Convert JSON Array of Objects to List<String>

Question

I'm having a piece of that selecting data in JSON and I want to convert it to Java ArrayList.

String q = "SELECT attributes FROM common_attr_test";
PreparedStatement preparedStatement = (PreparedStatement) conn.prepareStatement(q);
preparedStatement.execute();
ResultSet rs = preparedStatement.executeQuery();
while (rs.next()) {
    valueAttributes = rs.getString("attributes");
} 

JSONObject obj=(JSONObject)JSONValue.parse(valueAttributes); 
JSONArray arrOne=(JSONArray)obj.get("1"); 
System.out.println(arrOne);

From the code, I get the below result:

[{"entry":"1","count":1},{"entry":"2","count":1},{"entry":"3","count":1}]

I try to code using

ArrayList<String> listOne = new ArrayList<String>();

if (arrOne != null) { 
    int len = arrOne.size();
    for (int i=0;i<len;i++){ 
        listOne.add(arrOne.get(i).toString());
    } 
} 
System.out.println(arrOne);
System.out.println("\nlistOne:"+listOne);

and getting the result :

[{"entry":"2","count":3}]

My question is how am I going to put the result into an ArrayList in Java like below :

[(1,1),(2,1),(3,1)]

try using gson or jackson library, that'll make things a lot easier for you — Afaq Ahmed Khan
– Afaq Ahmed Khan, Commented Sep 27, 2018 at 7:00

Bentaye · Accepted Answer · 2018-09-27 07:56:37Z

1

You need go through your JSONArray, cast each element into a JSONObject and extract the entry and count values from each one, then make a string out of them and add to your list:

if (arrOne != null) {
    JSONObject entryCountJson;
    String entry, count;
    for (Object o : arrOne) {
        entryCountJson = (JSONObject) o;
        entry = String.valueOf(entryCountJson.get("entry"));
        count = String.valueOf(entryCountJson.get("count"));
        listOne.add("(" + entry + "," + count + ")");
    }
}
System.out.println("arrOne: "+arrOne);
System.out.println("listOne: "+listOne);

This outputs:

arrOne: [{"entry":"1","count":1},{"entry":"2","count":1},{"entry":"3","count":1}]
listOne: [(1,1), (2,1), (3,1)]

answered Sep 27, 2018 at 7:56

Bentaye

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