Java map interface

Linkedhashmap maintains the order during insertion, and treemap sorts the elements based on the key. hashmap is very casual.

Example

Map<Integer, Integer> map= new LinkedHashMap<Integer,Integer>();map.put(5, 6);map.put(3, 3);map.put(8, 1);for( Entry<Integer, Integer> entry: map.entrySet() ){System.out.println(entry.getKey() + " " + entry.getValue() );}

Output

5 63 38 1

For treemap

Map<Integer, Integer> map= new TreeMap<Integer,Integer>();map.put(5, 6);map.put(3, 3);map.put(8, 1);for( Entry<Integer, Integer> entry: map.entrySet() ){System.out.println(entry.getKey() + " " + entry.getValue() );}

Output

3 35 68 1

For hashmap,

Map<Integer, Integer> map= new HashMap<Integer,Integer>();map.put(5, 6);map.put(3, 3);map.put(8, 1);for( Entry<Integer, Integer> entry: map.entrySet() ){System.out.println(entry.getKey() + " " + entry.getValue() );}

Output

3 35 68 1

The output here is the same as that of treemap because there are too few elements, just coincidence.