Develop Reference

How to parse JSON api using JAVA?

I am new on JAVA, how to parse the countryname using this API: https://iplist.cc/api
Use JAVA to parse the JSON: https://iplist.cc/api
Get ONLY the "countryname" value.
For example,
If the country name is "countryname": "Germany",
The OUTPUT should be only:
Germany
I tried this but did not work :(
public class JSONParser {
static InputStream is = null;
static JSONObject jObj = null;
static String json = "";
// constructor
public JSONParser() {}
public JSONObject getJSONFromUrl(String url) {
// Making HTTP request
try {
// defaultHttpClient
DefaultHttpClient httpClient = new DefaultHttpClient();
HttpPost httpPost = new HttpPost(url);
HttpResponse httpResponse = httpClient.execute(httpPost);
HttpEntity httpEntity = httpResponse.getEntity();
is = httpEntity.getContent();
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
} catch (ClientProtocolException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
try {
BufferedReader reader = new BufferedReader(new InputStreamReader(
is, "iso-8859-1"), 8);
StringBuilder sb = new StringBuilder();
String line = null;
while ((line = reader.readLine()) != null) {
sb.append(line + "\n");
}
is.close();
json = sb.toString();
} catch (Exception e) {
Log.e("Buffer Error", "Error converting result " + e.toString());
}
// try parse the string to a JSON object
try {
jObj = new JSONObject(json);
} catch (JSONException e) {
Log.e("JSON Parser", "Error parsing data " + e.toString());
}
// return JSON String
return jObj;
}
}
// url to make request
private static String url = "https://iplist.cc/api";
// JSON Node names
private static final String COUNTRY_NAME = "countryname";
// contacts JSONArray
JSONArray contacts = null;
// Creating JSON Parser instance
JSONParser jParser = new JSONParser();
// getting JSON string from URL
JSONObject json = jParser.getJSONFromUrl(url);
try {
country = json.getString(COUNTRY_NAME);
}
} catch (JSONException e) {
e.printStackTrace();
}
Thank You!

For such deserialization purpose, I would recommend you to use Gson (or another of this kind).
implementation 'com.google.code.gson:gson:2.8.6'
Prepare IP class for deserialization:
public class IP {
public final String ip;
public final String registry;
public final String countrycode;
public final String countryname;
public final String detail;
public final boolean spam;
public final boolean tor;
public IP(String ip, String registry,
String countrycode, String countryname,
String detail, boolean spam, boolean tor) {
this.ip = ip;
this.registry = registry;
this.countrycode = countrycode;
this.countryname = countryname;
this.detail = detail;
this.spam = spam;
this.tor = tor;
}
}
Deserialize from JSON String with Gson:
IP ip = new Gson().fromJson(json, IP.class);
System.out.println(ip.countryname);

First add org.json library to your project. this is for converting String to JSONObject.
public class HttpGet {
public static String readGetRequestData(String urlToRead) throws IOException {
// System.setProperty("https.proxyHost", "ip");
// System.setProperty("https.proxyPort", "port"); if you got some proxy set it
URL url = new URL(urlToRead);
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
connection.setRequestMethod("GET");
return new String(connection.getInputStream().readAllBytes(), StandardCharsets.UTF_8);
}
public static void main(String[] args) throws Exception {
String data = readGetRequestData("https://iplist.cc/api");
try {
JSONObject jsonObject = new JSONObject(data);
System.out.println(jsonObject.get("countryname"));
} catch (JSONException err) {
err.printStackTrace();
}
}
}
result is: Germany

