LinkedHashMap

 It maintain the order of elements according to the order in which keys weer inserted into map.
 Inserted Order is not affected if a key is re-inserted int the map.
 Key Duplication is not allowed


package collection.demos;



import java.util.LinkedHashMap;



public class LinkedHashMapDemo {

    public static void main(String[] args) {

        LinkedHashMap<String,String> abbreviations=new LinkedHashMap<String,String>();

        abbreviations.put("DB", "Data Base");

        abbreviations.put("Sys", "System");

        abbreviations.put("SRS", "Software Requirements Specification");

        System.out.println("Elements : "+abbreviations);

        abbreviations.put("Sys","Systems");//same output will be

        System.out.println("Elements : "+abbreviations);

        System.out.println("Elements of key Sys : "+abbreviations.get("Sys"));

    }

}