This question already has answers here:
Converting JSON data to Java object
(14 answers)
Closed 6 years ago.
Here is what I have so far:
public Bitmap getAlbumCover(Context context, String song, String artist) {
this.context = context;
song = song.replace(" ", "%20");
artist = artist.replace(" ", "%20");
try {
conn = new URL("https://api.spotify.com/v1/search?q=track" + song + ":%20artist:" + artist + "&type=track)").openConnection();
} catch (IOException e) {
e.printStackTrace();
}
if (conn != null)
conn.setDoOutput(true);
try {
reader = new BufferedReader(new InputStreamReader(conn.getInputStream()));
} catch (IOException e) {
e.printStackTrace();
}
if (reader != null) {
// Read Server Response
String line2 = null;
try {
while ((line2 = reader.readLine()) != null) {
sb.append(line2);
}
} catch (IOException e) {
e.printStackTrace();
}
try {
json = new JSONArray(sb.toString());
} catch (JSONException e) {
e.printStackTrace();
}
}
JSONParser parser= new JSONParser();
try {
JSONObject jsonObject = (JSONObject) parser.parse(reader);
try {
array = (JSONArray) jsonObject.get("items");
} catch (JSONException e) {
e.printStackTrace();
}
// take each value from the json array separately
} catch (IOException e) {
e.printStackTrace();
} catch (ParseException e) {
e.printStackTrace();
}
return null;
}
The JSON I am using is located here:
https://api.spotify.com/v1/search?q=track:Ready%20To%20Fall%20artist:rise%20against%20&type=track
I am trying to get the image url located in the images array and the preview_track url located in items.
I use Jackson library to parse JSON to java opbject.
if you create your java object with the same structure as JSON this can be done using this:
ObjectMapper mapper = new ObjectMapper();
mapper.readValue(jsonUrl, YourClass.class);
So your OBJECT will have tracks and then tracks will have object album and album will have object other details. Just structure it as the JSON is and you are there.
Related
I'm using volley to get a file from the internet, the file is an array. I'm saving the file in cache to do this I have to convert the file into a string. I have a function that reads the cache and pass the response to another file to display
the information, but when i'm trying to convert the resoionse back to an array i get an error
Value AuthStatus of type java.lang.String cannot be converted to JSONObject
I'm really new on android, hoping someone can point me on the right direction
private void cacheFile(JSONObject response) {
JSONObject res = response;
String filename = "jsonfile";
FileOutputStream outputStream;
try {
outputStream = openFileOutput(filename, Context.MODE_PRIVATE);
outputStream.write(res.toString().getBytes("utf-8"));
outputStream.close();
Log.e(TAG, "Bien");
} catch (Exception e) {
e.printStackTrace();
}
}
private void readCache(String filename) {
FileInputStream inputStream;
try {
inputStream = openFileInput(filename);
inputStream.read();
String body = IOUtils.toString(inputStream, StandardCharsets.UTF_8.name());
inputStream.close();
fromCache(body);
} catch (Exception e) {
e.printStackTrace();
}
}
public void fromCache(String json) {
JSONObject jsonObject = null;
try {
jsonObject = new JSONObject(json);
JSONArray jsonArray = jsonObject.getJSONArray("cars");
Log.e(TAG, "Array Size: " + jsonArray.length());
} catch (JSONException e) {
e.printStackTrace();
}
}
You have to use JSONValue.parse method as shown below:
public void fromCache(String json) {
JSONObject jsonObject = null;
try {
jsonObject = (JSONObject)JSONValue.parse(json);
JSONArray jsonArray = jsonObject.getJSONArray("cars");
Log.e(TAG, "Array Size: " + jsonArray.length());
} catch (JSONException e) {
e.printStackTrace();
}
}
I am trying to extract values from JSON from the URL provided below using GSON java library:
http://api.wunderground.com/api/b28d047ca410515a/forecast/q/-33.912,151.013.json
I have successfully used the code provided below to extract data from URL below:
http://api.wunderground.com/api/b28d047ca410515a/conditions/q/-33.912,151.013.json
Code:
String url = "http://api.wunderground.com/api/b28d047ca410515a/conditions/q/-33.912,151.013.json";
String url2 = "http://api.wunderground.com/api/b28d047ca410515a/forecast/q/-33.912,151.013.json";
InputStream is = null;
try {
is = new URL(url).openStream();
BufferedReader rd = new BufferedReader(new InputStreamReader(is, Charset.forName("UTF-8")));
String jsonText = readAll(rd);
JsonElement je = new JsonParser().parse(jsonText);
System.out.println("Current Temperature:" + getAtPath(je, "current_observation/temp_c").getAsString() );
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
if (is != null)
is.close();
} catch (IOException e) {
e.printStackTrace();
}
}
However I am getting exception trying to extract from url2 as per code below , it seems to be a more complicated json to get values from, any help please?
