CODEWITHSUNDEEP
javajsondictionaryarraylisthashmap
learner
learner

Reputation: 94

Merge arraylist of maps in json, java

I have 2 arraylists(of same size) in json as below:

List<HashMap<String, String>> list1 = new Arraylist<HashMap<String, String>>();

List<HashMap<String, String>> list2 = new Arraylist<HashMap<String, String>>();

I want to merge the above lists into a single one.

For ex:

List1:

[{ " key1": "value1", " key2": "value2"}, 
{ " key11": "value11", " key22": "value22"}]

List2:

[{ " key3": "value3"},{" key33": "value33"}]

Expected output:

[{ " key1": "value1", " key2": "value2", " key3": "value3"}, 
{ " key11": "value11", " key22": "value22", " key3": "value3"}]

An early response will be highly appreciated. Thanks a lot in advance.

Upvotes: 0

Views: 92

Answers (4)

Muhammad Suleman
Muhammad Suleman

Reputation: 2922

Edit: you can do like this

    for (HashMap<String, String> m : list2) {
        HashMap<String, String> t = list1.get(list2.indexOf(m));
        for(String key: t.keySet()){
            m.put(key, t.get(key));
        }
    }

Now Merged items are in list2.

Upvotes: 0

Abi
Abi

Reputation: 1345

You Just have to retrieve the Hashmap from the individual Lists and then merge them all together

for eg

HashMap m = new HashMap();
        m.put("key1", "val1");
        m.put("key2", "val2");

        HashMap m1 = new HashMap();
        m1.put("key3", "val3");
HashMap mergeMap = new HashMap();
        mergeMap.putAll(m);
        mergeMap.putAll(m1);

        System.out.println("Map:" + mergeMap);

Output

Map:{key3=val3, key2=val2, key1=val1}

Upvotes: 0

Eric Wei
Eric Wei

Reputation: 61

Your expected output probably be:

[{ " key1": "value1", " key2": "value2", " key3": "value3"}, { " key11": "value11", " key22": "value22", " key33": "value33"}]

You didn't indicate whether two lists had same size or not. According to your example, I assumed the lists had same size. So the code could be like below:

for (int i = 0; i < list1.size(); i++) {
  list1.get(i).putAll(list2.get(i));
}

Upvotes: 1

Wakachopo
Wakachopo

Reputation: 149

If the two ArrayList have the same type (they seem to be arraylist of maps): 

 list1.addAll(list2)

Upvotes: 2

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