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import java.util.Collection;
import java.util.Iterator;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;
/** Copyright (c), AnkitMittal JavaMadeSoEasy.com */
public class ConcurrentHashMapIteratorExample {
public static void main(String args[]){
Map<Integer,String> concurrentHashMap=new ConcurrentHashMap<Integer,String>();
//maintains natural order of keys
concurrentHashMap.put(21, "javaMadeSoEasy");
concurrentHashMap.put(11, "ankit");
System.out.println("\n---1. Iterate on keys, by obtaining iterator on keySet---");
Iterator<Integer> keyIterator=concurrentHashMap.keySet().iterator();
while(keyIterator.hasNext()){
System.out.println(keyIterator.next());
}
System.out.println("\n---obtain keySet from Map---");
Set<Integer> keySet=concurrentHashMap.keySet();
System.out.println("---now iterate on keySet using enhanced for loop---");
for(Integer key :keySet){
System.out.println(key);
}
System.out.println("\n---2. Iterate on values, by obtaining iterator on values---");
Iterator<String> valueIterator=concurrentHashMap.values().iterator();
while(valueIterator.hasNext()){
System.out.println(valueIterator.next());
}
System.out.println("\n---obtain values from Map---");
Collection<String> collection=concurrentHashMap.values();
System.out.println("---now iterate on values using enhanced for loop---");
for(String value :collection){
System.out.println(value);
}
System.out.println("\n---3. Iterate on entry, by obtaining iterator on entrySet---");
Iterator<Entry<Integer, String>> entryIterator=concurrentHashMap.entrySet().iterator();
while(entryIterator.hasNext()){
System.out.println(entryIterator.next());
}
System.out.println("\n---obtain entrySet from Map---");
Set<Entry<Integer, String>> entrySet=concurrentHashMap.entrySet();
System.out.println("---now iterate on entrySet using enhanced for loop---");
for(Entry<Integer, String> entry:entrySet){
System.out.println(entry);
}
}
}
/*OUTPUT
---1. Iterate on keys, by obtaining iterator on keySet---
21
11
---obtain keySet from Map---
---now iterate on keySet using enhanced for loop---
21
11
---2. Iterate on values, by obtaining iterator on values---
javaMadeSoEasy
ankit
---obtain values from Map---
---now iterate on values using enhanced for loop---
javaMadeSoEasy
ankit
---3. Iterate on entry, by obtaining iterator on entrySet---
21=javaMadeSoEasy
11=ankit
---obtain entrySet from Map---
---now iterate on entrySet using enhanced for loop---
21=javaMadeSoEasy
11=ankit
*/
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Labels:
Core Java