// below code not working
weather_icon_url = getAtPath(je, "current_observation/icon_url").getAsString();
is = new URL(url2).openStream();
BufferedReader rd2 = new BufferedReader(new InputStreamReader(is, Charset.forName("UTF-8")));
String jsonText2 = readAll(rd2);
JsonElement je2 = new JsonParser().parse(jsonText2);
System.out.println("max Temperature:" + getAtPath(je2, "forecast/simpleforecast/forecastday/high/celsius").getAsString() );
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
if (is != null)
is.close();
} catch (IOException e) {
e.printStackTrace();
}
}
getAtPath code:
private static JsonElement getAtPath(JsonElement e, String path) {
JsonElement current = e;
String ss[] = path.split("/");
for (int i = 0; i < ss.length; i++) {
current = current.getAsJsonObject().get(ss[i]);
}
return current;
}
The problem you are facing is because there is an issue with the getAtPath implementation.
[{"date":{"epoch":"1459152000"... represents a JSONArray which the method is trying to access as JSONObject. Hence the IllegalStateException.
JsonObject com.google.gson.JsonElement.getAsJsonObject()
convenience method to get this element as a JsonObject. If the element
is of some other type, a IllegalStateException will result. Hence it
is best to use this method after ensuring that this element is of the
desired type by calling isJsonObject() first.
You can update and use something like below, as of now it returns only the first element.
private static JsonElement getAtPath(JsonElement e, String path) {
JsonElement current = e;
String ss[] = path.split("/");
for (int i = 0; i < ss.length; i++) {
if(current instanceof JsonObject){
current = current.getAsJsonObject().get(ss[i]);
} else if(current instanceof JsonArray){
JsonElement jsonElement = current.getAsJsonArray().get(0);
current = jsonElement.getAsJsonObject().get(ss[i]);
}
}
return current;
}
This should work:
System.out.println("max Temperature:" + getAtPath(je2, "forecast/simpleforecast/forecastday/high/celsius").getAsString() );
It's my first post here.
Well, I got a problem trying to write nested JSON into File in Android.
It show me a java.lang.StackOverflowError.
My question is: Is there any way to write a nested JSON into file without having any kind of problem with stack.
I'll show you nested JSON and the way I'm trying to write into the File
JSONObject fingerPrint = new JSONObject();
try {
fingerPrint.put("fingerPrint", fingerPrint);
} catch (JSONException e) {
Log.v(TAG, "Error parsing creating JSON \"fingerPrint\"");
e.printStackTrace();
}
JSONObject fingerPrintMaterial = new JSONObject();
try {
fingerPrintMaterial.put("methodType", FingerprintFacade.MAC_SHA256);
fingerPrintMaterial.put("keySize", 5);
} catch (JSONException e) {
Log.v(TAG, "Error parsing creating JSON \"fingerPrintMaterial\"");
e.printStackTrace();
}
JSONObject userFingerPrint = new JSONObject();
try {
userFingerPrint.put("fingerPrint", fingerPrint);
userFingerPrint.put("fingerPrintMaterial", fingerPrintMaterial);
} catch (JSONException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
Now this is the way I'm trying to write:
try {
BufferedWriter file=new BufferedWriter(new FileWriter(pathToNonEncryptedTxt+filename, true));
//FileWriter file = new FileWriter(pathToNonEncryptedTxt+filename);
file.write(userDigitalContent.toString(2));
file.newLine();
file.write(userFingerPrint.toString(2));
file.flush();
file.close();
} catch (IOException e) {
Log.v(TAG, "Error saving JSON into "+filename);
e.printStackTrace();
} catch (JSONException e) {
Log.v(TAG, "Error saving JSON into "+filename);
e.printStackTrace();
}
Oh!! BTW, I need to output something like that into a .txt File:
{
"userFingerPrint": {
"fingerPrint": {
"fingerPrint": "fingerPrintValue"
},
"fingerPrintMaterial": {
"methodType": "methodTypeValue",
"keySize": "5"
}
}
I guess there is some thing wrong in creating JSONObject in your code. Refer this tutorial for creating JSONObject once you create JSONObject you can get Sting from JSONObject by calling jsonObj.toString() and write that string to file
I'm trying to use JSON-Simple to read a configuration file that's in JSON using the following code
File f = new File("config.json");
JSONParser parser = new JSONParser();
try {
int i;
StringBuilder out = new StringBuilder();
FileReader reader = new FileReader(f);
while ((i = reader.read()) != -1) {
out.append((char) i);
}
JSONArray array = (JSONArray) JSONValue.parse(out.toString());
} catch (Exception e) {
System.out.println(e.toString());
}
or
File f = new File("config.json");
JSONParser parser = new JSONParser();
try {
Object obj = parser.parse(new FileReader(f));
JSONObject jsonObject = (JSONObject) obj;
JSONArray array = (JSONArray) jsonObject.get("module");
Iterator<String> itreator = array.iterator();
while (itreator.hasNext()) {
System.out.println(itreator.next());
}
} catch (FileNotFoundException fnf) {
fnf.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (ParseException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
but both are returning the error
org.json.simple.JSONObject cannot be cast to org.json.simple.JSONArray
however when doing
File f = new File("config.json");
try {
System.out.println(JSONValue.parse(new FileReader(f)));
} catch (Exception e) {
System.out.println(e.toString());
}
it returns the file's contents.
