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Getting specific element in Json respone without using an external libary

I want to create a GitHub update checker which provides the version of the newest release.
public static void main(String[] args) {
HttpURLConnection httpURLConnection = null;
try {
httpURLConnection = (HttpURLConnection) new URL("https://api.github.com/repos/MilkBowl/Vault/releases/latest").openConnection();
httpURLConnection.setRequestMethod("GET");
httpURLConnection.setRequestProperty("Content-Type", "application/json");
try (final InputStream inputStream = httpURLConnection.getInputStream(); final InputStreamReader inputStreamReader = new InputStreamReader(inputStream); final BufferedReader bufferedReader = new BufferedReader(inputStreamReader)) {
}
} catch (final IOException exception) {
exception.printStackTrace();
} finally {
if (httpURLConnection != null) {
httpURLConnection.disconnect();
}
}
}
This is what I got so far. It returns this Json response:
https://api.github.com/repos/MilkBowl/Vault/releases/latest
Now I want to get the "tag_name". How can I do this with plain Java? I do not want to use an external library.

O well i don't have reputation enough to comment, so...
I think you can use regex to grab only the name, you can use something like this:
name.+?,
And after that apply some replaces for sanitization.
Something like that:
Pattern.compile("'name.+?,'").matcher(your data);
if (matcher.find()){
System.out.println(matcher.group(1).replace("\"name\": \"", "").replace("\",", "");
}

How to pass and read string from android to sql using JSON

Previously, i can access the string from php remotely. I find it difficult at first but AsyncTask did the work for me. Now, i can access the result of the query from php to sql server. But I would like to pass a string from my java class to php and as I googled some information, i saw some JSON post and get codes but i can't clearly understand them. Here's my code:
protected String doInBackground(Void... params) {
BufferedReader br = null;
StringBuilder sb = new StringBuilder();
String url = "http://122.2.8.226/MITBookstore/sqlconnect.php";
HttpURLConnection urlConnection = null;
String line;
try {
urlConnection = (HttpURLConnection) new URL(url).openConnection();
InputStream in = urlConnection.getInputStream();
br = new BufferedReader(new InputStreamReader(in));
while ((line = br.readLine()) != null) {
sb.append(line);
}
}
catch (Exception e) {
e.printStackTrace();
}
finally {
if (br != null) {
try {
br.close();
} catch (Exception e) {
e.printStackTrace();
}
}
}
return sb.toString();
The string is contained in "sb.toString()". Now how would I add a JSON something in my code to send string from java to php, and also get the result string from php to java as well. Thanks in advance for any help.

If you receive response as JSON format from server, make the json string to JSONObject first. And then read the json data for your use.
try {
JSONObject obj = new JSONObject(sb.toString()); // make string to json obj
Iterator iter = obj.keys(); // get all keys from json obj and iterating
while(iter.hasNext()){
String key = (String)iter.next();
String str = obj.get(key).toString();
// write your code
}
} catch(Exception e) {
e.printStackTrace();
}
Your code already contains the answer of your question. After make url connection, just add parameter for sending your data to server with OutputStreamWriter as like you did for receive the response with InpustStreamReader.
BufferedReader br = null;
StringBuilder sb = new StringBuilder();
String url = "http://122.2.8.226/MITBookstore/sqlconnect.php";
HttpURLConnection urlConnection = null;
String line;
try {
urlConnection = (HttpURLConnection) new URL(url).openConnection();
// wrtie params
OutputStreamWriter we = new OutputStreamWriter(urlConnection.getOutPutStream());
wr.write(data); // data (make json obj to 'key=value' string)
wr.flush();
wr.close();
// read response
InputStream in = urlConnection.getInputStream();
br = new BufferedReader(new InputStreamReader(in));
while ((line = br.readLine()) != null) {
sb.append(line);
}
}
catch (Exception e) {
e.printStackTrace();
}
finally {
if (br != null) {
try {
br.close();
} catch (Exception e) {
e.printStackTrace();
}
}
}enter code here

Java, FileNotfound Exception, While reading conn.getInputStream()

