Iterating through nested Json Array and performing operations on String Java

Question

I have json array in this format

    [
{
    "promise_detail": [
        {
            "promise_date": "15 OCT 2020",
            "promise_amount": "USD 1086",
            "status": "CANCELLED"
        }
    ],
    "promise_note": "hello"
}

]

My requirement is i need to loop through Json array and format promise amount field to two decimal places which looks like "USD 1086.00"

Here is what i am trying to do

    result = executeQueries.getPromiseHistoryDetails(promiseHistoryModel);//Here result is same Json Array as shown above
    for (int n = 0; n < result.length(); n++) {
            JSONObject object = result.getJSONObject(n);
            for(int k=0;k<object.length();k++) {  //struck here
                String promiseAmount = object.getJSONObject(k);
                Float amount=Float.parseFloat(promiseAmount);
                if (object.get("promise_amount") != null) {
                    DecimalFormat df = new DecimalFormat("0.00");
                    df.setMaximumFractionDigits(2);
                    result.getJSONObject(n).put("promise_amount", df.format(amount));
                }
            }
            
        }

But I am getting some issues.I am struck at this point.Can anyone suggest me how i can achieve this.This is my expected output

    [
{
    "promise_detail": [
        {
            "promise_date": "15 OCT 2020",
            "promise_amount": "USD 1086.00",
            "status": "CANCELLED"
        }
    ],
    "promise_note": "hello"
}
]

The documentation is your friend. It shows that DecimalFormat inherits two format methods from NumberFormat: format(double) and format(long). You are trying to format a String, but the methods only accept numbers. — VGR
– VGR, Commented Oct 7, 2020 at 13:13
Getting closer. Now, it should be obvious from the exception you’re getting that the characters USD do not constitute a valid float value. Use the substring method to obtain text consisting of only the numeric value. — VGR
– VGR, Commented Oct 7, 2020 at 14:47

LHCHIN · Accepted Answer · 2020-10-08 03:44:54Z

1

It seems you mixed up the operation of JSONArray with JSONObject. The inner for-loop is supposed to traverse a JSONArray rather than a JSONObject.

And the format of promise_amount in your given JSON string is a String, so you can just append .00 to the origin value as follows:

Code snippet

for (int n = 0; n < result.length(); n++) {
    JSONArray object = result.getJSONObject(n).getJSONArray("promise_detail");
    for (int k = 0; k < object.length(); k++) {
        String promiseAmount = object.getJSONObject(k).getString("promise_amount");
        if (promiseAmount != null) {
            object.getJSONObject(k).put("promise_amount", String.format("%s.00", promiseAmount));
        }
    }
}

answered Oct 8, 2020 at 3:44

LHCHIN

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LHCHIN Over a year ago

@Sachin HR Please let me know if my solution works for you, thanks!

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