如何将对象添加到 JSONArray

Question

I want to add an object to an array. If the data of other_amount is more than zero I want to add one object more. If it's equal to zero, it should add nothing. This is my code:

JSONArray acc_data = new JSONArray();
Map<String, Object> myaccount = new LinkedHashMap<>();
for (int i = 0; i < mpay.size(); i++) {
    if(other_amount>0){
        myaccount.put("poAccount", other_account);
        myaccount.put("poAmount", other_amount);
        system.out.println(myaccount);
        //{poAccount=050017, poAmount=12}
    }

    myaccount.put("poAccount", amount_account);
    myaccount.put("poAmount", amount);
    system.out.println(myaccount);
    //{"poAccount":"050016","poAmount":"800"}

    acc_data.add(myaccount);
    system.out.println(acc_data);
    //[{"poAccount":"050016","poAmount":"800"}]
}

But I need it like this:

//[{"poAccount":"050016","poAmount":"800"},{poAccount=050017, poAmount=12}]

please help me to resolve it.

Answer 1

You shouldn't use map for your case. When your put the pair with existing in map key, the pair will be overwrited. For example

map.put ("k1","v1");

Map contains one pair "k1":"v1" The next call

map.put ("k1","newV1");

The first pair will be overwrited and map still contains 1 pair: "k1":"newV1"

For your case it's better to define simple POJO class with 2 fields poAccount and poAmount . And add them to the JSONArray

Answer 2

The approach you are following, it will not serve your requirement. You should use pojo to store the records and then populate the Json Array. You can have a look at this code and modify as per your requirements.

public class Test {

public static void main(String[] args) {

    Mypojo mypojo = new Mypojo();
    Gson gson = new Gson();
    JSONArray records = new JSONArray();
    for (int i = 0; i < 1; i++) {
        if (5 > 0) {
            mypojo.setPoAccount("050017");
            mypojo.setPoAmount("12");
            JSONObject objects = new JSONObject(gson.toJson(mypojo));
            records.put(objects);
        }

        mypojo.setPoAccount("050016");
        mypojo.setPoAmount("800");
        JSONObject objects = new JSONObject(gson.toJson(mypojo));
        records.put(objects);
    }

    System.out.println(records);

}

}

Mypojo Class :

public class Mypojo
{
private String poAmount;

private String poAccount;

public String getPoAmount ()
{
    return poAmount;
}

public void setPoAmount (String poAmount)
{
    this.poAmount = poAmount;
}

public String getPoAccount ()
{
    return poAccount;
}

public void setPoAccount (String poAccount)
{
    this.poAccount = poAccount;
}

@Override
public String toString()
{
    return "ClassPojo [poAmount = "+poAmount+", poAccount = "+poAccount+"]";
}
}