Extract value using JSON Path from array

Question

I have Json like this below

{"pd":"{\"e\":{\"h\":{\"ak\":\"120\",\"at\":\"app\"},\"b\":[{\"ts\":1319549658547,\"tz\":-400,\"s\":\"StartUpScreen\",\"et\":8,\"ev\":\"sessionStart\",\"si\":\"19477682-de55-414f-82c9-19bec331dc33\",\"tt\":{\"day\":\"Tuesday\"}},{\"ts\":132,\"tz\":-400,\"s\":\"StartUpScreen\",\"et\":3,\"ev\":\"AutomaticFeedRefresh\",\"si\":\"19477682-de55-414f-82c9-19bec331dc33\",\"tt\":{}},{\"ts\":131,\"tz\":-400,\"s\":\"MainScreen\",\"et\":3,\"ev\":\"MainScreen Event\",\"si\":\"19477682-de55-414f-82c9-19bec331dc33\",\"tt\":{}}],\"tt\":{\"OSV\":\"7.10\"}}}","serverPayload":{"httpHeaders":{"x-bluecoat-via":["35D3468EFF4D5F18"],"content-type":["application\/x-www-form-urlencoded"]},"senderIp":["101.100.000.100"]}}

I just need the values of ak, b [ts,si and tt[day]] and senderIp. Now I have 2 questions, how do I extract all 'ts' attributes in 'b' and 'senderIp'. I have used the below code for ak, ts and si. I am not sure how I get 'tt', also while I run this code I get an exception like below

    String pd = JsonPath.read(jsonString, "$.pd");
    String ak = JsonPath.read(pd, "$e.h.ak");
    String ak = JsonPath.read(pd, "$e.h.b[0]");
//    String b = JsonPath.read(pd,"$.e.b[0][0]");
//    String b = JsonPath.read(pd,"$.e.b[0][5]");
    System.out.println("value of ak: "+ak);

Exception in thread "main" java.lang.ClassCastException: net.minidev.json.JSONObject cannot be cast to java.lang.String.

Answer 1

$.e.h.b[0] looks like a JavaScript object (with fields including "ts" and "tz"), not a string. So it's reasonable for your JSON parser to treat it as a JSONObject rather than a string. Probably you need to drill down to $.e.h.b[0].ts or whatever field you're interested in. Something like this:

long ts = JsonPath.read(pd, "$e.h.b[0].ts");

I'm assuming it's your second String ak = line which causes the exception. I'm having trouble understanding your other question about the "ts" attributes. Maybe you could format the JSON string for easier reading?