HashMap class with generics

Mon Dec 28, 2009 7:58 pm

HashMap class with generics :
In this example . we see how we reverse the key and value .

Code:: import java.util.HashMap; import java.util.Map; public class TestHashMap { public static void main(String args[]) { TestHashMap hashMap = new TestHashMap(); HashMap<String,Integer> oldhashMap = new HashMap<String, Integer>(); oldhashMap.put("a",1); oldhashMap.put("2", 2); HashMap<Integer,String> map = hashMap.copyHashMap(oldhashMap); System.out.println("Value of key =1 is : "+map.get(1)); } public <V, K> HashMap<V, K> copyHashMap(HashMap<K,V> oldhashMap) { HashMap<V, K> newhashMap = new HashMap<V,K>(); for(Map.Entry<K, V> entry :oldhashMap.entrySet()) { newhashMap.put(entry.getValue(),entry.getKey()); } return newhashMap; } }

The output is :
Value of key =1 is : a