Develop Reference

Extracting live exchange rate from an URL in java

I am trying to make a program which would exchange a given currency into a different one using live exchange rate.
This is how I get data from exchangeratesapi.io:
URL url = new URL("https://api.exchangeratesapi.io/latest?symbols=USD,GBP");
HttpURLConnection con = (HttpURLConnection) url.openConnection();
con.setRequestMethod("GET");
BufferedReader in = new BufferedReader(new InputStreamReader(
con.getInputStream()));
String inputLine;
while ((inputLine = in.readLine()) != null) {
System.out.println(inputLine);
}
The code returns what is the current exchange rate ({"rates":{"USD":1.1029,"GBP":0.84183},"base":"EUR","date":"2020-01-30"}), but I dont how to get that 1.1029 into an equation.

The "base" is the Euro. If you look on their github page here you will see in the README it says "Rates are quoted against the Euro by default. Quote against a different currency by setting the base parameter in your request." So what that means is if you put in 100, it's looking at the rate of 100 Euro. So to find another value it would be:
Amount * Exchange Rate = value for that Symbol
So in that example of 100 euro:
100 * 1.1029 = $110.29 USD.
EDIT: An update based on your comment. Here is how you would get the value, using the org.json library that you can find here.
public static void main(String[] args) throws ParseException {
String jsonString = "{ \"rates\" : { \"USD\" : 1.1029, \"GBP\" : 0.84183 }, \"base\" : \"EUR\", \"date\" : \"2020-01-30\" }";
double rate = getExchangeRate(jsonString);
System.out.println(rate);
}
public static double getExchangeRate(String jsonInput) {
JSONObject object = new JSONObject(jsonInput);
double rate = object.getJSONObject("rates").getDouble("USD");
return rate;
}
Output:
1.1029
If you're new to using this sort of stuff and JSON confuses you, I suggest you read up on some tutorials on how it works. A good start would be here.
I hope this helps!

Use the JSONObject-import:
import org.json.JSONObject;
Small change to your code in the last few lines:
URL url = new URL("https://api.exchangeratesapi.io/latest?symbols=USD,GBP");
HttpURLConnection con = (HttpURLConnection) url.openConnection();
con.setRequestMethod("GET");
BufferedReader in = new BufferedReader(new InputStreamReader(
con.getInputStream()));
String jsonText = readAll(in);
JSONObject yourData = new JSONObject(jsonText);
This is readAll:
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();
}
After that your data is a JSONObject and you can get the requested value like this:
double yourRate = yourData.getJSONObject("rates").getDouble("USD");

class Rate {
public double USD;
public double GBP;
}
class RateContainer{
public Rate rates;
public String base;
public String date;
}
in your gradle file:
dependencies {
implementation 'com.google.code.gson:gson:2.8.6'
}
Gson gson = Gson();
RateContainer container = gson.fromJson(inputLine,RateContainer.class);
Systen.out.println(container.rates.USD + "");

Googles Custom Search as if manually searched

I want to use Googles Custom Search Api for searching for song lyrics in the web via Java.
For getting the name and artist of current song playing I use Tesseract OCR. Even if the OCR works perfectly, I often don't get any results.
But when I try it manually: open Google in the web browser and search for the same string, then it works fine.
So now I don't really know what is the difference between the manual search engine and the api call.
Do I have to add some parameters to the Api request?
//The String searchString is what I am searching for, so the song name and artist
String searchUrl = "https://www.googleapis.com/customsearch/v1?key=(myKEY)=de&cx=(myID)&q=" + searchString + "lyrics";
String data = getData(searchUrl);
JSONObject json = new JSONObject(data);
String link = "";
try
{
link = json.getJSONArray("items").getJSONObject(0).getString("link");
URI url = new URI(link);
System.out.println(link);
Desktop.getDesktop().browse(url);
}
catch(Exception e)
{
System.out.println("No Results");
}
private static String getData(String _urlLink) throws IOException
{
StringBuilder result = new StringBuilder();
URL url = new URL(_urlLink);
URLConnection conn = url.openConnection();
BufferedReader rd = new BufferedReader(new InputStreamReader(conn.getInputStream()));
String line;
while((line = rd.readLine()) != null)
{
result.append(line);
}
rd.close();
return result.toString();
}

