如何使用简单的 JSON 库读取 json 文件（数组形式）？

Question

Actually, The example below is an answer somewhere in StackOverFlow. I tried to use the below code, but,

JSONArray a = (JSONArray) parser.parse(new FileReader("c:\\exer4-courses.json"));

Above line doesn't work because of the below Exception.

java.lang.ClassCastException: org.json.simple.JSONObject cannot be cast to org.json.simple.JSONArray

Is there any way to read my JSON file?

JSON file:

[
    {
        "name": "John",
        "city": "Berlin",
        "cars": [
            "audi",
            "bmw"
        ],
        "job": "Teacher"
    },
    {
        "name": "Mark",
        "city": "Oslo",
        "cars": [
            "VW",
            "Toyata"
        ],
        "job": "Doctor"
    }
]

Java code:

JSONArray a = (JSONArray) parser.parse(new FileReader("c:\\exer4-courses.json"));

for (Object o : a) {
    JSONObject person = (JSONObject) o;

    String name = (String) person.get("name");
    System.out.println(name);

    String city = (String) person.get("city");
    System.out.println(city);

    String job = (String) person.get("job");
    System.out.println(job);

    JSONArray cars = (JSONArray) jsonObject.get("cars");

    for (Object c : cars) {
      System.out.println(c + "");
    }
  }

Answer 1

The exception is quite clear. You need to cast to JSONObject and not JSONArray

JSONObject a = (JSONObject) parser.parse(new FileReader("c:\\exer4-courses.json"));

You could possibly have this structure for your JSON:

{
   "records": [
      {
         "name": "John",
         "city": "Berlin",
         "cars": [
            "audi",
            "bmw"
         ],
         "job": "Teacher"
      },
      {
         "name": "Mark",
         "city": "Oslo",
         "cars": [
            "VW",
            "Toyata"
         ],
         "job": "Doctor"
      }
   ]
}

Now to iterate you can do:

JSONArray records = (JSONArray)a.get("records");

for (Object o : records) {
    JSONObject person = (JSONObject) o;

    String name = (String) person.get("name");
    System.out.println(name);

    String city = (String) person.get("city");
    System.out.println(city);

    String job = (String) person.get("job");
    System.out.println(job);

    JSONArray cars = (JSONArray) jsonObject.get("cars");

    for (Object c : cars) {
      System.out.println(c + "");
    }
  }