Develop Reference

How to read JSON file in Java with simple json?

If I have a JSON like this:
{
"name": "Johnny",
"Gender": {
"male": true,
"female": false
},
"What does Johnny likes?": ["Travels", "Woman"],
"Travels": [
{
"Country": "Spain",
"City": "Madrid"
},
{
"Country": "Greece",
"City": "Kalokairi"
}
]
}
I know that I can do this to access to name:
object.getString("name");
To access gender I can do this:
JSONObject gender = (JSONObject) object.get("Gender");
gender.get("male");
gender.get("female");
To access What does Johnny likes? I can:
JSONArray likes = (JSONArray) objet.get("What does Johnny likes?");
Iterator<String> iterator = likes.iterator();
while (iterator.hasNext()) {
//code here
}
But how do I access Travels? I'm really not sure to understand it?

did you, try this?
JSONArray travels = (JSONArray) objet.get("Travels");
for(int j=0;j<travels.length();j++){
JSONObject travel = travels.getJSONObject(j);
}

How to Create a JSONArray using JSONObject with all values from a database table in java

I am fetching details from a database table which contains 3 rows in JAVA.
I am using JSONarray and JSONObject as follows
JSONObject jsonObject = new JSONObject();
JSONObject mainjsonObject = new JSONObject();
JSONArray ja=new JSONArray();
The data from table is put to the jsonObject as follows for each one:
String qry="select * from details";
ResultSet res = select .executeQuery(qry);
while(res.next){
String Name=res.getString("name");
.
.
jsonObject.put("Name", Name);
.
.
ja.put(jsonObject);
}
mainjsonObject.put("PERSONAL DETAILS",ja);
i should get the output json as follows:
{
"PERSONAL DETAILS": [
{
" name": "abc",
"age": "4",
"gender": "F",
"Place": "abc1"
},
{
" name": "xyz",
"age": "3",
"gender": "M",
"Place": "abc2"
}
]
}
But am getting same values in both like below:
{
"PERSONAL DETAILS": [
{
" name": "abc",
"age": "4",
"gender": "F",
"Place": "abc1"
},
{
" name": "abc",
"age": "4",
"gender": "F",
"Place": "abc1"
}
]
}
Please help me with a solution. I need to get all the values from the tables as an array in JSON format

you need to create new JSONObject in your loop otherwise the last record will be shown everywhere
while(res.next()){
String Name=res.getString("name");
jsonObject = new JSONObject();
// ^^^^^^^^
jsonObject.put("Name", res.getString(1));
jsonObject.put("age", res.getString(2));
jsonObject.put("gender", res.getString(3));
jsonObject.put("Place", res.getString(4));
ja.put(jsonObject);
}

The problem is that you are reusing the same JSONObject over and over. And this is basically a Map.
What you need to do is create a new JSONObject instance and put it in the array for each iteration:
JSONObject obj;
while (rs.next()) {
obj = new JSONObject();
// fill in obj
ja.put(obj);
}

should value must be quoted in JSON along with key

i have data
like this:
{
"status": "success",
"message": "Student Statement Report",
"data": {
"data": [{
"id": "45",
"transaction_no": "45",
"transaction_date": "2017-05-25",
"transaction_type": "invoice",
"transaction_amount": "1010.00",
"related_invoice_id": "45",
"balance_amount": "1010.00",
"related_user_id": "436",
"related_user_group": "student",
"description": "",
"created_by": "Principal",
"updated_by": "Principal",
"created_at": "2017-05-25 11:57:39",
"updated_at": "2017-05-25 11:57:39"
}],
"opening_balance": 0,
"dates": ["2017-05-22 00:00:00", "2017-05-28 23:59:59"]
}
}
JSONObject jsonObject = new JSONObject(response);
and i am geeting Json expection error from here
String openingBalance = jsonObject.getString("opening_balance");
"opening_balance": 0,
so, my biggest question is should that zero (value) should be quoted or not?

You have to parse it like this:
JSONObject jsonObject = new JSONObject(response);
JSONObject data = jsonObject.getJSONObject("data");//Get Data object
int openingBalance = data.getInt("opening_balance");//Get opening balance

If you read the number as an Integer then quotation is not necessary. But if your read it as a String then you have to put quotation.
To read as an Integer you can use getInt("json_key")
& for String getString("json_key").