Please tell me some one, How to resolve this problem,
Sometime I am getting Filenotfound Exception and Some time this code working fine.
Below is my code,
public String sendSMS(String data, String url1) {
URL url;
String status = "Somthing wrong ";
try {
url = new URL(url1);
URLConnection conn = url.openConnection();
conn.setDoOutput(true);
conn.setRequestProperty("User-Agent","Mozilla/5.0 ( compatible ) ");
conn.setRequestProperty("Accept","*/*");
OutputStreamWriter wr = new OutputStreamWriter(conn.getOutputStream());
wr.write(data);
wr.flush();
// Get the response
try {
BufferedReader rd = new BufferedReader(new InputStreamReader(conn.getInputStream()));
String s;
while ((s = rd.readLine()) != null) {
status = s;
}
rd.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
}
wr.close();
} catch (MalformedURLException e) {
status = "MalformedURLException Exception in sendSMS";
e.printStackTrace();
} catch (IOException e) {
status = "IO Exception in sendSMS";
e.printStackTrace();
}
return status;
}

Rewrite like this and let me know how you go... (note closing of reading and writing streams, also the cleanup of streams if an exception is thrown).
public String sendSMS(String data, String url1) {
URL url;
OutputStreamWriter wr = null;
BufferedReader rd = null;
String status = "Somthing wrong ";
try {
url = new URL(url1);
URLConnection conn = url.openConnection();
conn.setDoOutput(true);
conn.setRequestProperty("User-Agent","Mozilla/5.0 ( compatible ) ");
conn.setRequestProperty("Accept","*/*");
wr = new OutputStreamWriter(conn.getOutputStream());
wr.write(data);
wr.flush();
wr.close();
rd = new BufferedReader(new InputStreamReader(conn.getInputStream()));
String s;
while ((s = rd.readLine()) != null) {
status = s;
}
rd.close();
} catch (Exception e) {
if (wr != null) try { wr.close(); } catch (Exception x) {/*cleanup*/}
if (rd != null) try { rd.close(); } catch (Exception x) {/*cleanup*/}
e.printStackTrace();
}
return status;
}

This issue seems to be known, but for different reasons so its not clear why this happend.
Some threads would recommend closing the OutputStreamWriter as flushing it is not enough, therefor i would try to clos it directly after fushing as you are not using it in the code between the flush and close.
Other threads show that using a different connections like HttpURLConnection are avoiding this problem from occuring (Take a look here)
Another article suggests to use the URLEncoder class’ static method encode. This method takes a string and encodes it to a string that is ok to put in a URL.
Some similar questions:
URL is accessable with browser but still FileNotFoundException with URLConnection
URLConnection FileNotFoundException for non-standard HTTP port sources
URLConnection throwing FileNotFoundException
Wish you good luck.

It returns FileNotFoundException when the server response to HTTP request is code 404.
Check your URL.

Java code for using google custom search API

Can anyone please share some java codes for getting started with google search api's.I searched on Internet but not found any proper documentation or good sample codes.The codes which I found doesn't seem to be working.I'll be thankful if anyone can help me.(I have obtained API key and custom search engine id).
Thanks.

I have changed the while loop in the code provided by #Zakaria above. It might not be a proper way of working it out but it gives you the result links of google search. You just need to parse the output. See here,
public static void main(String[] args) throws Exception {
String key="YOUR KEY";
String qry="Android";
URL url = new URL(
"https://www.googleapis.com/customsearch/v1?key="+key+ "&cx=013036536707430787589:_pqjad5hr1a&q="+ qry + "&alt=json");
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setRequestMethod("GET");
conn.setRequestProperty("Accept", "application/json");
BufferedReader br = new BufferedReader(new InputStreamReader(
(conn.getInputStream())));
String output;
System.out.println("Output from Server .... \n");
while ((output = br.readLine()) != null) {
if(output.contains("\"link\": \"")){
String link=output.substring(output.indexOf("\"link\": \"")+("\"link\": \"").length(), output.indexOf("\","));
System.out.println(link); //Will print the google search links
}
}
conn.disconnect();
}
Hope it works for you too.

