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 + "");
Related
I am trying to use this api to get report with java, and here is the link
https://developers.google.com/admin-sdk/reports/v1/appendix/activity/meet
and here is what i am using now
public static String getGraph() {
String PROTECTED_RESOURCE_URL = "https://www.googleapis.com/admin/reports/v1/activity/users/all/applications/meet?eventName=call_ended&maxResults=10&access_token=";
String graph = "";
try {
URL urUserInfo = new URL(PROTECTED_RESOURCE_URL + "access_token");
HttpURLConnection connObtainUserInfo = (HttpURLConnection) urUserInfo.openConnection();
if (connObtainUserInfo.getResponseCode() == HttpURLConnection.HTTP_OK) {
StringBuilder sbLines = new StringBuilder("");
BufferedReader reader = new BufferedReader(
new InputStreamReader(connObtainUserInfo.getInputStream(), "utf-8"));
String strLine = "";
while ((strLine = reader.readLine()) != null) {
sbLines.append(strLine);
}
graph = sbLines.toString();
}
} catch (IOException ex) {
x.printStackTrace();
}
return graph;
}
I am pretty sure it's not a smart way to do that and the string I get is quite complex, are there any jave sample that i can get the data directly instead of using java origin httpRequest
Or, are there and class I can import to switch the json string to the object!?
Anyone can help?!
I have trying this for many days already!
Thanks!!
I created a post request with json and it works pretty well. But now I want to insert the output of this json post request into my database.
So I need to create a json parser to seperate the string like this: "Bestellnummer:1", "Besteller:8195529", "Zeit: 2019-09-27 15:50:07", "Artikelnummer:76194", "Anzahl:1", "Preis:2.968"... (next Artikelnummer and so on...).
Bestellnummer = orderid, Besteller = customerid, Zeit = time, Artikelnummer=articleid, Anzahl = number of article, Preis= price
I tried to do something like a parser in my code, but I never did something like this befor and unfortuntly don't know how to involve this parser in my code.
I hope u can help me
One example for my json Output:
{"Bestellnummer":"1","Besteller":"8195529","Zeit":"2019-09-27 15:50:07","Artikel":[{"Artikelnummer":"76194","Anzahl":"1","Preis":"2.968"},{"Artikelnummer":"61681","Anzahl":"1","Preis":"7.147"},{"Artikelnummer":"111756","Anzahl":"1","Preis":"9.29"},{"Artikelnummer":"14227","Anzahl":"1","Preis":"0"}]}
Code:
private static String dirPath = "https://hauteuchdrum.informatik.uni-siegen.de/propra/aufgaben/ws1920/index.php";
public ArrayList<String> Bestellung(){
File file = new File (dirPath + "//array_complex.json");
ArrayList <String> test = new ArrayList<String>();
try {
String str = "{ \"Bestellnummer\": [1,2,3,4,5] }";
// holt alle 47550 bestellungen vom json
for (int i=1; i<2;i++) {
String POST_PARAMS = "json={\"bid\":\"bid\", \"getorder\":\""+i+"\"}";
//System.out.println(POST_PARAMS);
JSONObject obj1 = new JSONObject(POST_PARAMS);
JSONArray arr=obj1.getJSONArray("Bestellnummer");
for (int z=0; z<arr.length();z++) {
String post_id = arr.getJSONObject(z).getString("Bestellnummer");
System.out.println(post_id);
}
URL obj = new URL("https://hauteuchdrum.informatik.uni-siegen.de/propra/aufgaben/ws1920/index.php");
HttpURLConnection postConnection = (HttpURLConnection) obj.openConnection();
postConnection.setRequestMethod("POST");
postConnection.setRequestProperty("connection", "Keep-Alive");
postConnection.setDoOutput(true);
java.io.OutputStream os = postConnection.getOutputStream();
os.write(POST_PARAMS.getBytes());
os.flush();
os.close();
int responseCode = postConnection.getResponseCode();
//System.out.println("POST Response Code : " + responseCode);
// System.out.println("POST Response Message : " + postConnection.getResponseMessage());
if (responseCode == HttpURLConnection.HTTP_OK) { //success
BufferedReader in = new BufferedReader(new InputStreamReader(postConnection.getInputStream()));
String inputLine;
StringBuffer response = new StringBuffer();
while ((inputLine = in.readLine()) != null) {
response.append(inputLine);
}
in.close();
// print result
// System.out.println(response.toString());
test.add(response.toString());
// java.util.Iterator<String> it = test.iterator();
// while (it.hasNext()) {
// System.out.println(it.next());
// }
}
}
}
catch (Exception e) {
System.out.println();
}
return test;
}
If what you want to do is to insert the HTTP response string into database, I strongly recommend you to deserialize the string to POJOs as follows:
Declare 2 classes - MyResponse and Artikel. Artikel is for storing the content of JOSN object in JSON array, and I use List<Artikel> for the JSON array. BTW, I also use #JsonProperty(provided in Jackson) to map JSON keys with uppercase to variables with lowercase.
