Question

• Please write this in Java, please write comments as you create it, and please follow the coding instructions.
• As you are working on this project, add print statements or use the debugger to help you verify what is happening. Write and test the project one line at a time.
• Before you try to obtain currency exchange rates, obtain your free 32 character access code from this website:

  https://fixer.io/
   Here's the code:  46f27e9668fcdde486f016eee24c554c

• Choose five international source currencies to monitor. Each currency is referenced with a three letter ISO 4217 currency code. For example, the code for the British Pounds is GBP. " Place these currency codes in a text file named currency.txt.
• Use these codes: Colombian Peso: COP: 3540 .250862, Costa Rican Colon CRC: 685.938731, Egyptian Pound EGP: 19.758935, Jamaican Dollar JMD: 150.549578, and Yen JPY: 124.536082 place them in a file called currency.text​​​​​
• Use try..catch blocks to handle all exceptions with a user-friendly messages in the catch blocks. Do not throw any exceptions.
• In a while loop that terminates when the end of file is reached, do the following:
  1. Read the next currency from the currencies.txt file.
  2. Create a URL for the fixer.io site that will obtain a URL for obtaining the exchange rate using the currency read in Step 1 as the target currency (symbol) and EUR as the source currency (base). Which you code:

     http://data.fixer.io/api/latest​​​​​​

     ? access_key = 46f27e9668fcdde486f016eee24c554c or YOUR_ACCESS_KEY instead of the code itself, one of them should work

       & symbols = COP,CRC,EGP,JMD,JPY

  3. Using the URL from Step 2, create a scanner object that reads the JSON string from the website. Extract the exchange rate from the JSON string.
  4. Add a bar to a JFreeChart bar chart, whose height is the exchange rate from Step 3. This is the bar chart example:

     // JAR files jcommon-1.0.23.jar and jfreechart-1.0.19.jar 
     // must be added to project.
     
     import java.io.*;
     import org.jfree.data.category.DefaultCategoryDataset;
     import org.jfree.chart.ChartFactory; 
     import org.jfree.chart.plot.PlotOrientation;
     import org.jfree.chart.JFreeChart; 
     import org.jfree.chart.ChartUtilities; 
     public class BarChart {  
         public static void main(String[] args) {
             try {
                    
                 // Define data for line chart.
                 DefaultCategoryDataset barChartDataset = 
                     new DefaultCategoryDataset();
                 barChartDataset.addValue(1435, "total", "East");
                 barChartDataset.addValue(978,  "total", "North");
                 barChartDataset.addValue(775,  "total", "South");                
                 barChartDataset.addValue(1659, "total", "West");                
                     
                 // Define JFreeChart object that creates line chart.
                 JFreeChart barChartObject = ChartFactory.createBarChart(
                     "Sales ($1000)", "Region", "Sales", barChartDataset,
                     PlotOrientation.VERTICAL, 
                     false,  // Include legend.
                     false,  // Include tooltips.
                     false); // Include URLs.               
                               
                  // Write line chart to a file.               
                  int imageWidth = 640;
                  int imageHeight = 480;                
                  File barChart = new File("sales.png");              
                  ChartUtilities.saveChartAsPNG(
                      barChart, barChartObject, imageWidth, imageHeight); 
             }
           
             catch (Exception i)
             {
                 System.out.println(i);
             }
         }
     }

  
  Identify the source code items that belong before, in, and after the while loop.
• Don't forget to close each scanner when you are finished using it.
• Your project should contain only a single class, which contains the main method. This class must define at least three additional static methods that modularize the tasks in this project. For example, you might define methods such as these:

  public static String getCurrency(Scanner s)
  public static String getUrlString(String targetCurrency)
  public static double getExchangeRate(String urlString)
  

  If you wish, use the Eclipse Refactor capability to extract the methods.
• Here is suggested pseudocode for the whole project. You can get this to work first and then extract the methods, either by hand or using Eclipse Refactor:

  create File object for currencies.txt
  create scanner1 to read from input file
  create new DefaultCategoryDataset object to 
      contain bars for histogram
  while more lines in input file
      read target currency using scanner1
      construct URL for obtaining target exchange rate
      create scanner2 from URL
      use URL to obtain JSON string
      extract target exchange rate from JSON string
      add histogram bar representing target 
          exchange rate to DefaultCategoryDataset object
      close scanner2
  end while
  create a bar chart object from DefaultCategoryDataset
      object
  create graphics image file
  close scanner1

Answer 1

package HomeworkLib;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.Scanner;
import org.jfree.chart.ChartFactory;
import org.jfree.chart.ChartUtilities;
import org.jfree.chart.JFreeChart;
import org.jfree.chart.plot.PlotOrientation;
import org.jfree.data.category.DefaultCategoryDataset;

public class Barcha {

   public static void main(String[] args) throws MalformedURLException, IOException{
           

       Scanner s = new Scanner(new File("currencies.txt"));
       double[] b = new double[5];
       // loop to determine currency values based on currencies.txt
        for(int i=0; s.hasNextLine( );i++) {
            String sourceCurrency = getCurrency(s);
            String url = getURLString(sourceCurrency);
            double exchangeRate = getExchangeRate(url);
            System.out.println(exchangeRate);
            //assigns each exchangerate value into an array
            b[i]= exchangeRate;
        }
        s.close( );
   // Define data for barchart.
        DefaultCategoryDataset barChartDataset = new DefaultCategoryDataset();
      
        //bar for Swiss Franc
        barChartDataset.addValue(b[0], "total", "CHF");
        //bar for Nigerian Naira
        barChartDataset.addValue(b[1], "total", "NGN");
      
        //United Arab Emirates dirham
        barChartDataset.addValue(b[2], "total", "AED");
        //Lebanise pounds
        barChartDataset.addValue(b[3], "total", "LBP");
        //British pounds
        barChartDataset.addValue(b[4], "total", "GBP");  
        // Define JFreeChart object that creates line chart.
        JFreeChart barChartObject = ChartFactory.createBarChart(
            "Value", "Name of Currencies", "USD", barChartDataset,
            PlotOrientation.VERTICAL,
            false, // Include legend.
            false, // Include tooltips.
            false); // Include URLs.             
                    
         // Write line chart to a file.             
         int imageWidth = 640;
         int imageHeight = 480;              
         File barChart = new File("sales.png");            
         ChartUtilities.saveChartAsPNG(
             barChart, barChartObject, imageWidth, imageHeight);
      
   }

   private static double getExchangeRate(String url) throws IOException, MalformedURLException {
       //Scanner to find URL input and open it
       Scanner fromWeb = new Scanner((new URL(url)).openStream( ));
       String line = fromWeb.nextLine( );
       fromWeb.close( );
       //splits exchangeRate
       double exchangeRate = Double.parseDouble(line.split(",")[1]);
       return exchangeRate;
   }

   private static String getCurrency(Scanner s) {
       //reads from scanner in main method to determine if there's a nextline available
       String sourceCurrency = s.nextLine( );
       return sourceCurrency;
   }

   private static String getURLString(String sourceCurrency) {
       //Uses Suffix and prefix to find and calculate currency value
       //compared with the target currency
       String prefix = "http://download.finance.yahoo.com/d/quotes.csv?s=";
       String suffix = "=X&f=sl1d1t1ba&e=.csv";
       String targetCurrency = "USD";
       String url = prefix + sourceCurrency + targetCurrency + suffix;
       return url;
   }  

}