How to convert ArrayList of custom class to JsonArray in Java?

Question

I am trying to convert ArrayList of custom class to JsonArray. Below is my code. It executes fine but some JsonArray elements come as zeros even though they are numbers in the A

Answer 1

Use google gson jar, Please see sample code below,

    public class Metric {
        private int id;
        ...
       setter for id
        ....
       getter for id
    }

    Metric metric = new Metric();
    metric.setId(1);

    GsonBuilder gsonBuilder = new GsonBuilder();
    gsonBuilder.serializeNulls();
    Gson gson = gsonBuilder.create();
    System.out.println(gson.toJson(metric));

StringBuffer jsonBuffer = new StringBuffer("{ \"rows\": [");
List metrices = new ArrayList();
// assume you have more elements in above arraylist
boolean first = true;
for (Metric metric : metrices) {
       if (first)
      first = false;
    else
      jsonBuffer.append(",");
      jsonBuffer.append(getJsonFromMetric(metric));
}
jsonBuffer.append("]}");

private String getJsonFromMetric(Metric metric) {
GsonBuilder gsonBuilder = new GsonBuilder();
    gsonBuilder.serializeNulls();
    Gson gson = gsonBuilder.create();
    return gson.toJson(metric);
}