Store JSON array value in HashMap and remove duplicate

Question

I have a JSON response which look something like this( its different from user to user)

{
 "success": true, "data": 
 [
    {
    "mandatory_tag": "My Company",
    "id": "topic_1408946825893148"  
    },
    {
    "mandatory_tag": "Partners",
    "id": "topic_1408946942491149",
    },
    {
    "mandatory_tag": "Industry",
    "id": "topic_1408946996510150",
    }, 
    {
    "mandatory_tag": "Competitors",
    "id": "topic_1409210454810358",
    }, 
    {
    "mandatory_tag": "Competitors",
    "id": "topic_1408947133657152"
    }, 
    {
    "mandatory_tag": "Competitors",
    "id": "topic_1408947071457151",
    }, 
    {
    "mandatory_tag": "Competitors",
    "id": "topic_1409210621754362",
    }, 
    {
    "mandatory_tag": "Competitors",
    "id": "topic_1409210704390363",
    }, 
    {
    "mandatory_tag": "Competitors",
    "id": "topic_1409210794791364"
    }
  ]
}

I am parsing it and trying to store in HashMap, but the key value is duplicating. Can anyone suggest me how can i store all id with same mandatory_tag in one array?

I am new to this so please consider..thanks

                  try
                    { 
                        JSONObject jsonMain = new JSONObject(jsonString);
                        JSONArray dataArray = jsonMain.getJSONArray("data");
                        for(int i = 0; i < dataArray.length(); i++)
                        {
                            JSONObject tagObject = dataArray.getJSONObject(i);
                            String mandatory_tag = tagObject.getString("mandatory_tag");
                            String id = tagObject.getString("id");
                            List<String> arrayID = new ArrayList<String>();
                            if(myMap.containsKey(mandatory_tag))
                            {
                                arrayID.add(id);
                                myMap.put(mandatory_tag, arrayID);
                            } else
                            {
                                List<String> newArrayID = new ArrayList<String>();
                                newArrayID.add(id);
                                myMap.put(mandatory_tag, newArrayID);
                            }
                     }

And well i got stuck at this now..any good logic please..

L. Young · Accepted Answer · 2014-09-16 08:45:33Z

1

A hashmap allows you to store key-value items. I would suggest the HashMap be of type <String,List<String>> so allowing you to store items with the same mandatory_tag in the same list under 1 key.

For example

HashMap<String,List<String>> myMap = new HashMap<String,List<String>>();

if (myMap.containsKey(mandatory_tag)) {
    List<String> values = myMap.get(mandatory_tag);
    if (values!=null) {
       values.add(id)
    } else {
        values = new List<String>();
        values.add(id);
    }
}

Update

As I wrote in my comment below, the except you added has an error

List<String> arrayID = new ArrayList<String>();
                        if(myMap.containsKey(mandatory_tag))
                        {
                            arrayID.add(id);
                            myMap.put(mandatory_tag, arrayID);
                        }

What you are doing here is, if the map already contains the key you are replacing the value associated with the key with a new list which contains only 1 value. What you need to do is update the list of already existing values. Check the code below and make sure you understand the problem. These are fundamentals of programming and you need to understand the logic of what you're doing to advance.

//Somewhere you have declared your HashMap
HashMap<String,List<String>> myMap = new HashMap<String,List<String>>();

//then we continue with your excerpt  
try { 
JSONObject jsonMain = new JSONObject(jsonString);
JSONArray dataArray = jsonMain.getJSONArray("data");


for(int i = 0; i < dataArray.length(); i++) {
    JSONObject tagObject = dataArray.getJSONObject(i);
    String mandatory_tag = tagObject.getString("mandatory_tag");
    String id = tagObject.getString("id");

    if(myMap.containsKey(mandatory_tag)) {
         List<String> arrayID = myMap.get(mandatory_tag);
         arrayID.add(id);
    } else {
         List<String> newArrayID = new ArrayList<String>();
         newArrayID.add(id);
         myMap.put(mandatory_tag, newArrayID);
    }

}

edited Sep 16, 2014 at 8:45

answered Sep 15, 2014 at 8:46

L. Young

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4 Comments

L. Young Over a year ago

can u paste the code u are currently using to parse the JSON? mandatory_tag is a variable containing the mandatory_tag of the parsed JSON. myMap is the HashMap you create. The functions for HashMap are available here So you would need the containsKey(key) function

Julian Over a year ago

Hey Young, this is what i am trying now.. JSONObject jsonMain = new JSONObject(jsonString); JSONArray dataArray = jsonMain.getJSONArray("data"); for(int i = 0; i < dataArray.length(); i++) {JSONObject tagObject = dataArray.getJSONObject(i); String mandatory_tag = tagObject.getString("mandatory_tag"); String id = tagObject.getString("id"); if(myMap.containsKey(mandatory_tag)) { List<String> values = myMap.get(mandatory_tag); if (values!=null) {values.add(id); } else { values = new ArrayList<String>(); values.add(id);}}}

L. Young Over a year ago

@Julian is it not working for you? Please edit your original comment with the properly formatted code.

L. Young Over a year ago

@Julian your error start at List<String> arrayID = new ArrayList<String>(); What you are doing here and in the following if statement, when the condition is true, is that you are not adding your id to the already existing list of values but to a new list, and then replacing the old list with the new one. I've updated my original answer with the code.

Apoorv · Accepted Answer · 2014-09-15 08:42:47Z

0

Create a POJO called TagValues(or whatver name you would like) with variables mandatory_tag,id and then and create an ArrayList<TagValues> in which you can store all the objects.

answered Sep 15, 2014 at 8:42

Apoorv

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1 Comment

Julian Over a year ago

hey apoorv, thanks, but can you give some related reference..it wil be more helpfull.

Julian · Accepted Answer · 2014-09-16 08:32:05Z

0

Thanks for your response, but with help of you guys, i got the solution

`HashMap<String,List<String>> myMap = new HashMap<String,List<String>>();    
for(int i = 0; i < dataArray.length(); i++)
    {
        JSONObject tagObject = dataArray.getJSONObject(i);
        String mandatory_tag = tagObject.getString("mandatory_tag");
        String id = tagObject.getString("id");
        if(myMap.isEmpty())
        {
            arrayID = new ArrayList<String>();
            arrayID.add(id);
            myMap.put(mandatory_tag, arrayID);
        } 
        else if(myMap.containsKey(mandatory_tag))
        {
            arrayID.add(id);
            myMap.put(mandatory_tag, arrayID);
        }
        else
        {
            arrayID = new ArrayList<String>();
            arrayID.add(id);
            myMap.put(mandatory_tag, arrayID);
        }
    }`

answered Sep 16, 2014 at 8:32

Julian

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1 Comment

L. Young Over a year ago

you don't need to check if the map is empty. Also in the second if statement, where are you getting the arrayID from?

stealthjong · Accepted Answer · 2014-09-16 09:35:36Z

0

In those cases, I'd like to use a custom HashMap:

public MMap getData() {
    MMap result = new MMap();
    JSONArray array = getJSONArrayFromTotalJSON();
    for (int i = 0; i < array.length(); i++) {
        JSONObject obj = array.getJSONObject(i);
        String mtag = obj.getString(MANDATORY_TAG);
        String id = obj.getString(ID);
        result.put(mtag, id);
    }
    return result;
}

public class MMap extends HashMap<String, List<String>> {
    public void put(String key, String value) {
        if (!this.containsKey(key))
            this.put(key, new ArrayList<String>());
        this.get(key).add(value);
    }
}

edited Sep 16, 2014 at 9:35

answered Sep 16, 2014 at 9:28

stealthjong

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