Try to remove =de before &cx and use + to represent the space between words. Like this - https://www.googleapis.com/customsearch/v1?key=(yourKEY)&cx=(yourID)&q=paradise+coldplay+lyrics

I am using the epublib and I am trying to get the entire chapter of a book at a time

I am trying to get one chapter at a time of a book. I am using the Paul Seigmann library. However, I am not sure how to do it but I am able to get all the text from the book. Not sure where to go from there.
// find InputStream for book
InputStream epubInputStream = assetManager
.open("the_planet_mappers.epub");
// Load Book from inputStream
mThePlanetMappersBookEpubLib = (new EpubReader()).readEpub(epubInputStream);
Spine spine = new Spine(mThePlanetMappersBookEpubLib.getTableOfContents());
for (SpineReference bookSection : spine.getSpineReferences()) {
Resource res = bookSection.getResource();
try {
InputStream is = res.getInputStream();
BufferedReader r = new BufferedReader(new InputStreamReader(is));
String line;
while ((line = r.readLine()) != null) {
line = Html.fromHtml(line).toString();
Log.i("Read it ", line);
mEntireBook.append(line);
}
} catch (IOException e) {
}

I don't know if you're still looking for an answer, but...
I'm working on it too right now. This is the code I have to retrieve the content of all the epub file:
public ArrayList<String> getBookContent(Book bi) {
// GET THE CONTENTS OF ALL PAGES
StringBuilder string = new StringBuilder();
ArrayList<String> listOfPages = new ArrayList<>();
Resource res;
InputStream is;
BufferedReader reader;
String line;
Spine spine = bi.getSpine();
for (int i = 0; spine.size() > i; i++) {
res = spine.getResource(i);
try {
is = res.getInputStream();
reader = new BufferedReader(new InputStreamReader(is));
while ((line = reader.readLine()) != null) {
// FIRST PAGE LINE -> <?xml version="1.0" encoding="utf-8" standalone="no"?>
if (line.contains("<?xml version=\"1.0\" encoding=\"utf-8\" standalone=\"no\"?>")) {
string.delete(0, string.length());
}
// ADD THAT LINE TO THE FINAL STRING REMOVING ALL THE HTML
string.append(Html.fromHtml(formatLine(line)));
// LAST PAGE LINE -> </html>
if (line.contains("</html>")) {
listOfPages.add(string.toString());
}
}
} catch (IOException e) {
e.printStackTrace();
}
}
return listOfPages;
}
private String formatLine(String line) {
if (line.contains("http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd")) {
line = line.substring(line.indexOf(">") + 1, line.length());
}
// REMOVE STYLES AND COMMENTS IN HTML
if ((line.contains("{") && line.contains("}"))
|| ((line.contains("/*")) && line.contains("*/"))
|| (line.contains("<!--") && line.contains("-->"))) {
line = line.substring(line.length());
}
return line;
}
As you may have notice I need to improve the filter, but I have every chapter of that book in my ArrayList. Now I just need to call that ArrayList like myList.get(0); and is done.
To show the text in a proper way, I'm using the bluejamesbond:textjustify library (https://github.com/bluejamesbond/TextJustify-Android).
It is easy to use and powerful.
I hope it helps you, and if anybody finds a better way to filter that html, notice me, please.