HTTP response not giving output

I am working on an application that interacts with a room security control device.
I want to get devices information from API. I am using HttpUrlConnection and POST method. It hits the API and I get 200 OK response but I get the out
"{"json":{"control":{"cmd":"getdevice","uid":256}}} doesn't exist"
I have tried all the solutions from stackoverflow and other platforms but it's not giving the output.
Moreover I have tested this API on Postman and it's working there and giving the device information.
Here is the code:
public class HTTPRequestTask extends AsyncTask<Void, Void, Void> {
#Override
protected Void doInBackground(Void... params) {
String username = "admin";
String password = "888888";
URL url = null;
try {
url = new URL("http://192.168.100.25/network.cgi");
} catch (MalformedURLException e) {
e.printStackTrace();
}
assert url != null;
HttpURLConnection httpRequest = null;
try {
httpRequest = (HttpURLConnection) url.openConnection();
httpRequest.setRequestMethod("POST");
httpRequest.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
httpRequest.setDoInput(true);
httpRequest.setDoOutput(true);
android.util.Base64.encode(authString.getBytes(), android.util.Base64.DEFAULT);
httpRequest.addRequestProperty("Authorization", "Basic " + "YWRtaW46ODg4ODg4"); // This is auth bytecode
httpRequest.connect();
} catch (ProtocolException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
try {
JSONObject json = new JSONObject();
JSONObject jsonObject = new JSONObject();
JSONObject jsonObjectControl = new JSONObject();
jsonObjectControl.put("cmd","getdevice");
jsonObjectControl.put("uid",256);
jsonObject.put("control",jsonObjectControl);
json.put("json", jsonObject);
String encodedData = URLEncoder.encode( json.toString(), "UTF-8" );
BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(httpRequest.getOutputStream()));
writer.write(encodedData);
writer.flush();
BufferedReader bufferedReader = null;
bufferedReader = new BufferedReader
(new InputStreamReader(httpRequest.getInputStream(), "UTF-8"));
String line = null;
StringBuilder sb = new StringBuilder();
do {
line = bufferedReader.readLine();
sb.append(line);
Log.i("Output line: ",sb.toString());
}
while(bufferedReader.readLine()!=null);
bufferedReader.close();
int responseCode = httpRequest.getResponseCode();
String resMsg = httpRequest.getResponseMessage();
String result = sb.toString();
Log.d("Output: ","--"+result);
Log.d("Response Code: "+responseCode, "!!");
Log.d("Response MSG ","--"+resMsg);
} catch (IOException e) {
e.printStackTrace();
} catch (JSONException e) {
e.printStackTrace();
}
return null;
}
}

Getting partial Json response

I am getting a server side json response to load my menu, I tried twice and it gave this error message (the Error parsing data org.json.JSONException).
the reason for that is I'm getting the response partially, in both attempts i got different responses as shown in the images. i think I'm not getting the complete json response, getting only partial response. what should I do to get the complete response.
this is my code
#Override
protected JSONObject doInBackground(String... params) {
String path = null;
String response = null;
HashMap<String, String> request = null;
JSONObject requestJson = null;
DefaultHttpClient httpClient = null;
HttpPost httpPost = null;
StringEntity requestString = null;
ResponseHandler<String> responseHandler = null;
// get the email and password
try {
path = "http://xxxxxxxxxxxxxxxxxxx";
new URL(path);
} catch (MalformedURLException e) {
e.printStackTrace();
}
try {
// set the API request
request = new HashMap<String, String>();
request.put(new String("CetegoryCode"), "P");
request.entrySet().iterator();
// Store locations in JSON
requestJson = new JSONObject(request);
httpClient = new DefaultHttpClient();
httpPost = new HttpPost(path);
requestString = new StringEntity(requestJson.toString());
// sets the post request as the resulting string
httpPost.setEntity(requestString);
httpPost.setHeader("Content-type", "application/json");
// Handles the response
responseHandler = new BasicResponseHandler();
response = httpClient.execute(httpPost, responseHandler);
responseJson = new JSONObject(response);
} catch (Exception e) {
Log.e("Buffer Error", "Error converting result " + e.toString());
}
try {
responseJson = new JSONObject(response);
} catch (JSONException e) {
Log.e("JSON Parser", "Error parsing data " + e.toString());
}
return responseJson;
}
this is the image

If your response is returning JsonArray thn need to set tht response string jsonarray. create instance of jsonarray and fill it up with the response.
if its normal get ws thn you can append parameters in url like query string
protected Void doInBackground(String... urls) {
/************ Make Post Call To Web Server ***********/
BufferedReader reader = null;
try {
// Append parameters with values eg ?CetegoryCode=p
String path = "http://xxxxxxxxxxxxxxxxxxx?CetegoryCode=p";
URL url = new URL(path);
URLConnection conn = url.openConnection();
conn.setDoOutput(true);
OutputStreamWriter wr = new OutputStreamWriter(
conn.getOutputStream());
wr.write(data);
wr.flush();
// Get the server response
reader = new BufferedReader(new InputStreamReader(
conn.getInputStream()));
StringBuilder sb = new StringBuilder();
String line = null;
while ((line = reader.readLine()) != null) {
sb.append(line + "");
}
Content = sb.toString();
JSONArray jArray = new JSONArray(Content);
if (jArray != null)
Log.e("Data", "" + jArray.length());
} catch (Exception ex) {
Error = ex.getMessage();
} finally {
try {
reader.close();
}
catch (Exception ex) {
}
}
/*****************************************************/
return null;
}