JSONObject jsonObject = new JSONObject(response);
JSONObject data = jsonObject.getJSONObject("data");//Get Data object
int openingBalance = data.getInt("opening_balance");//Get opening balance

Join two jsons based on element

I have two json files. I need to parse and join the json into a single structure
lineage.json
{
"lineage": [{
"sourceColumnId": "VMB_BESTADDRESS.SNAPSHOT_TS",
"description": "",
"targetColumnId": "VMB_BESTADDRESSUSAGE.NXREINS"
},
{
"sourceColumnId": "DSL_RECORD_SOURCES.MAMACT",
"description": "",
"targetColumnId": "G2_ZUMADF00.MAMACT"
},
{
"sourceColumnId": "DSL_RECORD_SOURCES.MAMADE",
"description": "",
"targetColumnId": "G2_ZUMADF00.HDF_S_POL_GEN"
}]
}
column.json
{
"column": [{
"ID": 39700,
"columnId": "VMB_BESTADDRESS.SNAPSHOT_TS",
"column": "SNAPSHOT_TS",
"dataType": "String",
"length": "",
"table": "VMB_BESTADDRESS",
},
{
"ID": 39701,
"columnId": "VMB_BESTADDRESSUSAGE.NXREINS",
"column": "NXREINS",
"dataType": "String",
"length": "",
"table": "VMB_BESTADDRESSUSAGE",
},
{
"ID": 39702,
"columnId": "VMB_BESTADDRESSUSAGE.PKADDRESSCODE",
"column": "PKADDRESSCODE",
"dataType": "String",
"length": "",
"table": "VMB_BESTADDRESSUSAGE",
}]
}
I need to join the two jsons such that for every match of sourcecolumnId and targetcolumnid in column the following json structure must be populated
{
output:{
sourceColumnId:VMB_BESTADDRESS.SNAPSHOT_TS,
sourceColumnName:SNAPSHOT_TS,
targetColumnId:VMB_BESTADDRESSUSAGE.NXREINS,
targetColumnNameNXREINS,
}
}
I need to join lookup two json to get the output such that
sourceColumnName -> column name from column.json whose columnId and sourceColumnId are same.
similarly for targetcolumnName also.

String str = "xxx"; // column.json
JSONArray jsonArrayColumn = JSON.parseObject(str);
Map<String, JSONObject> column = new HashMap(); // {id:name}
for(int i = 0; i < jsonArrayColumn.size(); i++){ // loop
JSONObject obj = jsonArrayColumn.getJSONObject(i);
column.put(obj.getString("columnId"), obj.getString("column"));
}
String str2 = "xxx"; // lineage.json
JSONArray jsonArrayLineage = JSON.parseObject(str2);
JSONArray resultArray = new JSONArray();
for(int i = 0; i < jsonArrayLineage.size(); i++){ // loop
JSONObject lineageObj = jsonArrayLineage.getJSONObject(i);
JSONObject obj = new JSONObject();
obj.put("sourceColumnId", lineageObj.get("sourceColumnId"));
obj.put("sourceColumnName", column.get(lineageObj.get("sourceColumnId")));
obj.put("targetColumnId", lineageObj.get("targetColumnId"));
obj.put("targetColumnName", column.get(lineageObj.get("targetColumnId")));
}
The resultArray is what you want.

Parsing jsonobject when entire json is an array?

I am using gson-2.5 for this. There is a slight difference in the format of these two jsons, where in the first one;
"usethis": [
{
"id": 111,
"text": "some text that i would like",
},
{
"id": 222,
"text": "someothertextiwouldlike",
}
]
I would have parsed this to get "text" this way, and everything would be ok;
JsonParser jp = new JsonParser();
JsonElement root = jp.parse(listcontents);
JsonObject rootobj = root.getAsJsonObject();
JsonArray items = rootobj.get("usethis").getAsJsonArray();
for(int i = 0; i < items.size(); i++) {
JsonObject item = items.get(i).getAsJsonObject();
String thetext = item.get("text").getAsString();
System.out.println("text: " + thetext + "\n");
}
The difference is that in the second one, I have nothing to get as the rootobject unlike in the first where I used "usethis";
[
{
"id": 111,
"text": "some text that i would like",
},
{
"id": 222,
"text": "someothertextiwouldlike",
}
]
And setting
rootobj.get("usethis").getAsJsonArray();
to
rootobj.get("").getAsJsonArray();
just gives me an error. How would I be able to parse the second json?

JsonElement is just a superclass of JsonArray and JsonObject.
JsonArray items = root.getAsJsonArray();
should do what you want.