Przelicznik walut - wersja XML

src/main/java/waluty/wersja_xml/ObslugaNBP.java

+package waluty.wersja_xml;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.math.BigDecimal;
+import java.net.URL;
+import java.time.LocalDate;
+
+import javax.xml.parsers.DocumentBuilder;
+import javax.xml.parsers.DocumentBuilderFactory;
+import javax.xml.parsers.ParserConfigurationException;
+import javax.xml.xpath.XPath;
+import javax.xml.xpath.XPathConstants;
+import javax.xml.xpath.XPathExpressionException;
+import javax.xml.xpath.XPathFactory;
+
+import org.w3c.dom.Document;
+import org.w3c.dom.Node;
+import org.w3c.dom.NodeList;
+import org.xml.sax.SAXException;
+
+public class ObslugaNBP {
+	private static final String ADRES = "http://api.nbp.pl/api/exchangerates/tables";
+
+	/** Pobiera tabelę z bieżącymi kursami walut.
+	 * Zwraca null w przypadku błędów.
+	 */
+	public static Tabela pobierzBiezaceKursy() {
+		Document doc = wczytajXmlZAdresu(ADRES + "/A?format=xml");
+		return tabelaZXml(doc);
+	}
+	
+	/** Pobiera tabelę z archiwalnymi kursami walut z określonej daty.
+	 * Zwraca null w przypadku błędów, np. wtedy, gdy dla danej daty nie istnieje tabela.
+	 */
+	public static Tabela pobierzKursyHistoryczne(String data) {
+		Document doc = wczytajXmlZAdresu(ADRES + "/A/" + data + "?format=xml");
+		return tabelaZXml(doc);
+	}
+
+	private static Document wczytajXmlZAdresu(String adres) {
+		// Document Object Model
+		
+		try {
+			DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
+			DocumentBuilder db = dbf.newDocumentBuilder();
+
+			URL url = new URL(adres);
+			try (InputStream in = url.openStream()) {
+				return db.parse(in);
+			}
+		} catch (ParserConfigurationException | SAXException | IOException e) {
+			e.printStackTrace();
+			return null;
+		}
+	}
+
+	private static Tabela tabelaZXml(Document doc) {
+		if (doc == null)
+			return null;
+		try {
+			XPathFactory xpf = XPathFactory.newInstance();
+			XPath xpath = xpf.newXPath();
+
+			// String numer = xpath.evaluate(
+			// "/ArrayOfExchangeRatesTable/ExchangeRatesTable/No", doc);
+
+			String nazwaTabeli = xpath.evaluate("//Table", doc);
+			String numerTabeli = xpath.evaluate("//No", doc);
+			LocalDate data = LocalDate.parse(xpath.evaluate("//EffectiveDate", doc));
+
+			Tabela tabela = new Tabela(nazwaTabeli, numerTabeli, data);
+
+			NodeList rates = (NodeList) xpath.evaluate("//Rate", doc, XPathConstants.NODESET);
+			final int n = rates.getLength();
+			for (int i = 0; i < n; i++) {
+				Node rate = rates.item(i);
+				String kod = xpath.evaluate("Code", rate);
+				String nazwa = xpath.evaluate("Currency", rate);
+				String kurs = xpath.evaluate("Mid", rate);
+				BigDecimal kursBD = new BigDecimal(kurs);
+				Waluta waluta = new Waluta(kod, nazwa, kursBD);
+				tabela.dodaj(waluta);
+			}
+
+			return tabela;
+		} catch (XPathExpressionException e) {
+			e.printStackTrace();
+			return null;
+		}
+	}
+}
\ No newline at end of file

