Change key of last element Hashmap

Question

i want to put another string as the key of the lastEntry of the Hash map.

after check the value of the lastEntry and change it i couldnt use setKey or another func to change the key i want to change the lastEntry.

EditText name; // put that as the key
Map<String,Integer> Names = new HashMap<String,Integer>(10);
// .
// .
// .
name = (EditText) findViewById(R.id.namep);

my func that check the value of the lastEntry and change it:

boolean flagScore = false;
Entry<String, Integer> lastEntry = Names.lastEntry();
if(lastEntry.getValue() < score){
    lastEntry.setValue(score);
    flagScore = true;
}
if(flagScore){
    // put name.getText().toString as key
}

Hashmap ordering is undefined, your approach may lead to surprises. — Alex Salauyou, Apr 23 '15 at 22:05
`Map` doesn't have any order, try not to fall into the XY problem - tell us what you want to achieve - not how you're trying to achieve it. — Nir Alfasi, Apr 23 '15 at 22:06
so how i can check it i tried to lastEntry = Names.get(Names.size()-1) but i cant use it — Adi, Apr 23 '15 at 22:07
i want to get the last element of the Map and check if the value — Adi, Apr 23 '15 at 22:08
First you need to define ordering. Maybe list of custom objects containing name and score would be better? — Alex Salauyou, Apr 23 '15 at 22:10
@GangaNaidu what you mean model class can you show me some code define — Adi, Apr 23 '15 at 22:12
I believe you should start with oop and data structure basics or chose more simple language (php is a good candidate) — Alex Salauyou, Apr 23 '15 at 22:14
@Adi, please read this solution, http://stackoverflow.com/questions/3527216/accessing-the-last-entry-in-a-map, there it is clearly explained why you cannot get a last entry from a `Map`. Solution also explains what alternatives you can use. Hope it helps — Shrikant Havale, Apr 23 '15 at 22:38

score 0 · Answer 1 · edited Apr 23 '15 at 22:42

0

You can use Model class and ArrayList to achieve this. For example

Take a class like this

public class Demo {
  private String name; 
  private integer value;

  //create getters and setters for this variables. 
}

And in your class create array list like this.

private ArrayList<Demo> namesList  = new ArrayList<Demo>;

create object for model class Demo demo = new Demo;

demo.name = "";
demo.value = 1;

Then add model class to ArrayList like this namesList.add(demo);

now you can do what ever you want with ArrayList.

edited Apr 23 '15 at 22:42

Christian Abella

5,747
2
30
42

answered Apr 23 '15 at 22:19

gkondati

516
4
16

ok but when i got 10 elements in my arraylist and then i want to check agian the last value (your code, The Demo is one object how i can divide it to value and key?) – Adi Apr 23 '15 at 22:25
@Adi String name = demo.name; int v = demo.value; – Alex Salauyou Apr 23 '15 at 22:43
You can get last value like this nameList.get(nameList.size()-1).getName(); //take this is the key nameList.get(nameList.size()-1).getValue();//take this is the key – gkondati Apr 23 '15 at 22:44

score 0 · Answer 2 · edited Jun 08 '15 at 06:33

This can be implemented by using LinkedHashMap also written a small program, hope it will help.

public class HashMapIssue {
public static void main(String[] args) {
    Map<String,Integer> map=new LinkedHashMap<String, Integer>();
    map.put("Integer2", 1);
    map.put("Integer1", 2);
    map.put("Integer3", 3);
    map.put("Integer4", 4);
    map.put("Integer5", 5);
    System.out.println(map);

    Set  enteries = map.entrySet();
    Iterator it = enteries.iterator();
    String lastkey="";
    Entry entry;
    while(it.hasNext()){
        entry=(Entry) it.next();
        lastkey=(String) entry.getKey();
    }
map.remove(lastkey);
map.put("modifiedkey",0);   
System.out.println(map);                 
   }
}

Output is:

{Integer2=1, Integer1=2, Integer3=3, Integer4=4, Integer5=5}
{Integer2=1, Integer1=2, Integer3=3, Integer4=4, modifiedkey=0}

Change key of last element Hashmap

2 Answers2