How to Properly Check for JSON Updates - Java

I'm trying to make a program to check for announcements via a web API - This connects to a remote server and reads the JSON on the page - I cannot test my code as the server is not live yet. Would this work & be the correct way to go about this?
public class AnnouncementChecker implements Runnable{
private final String announcementsURL = "REDACTED";
private String lastAnnouncement = "";
#Override
public void run(){
try {
URL url = new URL(announcementsURL);
HttpURLConnection http = (HttpURLConnection) url.openConnection();
http.setRequestMethod("conditional GET");
http.setRequestProperty("Connection", "keep-alive");
http.setUseCaches(true);
http.setAllowUserInteraction(false);
if (lastAnnouncement != ""){
http.setRequestProperty("If-Modified-Since", lastAnnouncement);
}
http.setConnectTimeout(10);
http.connect();
int status = http.getResponseCode();
if (status == 304 || (status == 200 && lastAnnouncement == "")){
lastAnnouncement = http.getHeaderField("Last-Modified");
BufferedReader br = new BufferedReader(new InputStreamReader(http.getInputStream()));
StringBuilder sb = new StringBuilder();
String line;
while ((line = br.readLine()) != null) {
sb.append(line+"\n");
}
br.close();
String json = sb.toString();
JSONParser parser = new JSONParser();
JSONObject jsonResponse = (JSONObject) parser.parse(json);
//String announcement = (String) jsonResponse.get("message");
//TODO What to do with announcement...
}
http.getInputStream().close();
http.disconnect();
} catch (IOException | ParseException e) {
e.printStackTrace();
}
}
}

I would recommend setting up a test of some kind, despite the server not being available. This would give you the answer to your question and the test would be there forever going forward to protect you when you make changes to the code and the business requirements change.
To help you with that I would recommend splitting up the code that returns the response and the code that does the parsing. That way you can test the parsing independent of the part that makes the HTTP connection.
If you have no idea how to do that then I'd be happy to post an example for you.

Regular expressions in Java, can't search all HTML

I'm working with Java regular expressions on Android platform.
I'm trying to search this HTML for defined a regular expression.
Here's my code:
public void mainaaForWWW(String websiteSource){
try {
websiteSource = readDataFromWWW(websiteSource);
} catch (IOException e1) {
e1.printStackTrace();
}
ArrayList<String> cinemaArray = new ArrayList<String>();
Pattern sample = Pattern.compile("<div class=\"theatre\">");
Matcher secuence = sample.matcher(websiteSource);
try {
while (secuence.find()) {
cinemaArray.add(secuence.group());
}
} catch (Exception e) {
e.printStackTrace();
}
titleTableForWWW = new String[cinemaArray.size()];
for(int i = 0; i < titleTableForWWW.length; i++)
titleTableForWWW[i] = cinemaArray.get(i);
}
The problem is quite strange, because when I debug the code, String websiteSource is okay (all HTML files are completely loaded), but there's only 4 while loops. In the HTML document I found manually 11 matches. This regex is simplified only to find what's going on. Any ideas?
Ok, my bad. I found a solution:
So, here's my code responsible for writing HTML source code to String:
public String readDataFromWWW(String UrlAdress) throws IOException
{
String line = null;
URL url = new URL(UrlAdress);
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
BufferedReader rd = new BufferedReader(new InputStreamReader(conn.getInputStream(), "ISO-8859-2"));
while (rd.readLine() != null) {
line += rd.readLine();
}
System.out.println(line);
return line;
I think that reading to string that way, may something messed up, so I replaced this method by this one:
public String readDataFromWWW(String UrlAdress) throws IOException
{
String wyraz = "";
try {
String webPage = UrlAdress;
URL url = new URL(webPage);
URLConnection urlConnection = url.openConnection();
InputStream is = urlConnection.getInputStream();
InputStreamReader isr = new InputStreamReader(is, "ISO-8859-2");
int numCharsRead;
char[] charArray = new char[1024];
StringBuffer sb = new StringBuffer();
while ((numCharsRead = isr.read(charArray)) > 0) {
sb.append(charArray, 0, numCharsRead);
}
wyraz = sb.toString();
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return wyraz;
}
And everything works FINE! Thanks a lot for clues and help. I think the problem was connected with newline durring writing String, but I'm not quite sure.