Java Arraylist Data extraction

Question

How would you extract the data as follows:

I want to extract from this arraylist:

[{itemname=Original, number=12}, {itemname=BBQ, number=23}, {itemname=C         


        

Answer 1

To extract the data as you expected, you can use Jackson JSON processor. It allows you to read and write JSON easily. You can follow their tutorial here.

Fist you have to download the relevant jar files(2 files) provided by them.

So the following code snippet should solve your problem, and the result is written to the jsonResult.json file.

    String[] chips = {"Original", "BBQ", "CatchUp"};
    String[] chipentry = {"12", "23", "23"};

    List> list = new ArrayList>();
    for (int i = 0; i < 3; i++) {
        HashMap map = new HashMap();
        map.put("itemname", chips[i]);
        map.put("number", chipentry[i]);
        list.add(map);
    }

    ObjectMapper mapper = new ObjectMapper();
    Map untyped = new HashMap();

    untyped.put("result", list);
    mapper.writeValue(new File("jsonResult.json"), untyped);

And following is the output of the file,

{"result":[{"itemname":"Original","number":"12"},{"itemname":"BBQ","number":"23"},{"itemname":"CatchUp","number":"23"}]}