Clever Geek Handbook

What is LinkedHashMap and what is it used for?

When I was going through the sample code with ListViews I came up with LinkedHashMap

. What is LinkedHashMap

and where can we use it and how? I have looked through several articles but did not fully understand. This is required when creating ListView

. What is the relationship between ListViews and LinkedHashMaps? Thank.

+3


source to share


4 answers


For simplicity, let's figure out what is the difference between HashMap and LinkedHashMap .

HashMap : it gives the result in random orders, means there is no correct sequence for how we inserted the values.

then

LinkedHashMap . It gives the result in sequential order.



Let's look at a small example: with HashMap

    // suppose we have written a program
    .
    .
    // now use HashMap
    HashMap map = new HashMap();  // create object
    map.put(1,"Rohit");          // insert values
    map.put(2,"Rahul");
    map.put(3,"Ajay");

    System.out.println("MAP=" +map); //print the output using concatenation


    //So the output may be in any order like we can say the output may be as:
    Map={3=Ajay,2=Rahul,1=Rohit}

but this is not the case in LinkedHashMap Just replace "HashMap" with "LinkedHashMap" in the above code and see it displays the output in sequential order, eg 1 = Rohit will be displayed first and then the rest.

+2


source


The docs are here. But it's basically a HashMap that also has a linked list, so you can have a sequentially ordered iteration through it. Note that this means deletion can be O (n) time because you need to delete it from both data structures.



+2


source


LinkedHashMap - hashmap. But it maintains the insertion order. But HashMap doesn't maintain order.

+1


source


Hi Linked Hash Map is a map that stores a pair of key values, A Linked Hash Map adds values ​​which can be very slow but very easy when retrieving the values. For quick retrieval of values, we may prefer Linked Hash Map.

+1


source






More articles:


All Articles