How To Convert A Map To Arraylist Of Objects?

Suppose I have having Json response like this: { 'status': true, 'data': { '29': 'Hardik sheth', '30': 'Kavit Gosvami' } } I am using Retrofit to parse Json respons

Solution 1:

If you can expand your class to have a constructor taking the values as well:

map.entrySet()
   .stream()
   .map(e -> new PojoObject(e.getKey(), e.getValue()))
   .collect(Collectors.toList());

If you can't:

map.entrySet()
   .stream()
   .map(e -> {
       PojoObject po = new PojoObject();
       po.setMapKey(e.getKey());
       po.setMapValue(e.getValue());
       return po;
 }).collect(Collectors.toList());

Note that this uses Java 8 Stream API.

Solution 2:

Looks like Java has exact POJO Map.Entry like you want. Hence, you can extract the entry set from map and iterate over the entry set like below or you can further convert the set to list like in next snippet and continue with your processing.

//fetch entry set from mapSet<Entry<String, String>> set = map.entrySet();        

    for(Entry<String, String> entry: set) {
        System.out.println(entry.getKey() +"," + entry.getValue());
    }

    //convert set to listList<Entry<String, String>> list = newArrayList(set);

    for(Entry<String, String> entry: list) {
        System.out.println(entry.getKey() +"," + entry.getValue());
    }

Solution 3:

Try this

List<Value> list = new ArrayList<Value>(map.values());

Or

hashMap.keySet().toArray(); // returns an array of keys
hashMap.values().toArray(); // returns an array of values

Should be noted that the ordering of both arrays may not be the same.

or

hashMap.entrySet().toArray();

Solution 4:

You can use this method to convert map to list

List<PojoObject> list = new ArrayList<PojoObject>(map.values());

Assuming:

Map <Key,Value> map;

Solution 5:

ArrayList<Map<String,String>> list = newArrayList<Map<String,String>>();

this may be the best way.