这是我在 StackOverflow 上的第一个问题,很抱歉问题的表述不准确。
这是 logcat 中的 Json :
I/Result is: null{"coord":{"lon":-0.13,"lat":51.51},"weather":[{"id":300,"main":"Drizzle","description":"light intensity drizzle","icon":"09d"}],"base":"stations","main":{"temp":280.32,"pressure":1012,"humidity":81,"temp_min":279.15,"temp_max":281.15},"visibility":10000,"wind":{"speed":4.1,"deg":80},"clouds":{"all":90},"dt":1485789600,"sys":{"type":1,"id":5091,"message":0.0103,"country":"GB","sunrise":1485762037,"sunset":1485794875},"id":2643743,"name":"London","cod":200}
这是我的代码:
public class MainActivity extends AppCompatActivity {
String weather,id,result;
public class DownloadTask extends AsyncTask<String,Void,String>{
@Override
protected String doInBackground(String... urls) {
try {
URL url = new URL(urls[0]);
HttpURLConnection httpURLConnection = (HttpURLConnection) url.openConnection();
InputStream inputStream = httpURLConnection.getInputStream();
InputStreamReader inputStreamReader = new InputStreamReader(inputStream);
int data = inputStreamReader.read();
while(data != -1){
char count = (char) data;
result += count;
data = inputStreamReader.read();
}
return result;
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return null;
}
@Override
protected void onPostExecute(String result) {
super.onPostExecute(result);
try {
JSONObject jsonObject = new JSONObject(result);
String res = jsonObject.getString("coord");
Log.i("Result is ",res);
} catch (JSONException e) {
e.printStackTrace();
}
}
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// Toast.makeText(this, id, Toast.LENGTH_SHORT).show();
DownloadTask task = new DownloadTask();
task.execute("http://samples.openweathermap.org/data/2.5/weather?q=London,uk&appid=b1b15e88fa797225412429c1c50c122a1");
}
}
这是异常(exception):
W/System.err: org.json.JSONException: Value null of type org.json.JSONObject$1 cannot be converted to JSONObject
最佳答案
用空初始化结果字符串
String result="";
您的结果字符串是类变量,所有字符串默认都使用 =null
值初始化
下面一行添加到null+yourResponse
result += count;
关于java - 如何从 null JSONObject 获取数据?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/46127487/