For anyone who would need working example of Custom search API using Google library, you can use this method:
public static List<Result> search(String keyword){
Customsearch customsearch= null;
try {
customsearch = new Customsearch(new NetHttpTransport(),new JacksonFactory(), new HttpRequestInitializer() {
public void initialize(HttpRequest httpRequest) {
try {
// set connect and read timeouts
httpRequest.setConnectTimeout(HTTP_REQUEST_TIMEOUT);
httpRequest.setReadTimeout(HTTP_REQUEST_TIMEOUT);
} catch (Exception ex) {
ex.printStackTrace();
}
}
});
} catch (Exception e) {
e.printStackTrace();
}
List<Result> resultList=null;
try {
Customsearch.Cse.List list=customsearch.cse().list(keyword);
list.setKey(GOOGLE_API_KEY);
list.setCx(SEARCH_ENGINE_ID);
Search results=list.execute();
resultList=results.getItems();
}
catch ( Exception e) {
e.printStackTrace();
}
return resultList;
}
This method returns List of Result objects, so you can iterate through it
List<Result> results = new ArrayList<>();
try {
results = search(QUERY);
} catch (Exception e) {
e.printStackTrace();
}
for(Result result : results){
System.out.println(result.getDisplayLink());
System.out.println(result.getTitle());
// all attributes:
System.out.println(result.toString());
}
As you have noticed, you have to define your custom GOOGLE_API_KEY, SEARCH_ENGINE_ID, QUERY and HTTP_REQUEST_TIMEOUT, ie
private static final int HTTP_REQUEST_TIMEOUT = 3 * 600000;
I use gradle dependencies:
dependencies {
compile 'com.google.apis:google-api-services-customsearch:v1-rev57-1.23.0'
}

Well, I think that there is nothing special in the sense that you can use a Java RESTFUL client.
I tried the Custom API using that Java code and basing on the Google documentation :
public static void main(String[] args) throws IOException {
URL url = new URL(
"https://www.googleapis.com/customsearch/v1?key=YOUR-KEY&cx=013036536707430787589:_pqjad5hr1a&q=flowers&alt=json");
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setRequestMethod("GET");
conn.setRequestProperty("Accept", "application/json");
BufferedReader br = new BufferedReader(new InputStreamReader(
(conn.getInputStream())));
String output;
System.out.println("Output from Server .... \n");
while ((output = br.readLine()) != null) {
System.out.println(output);
}
conn.disconnect();
}
You have to replace "YOUR-KEY" with a one found on the Google APIs Console.

Read url to string in few lines of java code

I'm trying to find Java's equivalent to Groovy's:
String content = "http://www.google.com".toURL().getText();
I want to read content from a URL into string. I don't want to pollute my code with buffered streams and loops for such a simple task. I looked into apache's HttpClient but I also don't see a one or two line implementation.

Now that some time has passed since the original answer was accepted, there's a better approach:
String out = new Scanner(new URL("http://www.google.com").openStream(), "UTF-8").useDelimiter("\\A").next();
If you want a slightly fuller implementation, which is not a single line, do this:
public static String readStringFromURL(String requestURL) throws IOException
{
try (Scanner scanner = new Scanner(new URL(requestURL).openStream(),
StandardCharsets.UTF_8.toString()))
{
scanner.useDelimiter("\\A");
return scanner.hasNext() ? scanner.next() : "";
}
}

This answer refers to an older version of Java. You may want to look at ccleve's answer.
Here is the traditional way to do this:
import java.net.*;
import java.io.*;
public class URLConnectionReader {
public static String getText(String url) throws Exception {
URL website = new URL(url);
URLConnection connection = website.openConnection();
BufferedReader in = new BufferedReader(
new InputStreamReader(
connection.getInputStream()));
StringBuilder response = new StringBuilder();
String inputLine;
while ((inputLine = in.readLine()) != null)
response.append(inputLine);
in.close();
return response.toString();
}
public static void main(String[] args) throws Exception {
String content = URLConnectionReader.getText(args[0]);
System.out.println(content);
}
}
As #extraneon has suggested, ioutils allows you to do this in a very eloquent way that's still in the Java spirit:
InputStream in = new URL( "http://jakarta.apache.org" ).openStream();
try {
System.out.println( IOUtils.toString( in ) );
} finally {
IOUtils.closeQuietly(in);
}

Or just use Apache Commons IOUtils.toString(URL url), or the variant that also accepts an encoding parameter.

There's an even better way as of Java 9:
URL u = new URL("http://www.example.com/");
try (InputStream in = u.openStream()) {
return new String(in.readAllBytes(), StandardCharsets.UTF_8);
}
Like the original groovy example, this assumes that the content is UTF-8 encoded. (If you need something more clever than that, you need to create a URLConnection and use it to figure out the encoding.)