The config file can be seen here:
http://pastebin.com/5xJTHSwj
module tag in your config file isn't array. JSON array starts with [
e.g.
"module" : [{prop : "One"},{prop : "Two"}]
Use this code instead
JSONObject moduleObject= (JSONObject ) jsonObject.get("module");
I need to update a value in my JSON file using java but somehow I am unable to.Following is my JSON format which I am trying to parse
{
"recentActivities":[
{
"displayValue":"POC | Augmented Reality",
"link":"poc.jsp?search=augmented%20reality",
"timestamp":"18/07/2013 17:33"
},
{
"displayValue":"POC | Image Editing in Hybrid Application",
"link":"poc.jsp?search=image%20editing",
"timestamp":"18/07/2013 01:00"
}
],
"lastEmailSent": "29/06/2013 00:00"
}
I need to update lastEmailSent to current date but somehow I am getting stuck. Below is my java code which i am using
private void updateLastEmailTimeStamp(String jsonFilePath) {
JSONParser parser = new JSONParser();
JSONObject jsonObject = new JSONObject();
JSONObject lastEmailTimeStamp = new JSONObject();
FileReader reader =null;
try {
File jsonFile = new File(jsonFilePath);
reader = new FileReader(jsonFile);
jsonObject = (JSONObject) parser.parse(reader);
lastEmailTimeStamp = (JSONObject) jsonObject.get("lastEmailSent");
//write current date as last mail sent time.
writeTimeStamp(lastEmailTimeStamp, jsonFile);
APP_LOGGER.info("last Email Sent timestamp updated");
} catch (IOException ex) {
APP_LOGGER.error(ex.getLocalizedMessage(), ex);
} catch (ParseException ex) {
APP_LOGGER.error(ex.getLocalizedMessage(), ex);
}
}
private void writeTimeStamp(JSONObject lastEmailTimeStamp, File jsonFile) {
FileWriter writer = null;
try{
writer = new FileWriter(jsonFile);
String currentDate = MyDateFormatterUtility.formatDate(new Date(),"dd/MM/yyyy HH:mm");
lastEmailTimeStamp.put(SubscriptionConstants.LAST_EMAIL_TIMESTAMP, currentDate);
writer.write(lastEmailTimeStamp.toJSONString());
}catch(IOException ex){
APP_LOGGER.error(ex.getLocalizedMessage(), ex);
}finally{
try {
writer.flush();
writer.close();
} catch (IOException ex) {
APP_LOGGER.error(ex.getLocalizedMessage(), ex);
}
}
}
I am getting error in the following line
lastEmailTimeStamp = (JSONObject) jsonObject.get("lastEmailSent");.
I guess I am not correctly parsing or accessing the object. Can somebody please make me correct?
Thank you!
I agree with #Hot Licks, but you can try fixing it by doing:
String lastEmailSent = jsonObject.getString("lastEmailSent");
Also, if that isn't the problem, it may be that the text coming from your file is not exactly the JSON text you posted here. In which case, you can read the file into a string, add a breakpoint and check the string to see if it has all the JSON elements you expect it to.
In Java 7 you can read the text in like:
String content = readFile(jsonFilePath, Charset.defaultCharset());
static String readFile(String path, Charset encoding)
throws IOException
{
byte[] encoded = Files.readAllBytes(Paths.get(path));
return encoding.decode(ByteBuffer.wrap(encoded)).toString();
}
Finally, i was able to figure out the solution. Following changes were needed in the code
private void updateLastEmailTimeStamp(String jsonFilePath) {
JSONParser parser = new JSONParser();
JSONObject jsonObject = new JSONObject();
FileReader reader =null;
try {
File jsonFile = new File(jsonFilePath);
reader = new FileReader(jsonFile);
jsonObject = (JSONObject) parser.parse(reader);
jsonObject.remove("lastEmailSent");
//write current date as last mail sent time.
writeTimeStamp(jsonObject, jsonFile);
APP_LOGGER.info("last Email Sent timestamp updated");
} catch (IOException ex) {
APP_LOGGER.error(ex.getLocalizedMessage(), ex);
} catch (ParseException ex) {
APP_LOGGER.error(ex.getLocalizedMessage(), ex);
} catch (RuntimeException e) {
e.printStackTrace();
}catch (Exception e) {
e.printStackTrace();
}
}
/**
* Method to write current date as last mail sent timestamp
* denoting when the newsletter was sent last.
*
* #param jsonObj- date for last email sent.
* #param jsonFile - recentactivities.json file
*/
#SuppressWarnings("unchecked")
private void writeTimeStamp(JSONObject jsonObj, File jsonFile) {
FileWriter writer = null;
try {
writer = new FileWriter(jsonFile);
String currentDate = MyDateFormatter.formatDate(new Date(),"dd/MM/yyyy HH:mm");
jsonObj.put("lastEmailSent", currentDate);
writer.write(jsonObj.toJSONString());
}catch(IOException ex){
APP_LOGGER.error(ex.getLocalizedMessage(), ex);
}finally{
try {
writer.flush();
writer.close();
} catch (IOException ex) {
APP_LOGGER.error(ex.getLocalizedMessage(), ex);
}
}
}