How to Extract \'id\' and \'loc\' Values from a Nested JSONArray in Java?

Accessing "id" and "loc" Values from a Nested JSONArray in Java

When parsing JSON data in Java, it's common to encounter nested structures, such as JSONArrays within JSONObjects. Accessing specific values within these nested structures can be a bit tricky for beginners.

Problem:

Consider the following JSON data:

{
  "locations": {
    "record": [
      {
        "id": 8817,
        "loc": "NEW YORK CITY"
      },
      {
        "id": 2873,
        "loc": "UNITED STATES"
      },
      {
        "id": 1501,
        "loc": "NEW YORK STATE"
      }
    ]
  }
}

The goal is to iterate through the "record" JSONArray and access the "id" and "loc" values for each record.

Solution:

To access the members of an item in a JSONArray, you can use the getJSONObject(int) method. The following code demonstrates how to achieve this:

JSONObject req = new JSONObject(join(loadStrings(data.json),""));
JSONObject locs = req.getJSONObject("locations");
JSONArray recs = locs.getJSONArray("record");

for (int i = 0; i < recs.length(); ++i) {
    JSONObject rec = recs.getJSONObject(i);
    int id = rec.getInt("id");
    String loc = rec.getString("loc");
    // ...
}

Within the for-loop:

• recs.length() provides the number of elements in the "record" JSONArray.
• recs.getJSONObject(i) returns a JSONObject representing the i-th record.
• rec.getInt("id") retrieves the integer value of the "id" key.
• rec.getString("loc") retrieves the string value of the "loc" key.

These retrieved values can then be used for further processing or operations.

The above is the detailed content of How to Extract \'id\' and \'loc\' Values from a Nested JSONArray in Java?. For more information, please follow other related articles on the PHP Chinese website!