class MyResponse {
#JsonProperty(value="Bestellnummer")
private String bestellnummer;
#JsonProperty(value="Besteller")
private String besteller;
#JsonProperty(value="Zeit")
private String zeit;
#JsonProperty(value="Artikel")
private List<Artikel> artikel;
//general getters and setters
}
class Artikel {
#JsonProperty(value="Artikelnummer")
private String artikelnummer;
#JsonProperty(value="Anzahl")
private String anzahl;
#JsonProperty(value="Preis")
private String preis;
//general getters and setters
}
Now, you can use Jackson (one of the most popular JSON libraries) to deserialize the HTTP response to our POJOs. And you can manipulate these POJOs for DB operation easily.
ObjectMapper mapper = new ObjectMapper();
MyResponse myResponse = mapper.readValue(response.toString(), MyResponse.class);
myResponse.getArtikel().forEach(System.out::println);
Console output
Artikel [artikelnummer=76194, anzahl=1, preis=2.968]
Artikel [artikelnummer=61681, anzahl=1, preis=7.147]
Artikel [artikelnummer=111756, anzahl=1, preis=9.29]
Artikel [artikelnummer=14227, anzahl=1, preis=0]
Because you provided too less information to come up with a more detailed answer I came up with the following code.
JSONObject main = new JSONObject(data);
String orderNumber = main.getString("Bestellnummer"); // Retrieving the order number
String orderUserId = main.getString("Besteller"); // Retrieving the orderUserId
String time = main.getString("Zeit"); // Retrieving the current time
JSONArray articles = main.getJSONArray("Artikel"); // Getting articles as JSON Array
for (int i = 0; i < articles.length(); i++) { // Looping tough the articles
JSONObject article = articles.getJSONObject(i); // Getting the article JSON Object
String articleNumber = article.getString("Artikelnummer"); // Retrieving the Article number
String amount = article.getString("Anzahl"); // Retrieving the amount
String price = article.getString("Pris"); // Retrieving the price
// Your code...
}
I hope this helps you.
I am going to get the JSON from the localhost db. Then, I want to put the json into ArrayList. I want to call the parseJSON function. But the JSON is null. Where I should call the function, thanks so much:))
#Override
protected String doInBackground(Void... voids) {
try {
URL url = new URL(urlWebService);
HttpURLConnection con = (HttpURLConnection) url.openConnection();
con.setRequestMethod("GET");
StringBuilder sb = new StringBuilder();
InputStream input = con.getInputStream();
BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(input));
String json;
while ((json = bufferedReader.readLine()) != null) {
sb.append(json + "\n");
}
parseJSON(json);
return sb.toString().trim();
} catch (Exception e) {
return null;
}
}
}
GetJSON getJSON = new GetJSON(
);
getJSON.execute();
}
private void parseJSON(String json) {
Gson gson = new Gson();
Type type = new TypeToken<List<EssayElement>>(){}.getType();
List<EssayElement> mList = gson.fromJson(json, type);
for (EssayElement essayElement : mList){
Log.i("Message: " +
"", essayElement.id + "-" + essayElement.title + "-" + essayElement.essay + "-" + essayElement.date + "-" + essayElement.time);
}
}
null object reference with String"json"
I would suggest using a proper http library that handles making requests for you like Volley or Retrofit... JSON and Error handling are also builtin, so AsyncTask can completely be removed for that purpose
But what you have is fine, only json shouldn't be used after the while loop, it's only the last line of the http response, not the full json (assuming there's multiple lines)
You should really consider parsing the results in the onPostExecute, and possibly even having the parse method return an actual object, or display to the UI
You are appending the string to StringBuilder sb = new StringBuilder();. You have to call like this parseJSON(sb.toString()); cause String json is just a pointer doesn't hold the actual string, you want.
BufferedReader reader = new BufferedReader(new InputStreamReader(conn.getInputStream()));
StringBuilder sb = new StringBuilder();
String line = null;
while ((line = reader.readLine()) != null) {
sb.append(line + "\n");
}
String json = sb.toString();
You can instead use my code snippet it's working fine for me. now you can use son variable for your private void parseJSON(String json) function.
