterator=concurrentSkipListMap.entrySet().iterator();
while(entryIterator.hasNext()){
concurrentSkipListMap.put(6,"newEle6");
System.out.println(entryIterator.next());
}
}
}
/*OUTPUT
---1. Iterate on keys, by obtaining iterator on keySet---
11
21
---2. Iterate on values, by obtaining iterator on values---
newEle4
newEle5
ankit
javaMadeSoEasy
---3. Iterate on entry, by obtaining iterator on entrySet---
4=newEle4
5=newEle5
6=newEle6
11=ankit
21=javaMadeSoEasy
*/
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Collection programs
Core Java