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JSON sorting large data sets

http://openlibrary.org/search.json?q=prolog
I have the above API which i am going to be implementing in a android application.
Is there a way to grab from the json on the fly. a specific field for instance:
if i search the above i would need the Author, Language, suggested_title and ISBN. for each result. (so in the above case there would be 100 results.)
which i the plan on storing in a array in the format of
Title|author|lang|ISBN

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.URL;
public class main {
public static void main(String[] args) throws IOException
{
URL testing = new URL("http://openlibrary.org/search.json?q=prolog");
BufferedReader in = new BufferedReader(
new InputStreamReader(testing.openStream()));
String inputLine;
String test = null;
int i =1;
while ((inputLine = in.readLine()) != null)
{
if (inputLine == "\"title_suggest\":")
{
test = inputLine;
}
}
in.close();
System.out.println(test);
}
}
appears to work
as i could then add test to array location [x][y]

My HTML fetcher program in java returns incomplete results

My java code is:
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.ArrayList;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class celebGrepper {
static class CelebData {
URL link;
String name;
CelebData(URL link, String name) {
this.link=link;
this.name=name;
}
}
public static String grepper(String url) {
URL source;
String data = null;
try {
source = new URL(url);
HttpURLConnection connection = (HttpURLConnection) source.openConnection();
connection.connect();
InputStream is = connection.getInputStream();
/**
* Attempting to fetch an entire line at a time instead of just a character each time!
*/
StringBuilder str = new StringBuilder();
BufferedReader br = new BufferedReader(new InputStreamReader(is));
while((data = br.readLine()) != null)
str.append(data);
data=str.toString();
} catch (IOException e) {
e.printStackTrace();
}
return data;
}
public static ArrayList<CelebData> parser(String html) throws MalformedURLException {
ArrayList<CelebData> list = new ArrayList<CelebData>();
Pattern p = Pattern.compile("<td class=\"image\".*<img src=\"(.*?)\"[\\s\\S]*<td class=\"name\"><a.*?>([\\w\\s]+)<\\/a>");
Matcher m = p.matcher(html);
while(m.find()) {
CelebData current = new CelebData(new URL(m.group(1)),m.group(2));
list.add(current);
}
return list;
}
public static void main(String... args) throws MalformedURLException {
String html = grepper("https://www.forbes.com/celebrities/list/");
System.out.println("RAW Input: "+html);
System.out.println("Start Grepping...");
ArrayList<CelebData> celebList = parser(html);
for(CelebData item: celebList) {
System.out.println("Name:\t\t "+item.name);
System.out.println("Image URL:\t "+item.link+"\n");
}
System.out.println("Grepping Done!");
}
}
It's supposed to fetch the entire HTML content of https://www.forbes.com/celebrities/list/. However, when I compare the actual result below to the original page, I find the entire table that I need is missing! Is it because the page isn't completely loaded when I start getting the bytes from the page via the input stream? Please help me understand.
The Output of the page:
https://jsfiddle.net/e0771aLz/
What can I do to just extract the Image link and the names of the celebs?
I know it's an extremely bad practice to try to parse HTML using regex and is the stuff of nightmares, but on a certain video training course for android, that's exactly what the guy did, and I just wanna follow along since it's just in this one lesson.

How to listen to JSON file update using java

I create java program that load JSON file from url , I push json object to this url every 20 seconds I want the program to give notification when the JSON file updated here is my java code
package com.company;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import java.io.*;
import java.net.URL;
import java.nio.charset.Charset;
public class Main {
private static String readAll(Reader rd) throws IOException {
StringBuilder sb = new StringBuilder();
int cp;
while ((cp = rd.read()) != -1) {
sb.append((char) cp);
}
return sb.toString();
}
public static JSONArray readJsonFromUrl(String url) throws IOException, JSONException {
InputStream is = new URL(url).openStream();
try {
BufferedReader rd = new BufferedReader(new InputStreamReader(is, Charset.forName("UTF-8")));
String jsonText = readAll(rd);
JSONArray jsonArray = new JSONArray(jsonText);
return jsonArray;
} finally {
is.close();
}
}
public static void main(String[] args) throws IOException, JSONException {
JSONArray json = readJsonFromUrl("http://frozen-brook-16337.herokuapp.com/history.json");
for(int i=0;i<json.length();i++){
JSONObject jo=json.getJSONObject(i);
System.out.println(jo.get("data"));
}
}
}
How to make java program listen to JSON file update ?

You need to create a scheduler that executes your bit of code after every 20 seconds. There are multiple ways to achieve this.
A good robust way would be to use something like Quartz Scheduler
Or for a quick solution you can also create a Thread and have its run() method execute the code in a loop.
public class MyPush implements Runnable {
public void run() {
long twentySeconds = 20*1000L;
while(true) {
//execute your code
Thread.sleep(twentySeconds);
}
}
public static void main(String args[]) {
(new Thread(new MyPush())).start();
}
}

How to convert JSON object to XML in UTF-8 format

I am trying to convert a JSON object to an XML document.
Below is the code,noting that I want to output the XML in UTF-8 format.
package com.test.json;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import org.json.JSONObject;
import org.json.XML;
public class ConvertJSONtoXML {
public static void main(String[] args) throws Exception {
BufferedReader jsonBuffer = new BufferedReader(new FileReader(new File("C:\\Users\\test\\Desktop\\sample-json.json")));
String line = null;
String json="";
while( (line=jsonBuffer.readLine())!=null){
json+=line; // here we have all json loaded
}
JSONObject jsonObject = new JSONObject(json);
System.out.println(XML.toString(jsonObject)); // here we have XML Code
jsonBuffer.close();
}
}
Can anyone please help on this. I have JSON data in Thai character.

