I am now currently using a weather API from http://wiki.swarma.net/index.php?title=%E5%BD%A9%E4%BA%91%E5%A4%A9%E6%B0%94API/v2 and wished to convert the JSONObject into printable Strings. However, when I am working on the following code, two errors occurred:
public class getApi {
private static final String WEATHER_MAP_URL = "https://api.caiyunapp.com/v2/TAkhjf8d1nlSlspN/121.6544,25.1552/realtime.json";
private static final String WEATHER_TEST_API = "TAkhjf8d1nlSlspN";
public static JSONObject getWeatherJson() {
try {
URL url = new URL( WEATHER_MAP_URL );
HttpURLConnection connection =
(HttpURLConnection)url.openConnection();
connection.addRequestProperty( "x-api-key", WEATHER_TEST_API );
BufferedReader reader = new BufferedReader(
new InputStreamReader( connection.getInputStream()) );
StringBuffer json = new StringBuffer( 1024 );
String tmp;
while( (tmp = reader.readLine()) != null )
json.append(tmp).append("\n");
reader.close();
JSONObject data = new JSONObject( json.toString() );
if(data.getJSONObject("status").toString() != "ok" ) {
return null;
}
return data;
}
catch(Exception e) {
e.printStackTrace();
return null;
}
}
public static void main( String[] args ) {
JSONObject WeatherJson = getWeatherJson();
try {
JSONArray details = WeatherJson.getJSONObject("result").getJSONObject("hourly").
getJSONArray("skycon");
System.out.println(details.getJSONObject(0).getJSONObject("value").toString());
} catch (JSONException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
The JSONObject structure, which is also shown in the link above, is like this:
{
"status":"ok",
"lang":"zh_CN",
"server_time":1443418212,
"tzshift":28800,
"location":[
25.1552, //latitude
121.6544 //longitude
],
"unit":"metric",
"result":{
"status":"ok",
"hourly":{
"status":"ok",
"skycon":[
{
"value":"Rain",
"datetime":"2015-09-28 13:00"
},
{
...
}]
}
}
}
The error occurred:
org.json.JSONException: JSONObject["status"] is not a JSONObject.
at org.json.JSONObject.getJSONObject(JSONObject.java:557)
at getApi.getWeatherJson(getApi.java:34)
at getApi.main(getApi.java:45)
Exception in thread "main" java.lang.NullPointerException
at getApi.main(getApi.java:47)
I have looked at similar posts on the topic is not a JSONObject Exception
but found that none of them can help me. I suspect that something is wrong with requesting the data, so actually, getWeatherJson()
returns a null object and results in the NullPointerException
and JSONObjectException
.
Can anyone help me with the code?
According to the getJSONObject()
Javadoc , this method will throw an exception if the returned object isn't a true JSON object, which it isn't because "status" is a string. As such, try using data.getString("status")
.
The status field in the JSON document you have posted is not an object. In JSON, objects are enclosed in with {}
brackets. The result node however, is a nested object which holds the status key/value pair. Try the following:
JSONObject data = new JSONObject(json.toString());
if(data.getJSONObject("result").get("status").toString() != "ok" ) {
return null;
}
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