Java programming examples: Hashmap

Java programming examples: Hashmap

1. public class HashMapJavaTricky{
2.  
3. public static void main(String[] args) {
4.  
5.     HashMap<Integer,String> hm= new HashMap<Integer, String>();  
6. 
   
7.      hm.put(1, "one");
8.      hm.put(2, "two");
9.      hm.put(3, "three");
10.  
11.      hm.put(1, "ONE");
12.      hm.put(null,null);
13.  
14.     System.out.println(hm.size()); 
15.  
16. for (Integer name: hm.keySet()){
17.  
18.    System.out.println(name + " " + hm.get(name)); 
19.   
20. }
21.  
22. }
23. }

 

1. 4
2. null null
3. 1 ONE
4. 2 two
5. 3 three