I would like to pass some values i have from a string in to double variables. the string output looks like this:
{
"high":"1635.07",
"last":"1635.07",
"timestamp":"1489299397",
"volume":"321.34139374",
"vwap":"1602.72987907",
"low":"1595.03",
"ask":"1635.89",
"bid":"1605.10"
}
I just want this data to be like:
double high = (value of high in string);
double last = (value of last in string);
ect...
Im having trouble as java throws an error I believe because of the mix of words and numbers.
Thanks in advance for the help.
code:
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
import javax.swing.JOptionPane;
public class btc {
private final String USER_AGENT = "Mozilla/5.0";
public static void main(String[] args) throws Exception {
btc http = new btc();
http.sendGet();
}
// HTTP GET request
private void sendGet() throws Exception {
String url = "https://api.quadrigacx.com/v2/ticker?book=btc_cad";
URL obj = new URL(url);
HttpURLConnection con = (HttpURLConnection) obj.openConnection();
// optional default is GET
con.setRequestMethod("GET");
//add request header
con.setRequestProperty("User-Agent", USER_AGENT);
System.out.println("\nSending 'GET' request to URL : " + url);
BufferedReader in = new BufferedReader(
new InputStreamReader(con.getInputStream()));
String inputLine;
StringBuffer response = new StringBuffer();
while ((inputLine = in.readLine()) != null) {
response.append(inputLine);
}
//write to variables
String test = response.toString();
//double high = test("high");
//Double high = Double.parseDouble(test);
System.out.println(test);
//print result
//JOptionPane.showMessageDialog(null, response.toString());
}
}
As already mentioned in the comments what you receiving from the server is a JSON object as documented in QuadrigaCX's API description so it should be parsed as such as the order of the members may vary aswell as the whitespace.
What's interesting about this JSON string is that all values are actually strings as they are enclosed in double quotation marks. But these strings contain values that can be interpreted and parsed as double.
Using minimal-json, which is a minimalistic Java library that allows you to parse JSON and access contained values directly. The following code makes use of it and "reads" high and last as double values:
JsonObject jsonObject = Json.parse(responseBody).asObject();
double high = Double.parseDouble(jsonObject.get("high").asString());
double last = Double.parseDouble(jsonObject.get("last").asString());
Here responseBody corresponds to what you have named test in your sendGet method and is the response from the web server as one string.
How do I create a Java program that enters the words "Hello World" into Google and then retrieves the html from the results page? I'm not trying to use the Robot class.
URL url = new URL("http://www.google.com/search?q=hello+world");
url.openStream(); // returns an InputStream which you can read with e.g. a BufferedReader
If you make repeated programmatic requests to Google in this way they will start to redirect you to "we're sorry but you look like a robot" pages pretty quick.
What you may be better doing is using Google's custom search api.
For performing google search through a program, you will need a developer api key and a custom search engine id. You can get the developer api key and custom search engine id from below urls.
https://cloud.google.com/console/project'>Google Developers Console
https://www.google.com/cse/all'>Google Custom Search
After you got the both the key and id use it in below program. Change apiKey and customSearchEngineKey with your keys.
For step by step information please visit - http://www.basicsbehind.com/google-search-programmatically/
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
public class CustomGoogleSearch {
final static String apiKey = "AIzaSyAFmFdHiFK783aSsdbq3lWQDL7uOSbnD-QnCnGbY";
final static String customSearchEngineKey = "00070362344324199532843:wkrTYvnft8ma";
final static String searchURL = "https://www.googleapis.com/customsearch/v1?";
public static String search(String pUrl) {
try {
URL url = new URL(pUrl);
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
BufferedReader br = new BufferedReader(new InputStreamReader(connection.getInputStream()));
String line;
StringBuffer buffer = new StringBuffer();
while ((line = br.readLine()) != null) {
buffer.append(line);
}
return buffer.toString();
} catch (Exception e) {
e.printStackTrace();
}
return null;
}
private static String buildSearchString(String searchString, int start, int numOfResults) {
String toSearch = searchURL + "key=" + apiKey + "&cx=" + customSearchEngineKey + "&q=";
// replace spaces in the search query with +
String newSearchString = searchString.replace(" ", "%20");
toSearch += newSearchString;
// specify response format as json
toSearch += "&alt=json";
// specify starting result number
toSearch += "&start=" + start;
// specify the number of results you need from the starting position
toSearch += "&num=" + numOfResults;
System.out.println("Seacrh URL: " + toSearch);
return toSearch;
}
public static void main(String[] args) throws Exception {
String url = buildSearchString("BasicsBehind", 1, 10);
String result = search(url);
System.out.println(result);
}
}