How to add List of objects in a Map

Question

I have a List and A is defined below.

How do i add in a Map with Key as Long and values as List of Strings.

Class A
{
Long in;
List<String> out;
}
Map<Long,List<String>>

`map.put(a.in, a.out);` https://docs.oracle.com/javase/7/docs/api/java/util/Map.html#put(K,%20V) — ortis, Nov 24 '14 at 15:02
possible duplicate of [Java: How to convert List to Map](http://stackoverflow.com/questions/4138364/java-how-to-convert-list-to-map) — Sagar Pudi, Nov 24 '14 at 15:13

score 1 · Answer 1 · answered Nov 24 '14 at 15:05

Create a Hashmap object, with key Long and value List. Add items with put(key,value) and retrieve them with get

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class Main {    
    public static void main(String[] args) {
        Map<Long,List<String>> myMap=new HashMap<Long,List<String>>();
        List<String> myList=new ArrayList<String>();
        myList.add("abc");
        myList.add("xyz");
        myMap.put(new Long(1), myList);
        for(int i=0;i<myList.size();i++)
            System.out.println(myMap.get(new Long(1)).get(i));
    }
}

score 0 · Answer 2 · edited Apr 18 '18 at 02:43

0

1.) Create HashMap with Key as Long and value as List<String>.

2.) Use put method of HashMap, as below.

 public static void main(String[] args) {
        Map<Long, List<String>> myMap = new HashMap<Long, List<String>>();
        myMap.put(101L, new ArrayList<String>());
    }

edited Apr 18 '18 at 02:43

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answered Nov 24 '14 at 15:05

Ankur Singhal

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How to add List of objects in a Map

2 Answers2