Iterator over HashMap in Java

Question

I tried to iterate over hashmap in Java, which should be a fairly easy thing to do. However, the following code gives me some problems:

HashMap hm = new HashMap(         


        

Answer 1

1. Using EntrySet() and for each loop

      for(Map.Entry entry: hashMap.entrySet()) {
        System.out.println("Key Of map = "+ entry.getKey() + 
                         " , value of map = " + entry.getValue() );
    }
   

2. Using keyset() and for each loop

            for(String key : hashMap.keySet()) {
               System.out.println("Key Of map = "+ key + " , 
                         value of map = " + hashMap.get(key) );
              }
   

3. Using EntrySet() and java Iterator

         for(String key : hashMap.keySet()) {
           System.out.println("Key Of map = "+ key + " , 
                         value of map = " + hashMap.get(key) );
           }
   

4. Using keyset() and java Iterator

        Iterator keysIterator = keySet.iterator();
       while (keysIterator.hasNext()) {
           String key = keysIterator.next();
           System.out.println("Key Of map = "+ key + " , value of map = " + hashMap.get(key) );
      }
   

Reference : How to iterate over Map or HashMap in java