List and Map in java programing - list

Question

I need to convert:
List<Map>([{1,2},{2,3}])
To:
List<List>([[1,2],[2,3]])
Can anyone help me with example for this ...
Thanks

Answer 1

I would suggest making a list of specific objects instead of a raw list that the get(0) returns the key and get(1) the value as follows:
List<List<Pair>> convert(List<Map<Integer,Integer> mapList){
List<List<Pair>> listOfList = new ArrayList<List<Pair>>();
for(Map<Integer,Integer> map:mapList){
List<Pair> list = new ArrayList<Pair>();
for(Entry<Integer,Integer> e:map.entrySet()){
list.add(Pair(e.getKey(),e.getValue());
}
listOfList.add(list);
}
return listOfList;
}
class Pair{
Integer first;
Integer second;
//constructor
}

Answer 2

You can try the following Code:
import java.util.*;
class ListOfMapToListOfList
{
public static List<List> toList(List<Map<Integer,Integer>> lList)//method to convert List<Map> to List<List>
{
List<List> list = new ArrayList<List>();
for (int i = 0 ; i < lList.size() ; i++)
{
Map<Integer,Integer> map = lList.get(i);
List<Integer> aList = new ArrayList<Integer>();
Set<Integer> keySet = map.keySet();
for (Integer key : keySet)
{
aList.add(key);
aList.add(map.get(key));
}
list.add(aList);
}
return list;
}
public static void main(String[] args) //main body
{
List<Map<Integer,Integer>> list1 = new ArrayList<Map<Integer,Integer>>();
Map<Integer,Integer> map1 = new HashMap<Integer,Integer>();
map1.put(1,2);
Map<Integer,Integer> map2 = new HashMap<Integer,Integer>();
map2.put(1,2);
list1.add(map1);list1.add(map2);
System.out.println(list1);
System.out.println(toList(list1));//Conversion is done here..and out put is shown.
}
}