Try out below code to parse and get JSON response:
public static JSONObject getJSONFromUrl(String url) {
// Making HTTP request
try {
URL url1 = new URL(url);
HttpURLConnection conn = (HttpURLConnection) url1.openConnection();
conn.setReadTimeout(10000 /* milliseconds */);
conn.setConnectTimeout(15000 /* milliseconds */);
conn.setRequestMethod("POST");
conn.setDoInput(true);
// Starts the query
conn.connect();
InputStream stream = conn.getInputStream();
json = convertStreamToString(stream);
stream.close();
} catch (Exception e) {
e.printStackTrace();
}
// try parse the string to a JSON object
try {
jObj = new JSONObject(json);
} catch (JSONException e) {
Log.e("JSON Parser", "Error parsing data " + e.toString());
}
// return JSON String
return jObj;
}
static String convertStreamToString(java.io.InputStream is) {
java.util.Scanner s = new java.util.Scanner(is).useDelimiter("\\A");
return s.hasNext() ? s.next() : "";
}
Use getJSONFromUrl method as below in your code:
#Override
protected JSONObject doInBackground(String... params) {
String path = null;
String response = null;
HashMap<String, String> request = null;
try {
responseJson = new JSONObject(response);
responseJson =getJSONFromUrl("http://xxxxxxxxxxxxxxxxxxx?CetegoryCode=p");
}catch (JSONException e) {
Log.e("JSON Parser", "Error parsing data " + e.toString());
}
return responseJson;
}

How to Decode String in Java or android?

I get Data from Json in android,date get and save in String Variable.but when use DecodeUrl its error:
Error: java.lang.IllegalArgumentException: Invalid % sequence at 40:
my code:
#SuppressLint("NewApi")
public String JsonReguest(String url) {
String json = "";
String result = "";
StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder()
.permitAll().build();
StrictMode.setThreadPolicy(policy);
HttpClient httpclient = new DefaultHttpClient();
// Prepare a request object
HttpGet httpget = new HttpGet(url);
httpget.setHeader("Accept", "application/json");
httpget.setHeader("Content-Type", "application/json");
HttpResponse response;
try {
response = httpclient.execute(httpget);
response.setHeader("Content-Type","UTF-8");
HttpEntity entity = response.getEntity();
if (entity != null) {
InputStream instream = entity.getContent();
result = convertStreamToString(instream);
InputStream stream = new ByteArrayInputStream(result.getBytes("UTF-8"));
result = convertStreamToString(stream);
// String encode_url=URLEncoder.encode(result,"UTF-8");
// String decode_url=URLDecoder.decode(encode_url,"UTF-8");
//result=decode_url;
//String decodedUrl = URLDecoder.decode(result, "UTF-8");
result=URLDecoder.decode(result);
}
} catch (Exception e) {
Log.e("Error", e.toString());
}
return result;
}
public static String convertStreamToString(InputStream is) {
BufferedReader reader = new BufferedReader(new InputStreamReader(is));
StringBuilder sb = new StringBuilder();
String line = null;
try {
while ((line = reader.readLine()) != null) {
sb.append(line + "\n");
}
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
is.close();
} catch (IOException e) {
e.printStackTrace();
}
}
return sb.toString();
}
simple text of json :
{"CategoryID":11,"ParentID":0,"Title":"%u062E%u0648%u062F%u0631%u0648","PicAddress":""},{"CategoryID":16,"ParentID":0,"Title":"%u0627%u0645%u0644%u0627%u0643%20","PicAddress":""}
this line crashed : result=URLDecoder.decode(result);
how to Resolve Problems.

first decode specifing your encoding
String result = URLDecoder.decode(url, "UTF-8");
and then go to http://json.org/, scroll down and choose one of the supported json parsing Java libraries

As Selvin commented %uxxxx is not a standard Url encoded string , so it's obvious to get an error
you have 2 options:
Contact the service provider to fix her url encoded strings and use URLDecoder.decode in your code
write a custom decoder for such strings
P.S. ask your questions more clear to avoid getting negative points

