Thread: how do you change the datatype of an attribute from String to Array?

I'm having a difficulty. I want to modify an attribute's data type from String to Array.

{
    “id”: “trn:tarb:tradingpartner:uuid:00000464-fa72-49fe-b050-c4bf1cfd8259”,
    “partnerNumber”: “1098981”,
    “partnerName”: "AFLO ",
    “currencyCode”: “GBP”,
    “commercialPartnerStatus”: “Inactive”,
    “source”: {
        “id”: “STV0001$$”,
        “name”: “QS”
    },
    “corpCode”: “DR”,
    “subCorpCode”: “001”,
    “targetMarket”: “UK”
}

In the preceding one, I want to convert targetMarket from String to Array without affecting its name.

 “targetMarket”:[
    “UK”,
    “IN”
]

The issue is with the old data, which is in string format, and if I alter the attribute in java, I receive an error while retrieving data from the database. It cannot automatically cast from string to ArrayList. I saw a method on this page but I'm confused is it compatible here or not? https://www.scaler.com/topics/string-to-array-in-java/
As a result, I must first change the old data before changing the java code. It is also acceptable if data is null or removed after changing the object from string to array.

Array are declared as values in a single string. Such as "STP"

 
String [ ] country = {"UK", "IN"} // the string value already converts it when you declare it like this