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javaapicurrencyconverters

Currency Converter App in GUI JAVA using live exchange rates


I am trying to get live exchange rates for my java exchange currency program. I saw that this could be done using API from the internet and import the website URL in the java program to get live exchange rates. However I am having trouble working with JSON and getting a few more errors that prevent me from running the program. I am not sure what to import in order to fix the errors. I am quite new and I am not sure if this should be difficult or am I doing something wrong here. Thank you in advance.

`

package currencyConverterGUI;

import javax.swing.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.text.DecimalFormat; // import for decimal place limitation
import java.net.URL;
import org.json.JSONObject;
import java.io.*;
import java.net.URLConnection;

public class currencyGUI extends JFrame //inherit from JFrame
{



    private static final DecimalFormat df = new DecimalFormat("0.00000");  // use DecimalFormat to round double numbers to 5 decimal places


    private JButton btnConvert; // generated by GUI designer
    private JPanel JPanelMain; // generated by GUI designer
    private JTextField textAmount; // generated by GUI designer
    private JComboBox textFrom; // generated by GUI designer
    private JComboBox textTo; // generated by GUI designer
    private JLabel result; // generated by GUI designer


    public currencyGUI() {


        btnConvert.addActionListener(new ActionListener() { // button reacts to user click; generated by GUI designer

            @Override
            public void actionPerformed(ActionEvent e)
            {


                double total;
                double amount = Double.parseDouble(textAmount.getText()); // check if input amount is a number and read the input if it is a number
                int index = textTo.getSelectedIndex(); //get index of selected currency from the first combo box

                if(textFrom.getSelectedItem() == "USD")  // if USD is selected in the first combo box, then switch for each currency
                {

                    switch (index) {

                        case 0:
                            total = amount * 1;
                            result.setText(df.format(total) + " USD");
                            break;

                        case 1:
                            total = amount * 0.86;
                            result.setText(df.format(total) + " EUR");
                            break;

                        case 2:
                            total = amount * 1.88;
                            result.setText(df.format(total) + " BGN");
                            break;

                        case 3:
                            total = amount * 0.000060;
                            result.setText(df.format(total) + " BTC");
                            break;

                        case 4:
                            total = amount * 2.98;
                            result.setText(df.format(total) + " ADA");
                            break;

                    }
                }

                    if(textFrom.getSelectedItem() == "EUR")  // if EUR is selected in the first combo box, then switch for each currency
                    {

                        switch (index) {

                            case 0:
                                total = amount * 1.04;
                                result.setText(df.format(total) + " USD");
                                break;

                            case 1:
                                total = amount * 0.1;
                                result.setText(df.format(total) + " EUR");
                                break;

                            case 2:
                                total = amount * 1.95;
                                result.setText(df.format(total) + " BGN");
                                break;

                            case 3:
                                total = amount * 0.000063;
                                result.setText(df.format(total) + " BTC");
                                break;

                            case 4:
                                total = amount * 3.18;
                                result.setText(df.format(total) + " ADA");
                                break;

                        }
                    }

                        if(textFrom.getSelectedItem() == "BGN")  // if BGN is selected in the first combo box, then switch for each currency
                        {

                            switch (index) {

                                case 0:
                                    total = amount * 0.53;
                                    result.setText(df.format(total) + " USD");
                                    break;

                                case 1:
                                    total = amount * 0.51;
                                    result.setText(df.format(total) + " EUR");
                                    break;

                                case 2:
                                    total = amount * 1;
                                    result.setText(df.format(total) + " BGN");
                                    break;

                                case 3:
                                    total = amount * 0.000032;
                                    result.setText(df.format(total) + " BTC");
                                    break;

                                case 4:
                                    total = amount * 1.63;
                                    result.setText(df.format(total) + " ADA");
                                    break;

                            }
                        }

                            if(textFrom.getSelectedItem() == "BTC")  // if BTC is selected in the first combo box, then switch for each currency
                            {

                                switch (index) {

                                    case 0:
                                        total = amount * 16446.8;
                                        result.setText(df.format(total) + " USD");
                                        break;

                                    case 1:
                                        total = amount * 15851.4;
                                        result.setText(df.format(total) + " EUR");
                                        break;

                                    case 2:
                                        total = amount * 31043.1;
                                        result.setText(df.format(total) + " BGN");
                                        break;

                                    case 3:
                                        total = amount * 1;
                                        result.setText(df.format(total) + " BTC");
                                        break;

                                    case 4:
                                        total = amount * 50467.4;
                                        result.setText(df.format(total) + " ADA");
                                        break;

                                }
                            }

                                if(textFrom.getSelectedItem() == "ADA")  // if ADA is selected in the first combo box, then switch for each currency
                                {

                                    switch (index) {

                                        case 0:
                                            total = amount * 0.33;
                                            result.setText(df.format(total) + " USD");
                                            break;

                                        case 1:
                                            total = amount * 0.32;
                                            result.setText(df.format(total) + " EUR");
                                            break;

                                        case 2:
                                            total = amount * 0.62;
                                            result.setText(df.format(total) + " BGN");
                                            break;

                                        case 3:
                                            total = amount * 0.000020;
                                            result.setText(df.format(total) + " BTC");
                                            break;

                                        case 4:
                                            total = amount * 1;
                                            result.setText(df.format(total) + " ADA");
                                            break;

                                    }
                                }
                }


        });
    }


    public static void main(String[] args) throws Exception {
        JFrame frame = new JFrame("Currency Converter");
        frame.setContentPane(new currencyGUI().JPanelMain);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.pack();
        frame.setVisible(true); // make pane visible



        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);
            }
    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();

    }



        }





`

I have tried importing

import org.json.JSONObject;

and

import java.net.URLConnection;

but this doesn't fix the error.

Solution

  • So there is a lot going on in your code. I recommend you to refactor your program, it has a lot of repetitions.

    Regarding the required libraries:
    importing JSONObject probably does not work because you haven't listed it in your dependencies.
    For maven check out: https://mvnrepository.com/artifact/org.json/json
    If you're not using a dependency management tool download the jar from here: https://mvnrepository.com/artifact/org.json/json


    There is also no use for `import java.net.URLConnection;`
    I used `import java.net.HttpURLConnection; import java.net.URL;` and it worked.