Update your class to use an InputStreamReader instead of FileReader because InputStreamReaders can take the encoding charset as a second constructor argument:
public class ConvertJSONtoXML
{
public static void main(String[] args) throws Exception
{
File jsonFile = new File("C:\\Users\\test\\Desktop\\sample-json.json");
InputStreamReader reader = new InputStreamReader(new FileInputStream(jsonFile), "UTF-8");
BufferedReader jsonBuffer = new BufferedReader(reader);
String line;
StringBuilder json = new StringBuilder();
while ((line = jsonBuffer.readLine()) != null)
{
json.append(line); // here we have all json loaded
}
JSONObject jsonObject = new JSONObject(json.toString());
System.out.println(XML.toString(jsonObject)); // here we have XML Code
jsonBuffer.close();
}
}
The code has been also updated to use a StringBuilder for json tokens concatenation.

Parsing the web page response as Json, in Java

I have a java code:
URL oracle = new URL("https://x.x.x.x.x.x.-001");
System.out.println(oracle.openStream());
BufferedReader in = new BufferedReader(new InputStreamReader(oracle.openStream()));
String inputLine;
while ((inputLine = in.readLine()) != null)
System.out.println(inputLine);
Which is opening the connection and printing the contents of it. The contents are indeed Json. The output is something like:
{
"merchantId": "guest",
"txnId": "guest-1349269250-001",
}
I wish to parse this in json simple jar. I changed the code loop like this:
JSONObject obj = new JSONObject();
while ((inputLine = in.readLine()) != null)
obj.put("Result",inputLine);
But that doesn't seem to be working. The output I'm getting is:
{"Result":"}"}

You should use the JSONParser#Parse() method or the JSONValue#parse() method :
URL oracle = new URL("https://x.x.x.x.x.x.-001");
System.out.println(oracle.openStream());
Reader in = new InputStreamReader(oracle.openStream());
Object json = JSONValue.parse(in);

Are you sure you're following the documentation on how to parse a JSON string?
By the looks of it you have to obtain the entire string and call a JSONParse#parse() on it, but your code is filling up a HashMap (JSONObject's parent class) with each of the lines of the JSON. In fact it stores just the last line because you're calling put() with the same "Result" key on every iteration.

You should read whole contents to String variable first and parse it to json. Be careful of ""(double quote). Java uses \" for double quote. Like.
import java.io.BufferedReader;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import org.json.simple.JSONObject;
import org.json.simple.parser.JSONParser;
import org.json.simple.parser.ParseException;
public class JsonSimpleExample3 {
public static void main(String args[]) {
JSONParser parser = new JSONParser();
//String str = "{\"merchantId\": \"guest\",\"txnId\": \"guest-1349269250-001\",}";
//intilize an InputStream
InputStream is = new ByteArrayInputStream("file content".getBytes());
//read it with BufferedReader and create string
BufferedReader br = new BufferedReader(new InputStreamReader(is));// Instead of is, you should use oracle.openStream()
StringBuilder sb = new StringBuilder();
String line;
try {
while ((line = br.readLine()) != null) {
sb.append(line);
}
} catch (IOException e1) {
e1.printStackTrace();
}
// parse string
try {
JSONObject jsonObject = (JSONObject) parser.parse(sb.toString());
String merchantId = (String) jsonObject.get("merchantId");
System.out.println(merchantId);
String txnId = (String) jsonObject.get("txnId");
System.out.println(txnId);
} catch (ParseException e) {
e.printStackTrace();
}
}
}

try this link its really helpful if you are going to be logging in or staff like that
Java Json simple
import java.io.IOException;
import java.net.URL;
import org.apache.commons.io.IOUtils;
import org.json.simple.JSONArray;
import org.json.simple.JSONObject;
import org.json.simple.JSONValue;
import org.json.simple.parser.ParseException;
public class ParseJson1 {
public static void main(String[] args) {
String url = "http://freemusicarchive.org/api/get/genres.json?api_key=60BLHNQCAOUFPIBZ&limit=2";
/*
* {"title":"Free Music Archive - Genres","message":"","errors":[],"total" : "161","total_pages":81,"page":1,"limit":"2",
* "dataset":
* [{"genre_id": "1","genre_parent_id":"38","genre_title":"Avant-Garde" ,"genre_handle": "Avant-Garde","genre_color":"#006666"},
* {"genre_id":"2","genre_parent_id" :null,"genre_title":"International","genre_handle":"International","genre_color":"#CC3300"}]}
*/
try {
String genreJson = IOUtils.toString(new URL(url));
JSONObject genreJsonObject = (JSONObject) JSONValue.parseWithException(genreJson);
// get the title
System.out.println(genreJsonObject.get("title"));
// get the data
JSONArray genreArray = (JSONArray) genreJsonObject.get("dataset");
// get the first genre
JSONObject firstGenre = (JSONObject) genreArray.get(0);
System.out.println(firstGenre.get("genre_title"));
} catch (IOException | ParseException e) {
e.printStackTrace();
}
}
}