Now that more time has passed, here's a way to do it in Java 8:
URLConnection conn = url.openConnection();
try (BufferedReader reader = new BufferedReader(new InputStreamReader(conn.getInputStream(), StandardCharsets.UTF_8))) {
pageText = reader.lines().collect(Collectors.joining("\n"));
}

Additional example using Guava:
URL xmlData = ...
String data = Resources.toString(xmlData, Charsets.UTF_8);

Java 11+:
URI uri = URI.create("http://www.google.com");
HttpRequest request = HttpRequest.newBuilder(uri).build();
String content = HttpClient.newHttpClient().send(request, BodyHandlers.ofString()).body();

If you have the input stream (see Joe's answer) also consider ioutils.toString( inputstream ).
http://commons.apache.org/io/api-1.4/org/apache/commons/io/IOUtils.html#toString(java.io.InputStream)

The following works with Java 7/8, secure urls, and shows how to add a cookie to your request as well. Note this is mostly a direct copy of this other great answer on this page, but added the cookie example, and clarification in that it works with secure urls as well ;-)
If you need to connect to a server with an invalid certificate or self signed certificate, this will throw security errors unless you import the certificate. If you need this functionality, you could consider the approach detailed in this answer to this related question on StackOverflow.
Example
String result = getUrlAsString("https://www.google.com");
System.out.println(result);
outputs
<!doctype html><html itemscope="" .... etc
Code
import java.net.URL;
import java.net.URLConnection;
import java.io.BufferedReader;
import java.io.InputStreamReader;
public static String getUrlAsString(String url)
{
try
{
URL urlObj = new URL(url);
URLConnection con = urlObj.openConnection();
con.setDoOutput(true); // we want the response
con.setRequestProperty("Cookie", "myCookie=test123");
con.connect();
BufferedReader in = new BufferedReader(new InputStreamReader(con.getInputStream()));
StringBuilder response = new StringBuilder();
String inputLine;
String newLine = System.getProperty("line.separator");
while ((inputLine = in.readLine()) != null)
{
response.append(inputLine + newLine);
}
in.close();
return response.toString();
}
catch (Exception e)
{
throw new RuntimeException(e);
}
}

Here's Jeanne's lovely answer, but wrapped in a tidy function for muppets like me:
private static String getUrl(String aUrl) throws MalformedURLException, IOException
{
String urlData = "";
URL urlObj = new URL(aUrl);
URLConnection conn = urlObj.openConnection();
try (BufferedReader reader = new BufferedReader(new InputStreamReader(conn.getInputStream(), StandardCharsets.UTF_8)))
{
urlData = reader.lines().collect(Collectors.joining("\n"));
}
return urlData;
}

URL to String in pure Java
Example call to get payload from http get call
String str = getStringFromUrl("YourUrl");
Implementation
You can use the method described in this answer, on How to read URL to an InputStream and combine it with this answer on How to read InputStream to String.
The outcome will be something like
public String getStringFromUrl(URL url) throws IOException {
return inputStreamToString(urlToInputStream(url,null));
}
public String inputStreamToString(InputStream inputStream) throws IOException {
try(ByteArrayOutputStream result = new ByteArrayOutputStream()) {
byte[] buffer = new byte[1024];
int length;
while ((length = inputStream.read(buffer)) != -1) {
result.write(buffer, 0, length);
}
return result.toString(UTF_8);
}
}
private InputStream urlToInputStream(URL url, Map<String, String> args) {
HttpURLConnection con = null;
InputStream inputStream = null;
try {
con = (HttpURLConnection) url.openConnection();
con.setConnectTimeout(15000);
con.setReadTimeout(15000);
if (args != null) {
for (Entry<String, String> e : args.entrySet()) {
con.setRequestProperty(e.getKey(), e.getValue());
}
}
con.connect();
int responseCode = con.getResponseCode();
/* By default the connection will follow redirects. The following
* block is only entered if the implementation of HttpURLConnection
* does not perform the redirect. The exact behavior depends to
* the actual implementation (e.g. sun.net).
* !!! Attention: This block allows the connection to
* switch protocols (e.g. HTTP to HTTPS), which is <b>not</b>
* default behavior. See: https://stackoverflow.com/questions/1884230
* for more info!!!
*/
if (responseCode < 400 && responseCode > 299) {
String redirectUrl = con.getHeaderField("Location");
try {
URL newUrl = new URL(redirectUrl);
return urlToInputStream(newUrl, args);
} catch (MalformedURLException e) {
URL newUrl = new URL(url.getProtocol() + "://" + url.getHost() + redirectUrl);
return urlToInputStream(newUrl, args);
}
}
/*!!!!!*/
inputStream = con.getInputStream();
return inputStream;
} catch (Exception e) {
throw new RuntimeException(e);
}
}
Pros
It is pure java
It can be easily enhanced by adding different headers as a map (instead of passing a null object, like the example above does), authentication, etc.
Handling of protocol switches is supported