How to read and write a HashMap to a file?

Question

I have the following HashMap:

HashMap fileObj = new HashMap();

ArrayList cols         


        

Answer 1

you can also use JSON file to read and write MAP object.

To write map object into JSON file

    ObjectMapper mapper = new ObjectMapper();

    Map map = new HashMap();
    map.put("name", "Suson");
    map.put("age", 26);

    // write JSON to a file
    mapper.writeValue(new File("c:\\myData.json"), map);

To read map object from JSON file

    ObjectMapper mapper = new ObjectMapper();

        // read JSON from a file
        Map map = mapper.readValue(
                new File("c:\\myData.json"),
                new TypeReference>() {
        });

        System.out.println(map.get("name"));
        System.out.println(map.get("age"));

and import ObjectMapper from com.fasterxml.jackson and put code in try catch block