Illegal State Exception error: target host must not be null or set in parameters

I ran my app on my old galaxy s and it worked fine and then I my nexus s and it started giving me a few errors. I was getting an illegal character in path error in my JSONParser that I fixed by using URLEncoder.encode but now I am getting an illegal state exception error. I looked here http://blog.donnfelker.com/2010/04/29/android-odd-error-in-defaulthttpclient/
but I already had http:// in my url. I checked the debugger for the uri of my httpget. I am not exactly sure what I am looking for here. I know that I am trying to find if a character has been encoded that shouldn't have been as suggest in the comments of the article I linked to above but I am not sure how how to go about doing that. When I click on my uri under httpGet in the JSONParser.doInBackground method I get %5BLjava.lang.String%3B%4042b3f010. Am I correct that this is the encoded representation from the URLEncoder.encode? I pass in to my JSONParser.doInBackground a url of the type StringBuilder that I convert to String and then encode. The myURL entry in the debugger gives me the same as the uri: %5BLjava.lang.String%3B%4042b3f010. Am I going about doing this correctly. Thank for any help. These are what I believe to be the relevant parts of my code:
public class JSONParser extends AsyncTask<String, Void, JSONObject> {
static InputStream inputStream = null;
static JSONObject jObject = null;
static String jSon = "";
protected JSONObject doInBackground(String... url) {
// TODO Auto-generated method stub
//Make HTTP Request
try {
//defaultHttpClient
DefaultHttpClient httpClient = new DefaultHttpClient();
String myURL = url.toString();
myURL = URLEncoder.encode(myURL, "utf-8");
HttpGet httpGet = new HttpGet(myURL);
//header
httpGet.setHeader("Accept", "application/json");
HttpResponse httpResponse = httpClient.execute(httpGet);
HttpEntity httpEntity = httpResponse.getEntity();
inputStream = httpEntity.getContent();
} catch (UnsupportedEncodingException e){
e.printStackTrace();
} catch (ClientProtocolException e){
e.printStackTrace();
}catch (IOException e){
e.printStackTrace();
}
try {
BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream, "UTF-8"), 8);
StringBuilder stringBuilder = new StringBuilder();
String line = null;
while ((line = reader.readLine()) != null){
stringBuilder.append(line + "\n");
}
Log.d("JSON Contents", stringBuilder.toString());
inputStream.close();
jSon = stringBuilder.toString();
} catch (Exception e){
Log.e("Buffer Error", "Error converting result " + e.toString());
}
//try to parse the string to JSON Object
try {
jObject = new JSONObject(jSon);
} catch (JSONException e){
Log.e("JSON Parser", "Error parsing data " + e.toString());
}
//return JSON String
return jObject;
}
}
This is how I am building the url that I pass through to the parser:
public class getName {
static String nameOne = null;
static String nameTwo = null;
static StringBuilder personURLOne = new StringBuilder();
static StringBuilder personURLTwo = new StringBuilder();
public static String personURL = "http://api.themoviedb.org/3/search/person?api_key=bb0b6d66c2899aefb4d0863b0d37dc4e&query=";
public static StringBuilder getName1(EditText searchOne){
nameOne = searchOne.getText().toString();
nameOne = nameOne.replace(" ", "_");
personURLOne.append(personURL);
personURLOne = personURLOne.append(nameOne);
return personURLOne;
}
Appreciate any help
UPDATE - I changed my code to the following in my JSONParser:
public class JSONParser extends AsyncTask<String, Void, JSONObject> {
static InputStream inputStream = null;
static JSONObject jObject = null;
static String jSon = "";
public String myURL;
protected JSONObject doInBackground(String... url) {
// TODO Auto-generated method stub
//Make HTTP Request
try {
//defaultHttpClient
DefaultHttpClient httpClient = new DefaultHttpClient();
for(int i = 0; i < url.length; i++){
myURL = url[0];
myURL = URLEncoder.encode(myURL, "utf-8");
}
HttpGet httpGet = new HttpGet(myURL);

If you URL decode this %5BLjava.lang.String%3B%4042b3f010 you get [Ljava.lang.String;#42b3f010.
That's pretty suspicious, it's not a URL. When you call toString on an array, you get that funny looking string with an open bracket. For instance an array of ints prints out something like [I#33f42b49.
This is because url in your doInBackGround method is actually an array of Strings, not a String, because doInBackground takes a variable number of String parameters: doInBackground(String... That ellipses indicates a method with varags. So you don't want to call toString on it at all.
Instead you'll want to iterate over it and download all of them, or just take the first: url[0]. I'd rename it to urls too, just to make it obvious :)