src/main/java/waluty/wersja_xml/PrzelicznikWalutKonsola.java

+package waluty.wersja_xml;
+
+import java.math.BigDecimal;
+import java.util.Scanner;
+
+public class PrzelicznikWalutKonsola {
+
+	public static void main(String[] args) {
+		System.out.println("Pobieram aktualne kursy...");
+		Tabela tabela = ObslugaNBP.pobierzBiezaceKursy();
+		System.out.println(tabela);
+		
+		Scanner sc = new Scanner(System.in);
+		
+		while(true) {
+			System.out.println("\nPodaj kod waluty");
+			String kod = sc.nextLine().trim().toUpperCase();
+			if(kod == null || kod.isEmpty())
+				break;
+			
+			Waluta waluta = tabela.znajdz(kod);
+			if(waluta == null) {
+				System.out.println("Nie ma takiej waluty.");
+				continue;
+			}
+			
+			System.out.println("Wybrana waluta: " + waluta.getNazwa());
+			System.out.println("Podaj kwotę");
+			if(!sc.hasNextBigDecimal()) {
+				System.out.println("Nieprawidłowa kwota.");
+				continue;
+			}
+			BigDecimal kwota = sc.nextBigDecimal();
+			sc.nextLine();
+			
+			System.out.println(kwota + " " + kod + " = "
+					+ waluta.przeliczNaZlote(kwota) + " PLN");
+			
+			System.out.println(kwota + " PLN " + " = "
+					+ waluta.przeliczNaWalute(kwota) + " " + kod);
+		}
+	}
+}

src/main/java/waluty/wersja_xml/PrzelicznikWalutOkno.java

+package waluty.wersja_xml;
+
+import java.awt.Color;
+import java.awt.EventQueue;
+import java.awt.Font;
+import java.awt.event.ActionEvent;
+import java.awt.event.ActionListener;
+import java.math.BigDecimal;
+import java.time.LocalDate;
+
+import javax.swing.ButtonGroup;
+import javax.swing.DefaultComboBoxModel;
+import javax.swing.GroupLayout;
+import javax.swing.GroupLayout.Alignment;
+import javax.swing.JButton;
+import javax.swing.JComboBox;
+import javax.swing.JFrame;
+import javax.swing.JLabel;
+import javax.swing.JPanel;
+import javax.swing.JRadioButton;
+import javax.swing.JTextField;
+import javax.swing.LayoutStyle.ComponentPlacement;
+import javax.swing.SwingConstants;
+import javax.swing.SwingUtilities;
+import javax.swing.SwingWorker;
+
+public class PrzelicznikWalutOkno {
+	
+	private static final Font FONT_LABEL = new Font("Times New Roman", Font.PLAIN, 24);
+	private static final Font FONT_WARTOSC = new Font("Dialog", Font.BOLD, 24);
+	private static final Font FONT_TXT = new Font("Dialog", Font.BOLD, 32);
+	private static final Font FONT_WYNIK = new Font("Dialog", Font.BOLD, 32);	
+	private static final Font FONT_BUTTON = new Font("Dialog", Font.BOLD, 28);
+
+	private Tabela tabela = null;
+	private JFrame frmPrzelicznikWalut;
+	private JTextField txtKwota;
+	private JComboBox<String> comboBox_Waluta;
+	private JLabel lbl_KodWaluty;
+	private JLabel lbl_NazwaWaluty;
+	private JLabel lbl_KursWaluty;
+	private JRadioButton rdbtnWalutaNaZlote;
+	private JRadioButton rdbtnZloteNaWalute;
+	private JButton btnPrzelicz;
+	private JLabel lblPrawdziwyWynik;
+	private final ButtonGroup buttonGroup = new ButtonGroup();
+	private JPanel panel_1;
+	private JLabel lblTabela;
+	private JLabel lbl_NumerTabeli;
+	private JLabel lblData;
+	private JLabel lbl_DataTabeli;
+	private JTextField txtData;
+	private JButton btnPobierzAktualne;
+
+	/**
+	 * Launch the application.
+	 */
+	public static void main(String[] args) {
+		EventQueue.invokeLater(new Runnable() {
+			public void run() {
+				try {
+					PrzelicznikWalutOkno window = new PrzelicznikWalutOkno();
+					window.txtData.setText(LocalDate.now().toString());
+					window.frmPrzelicznikWalut.setVisible(true);
+					window.pobierzAktualneKursy();
+				} catch (Exception e) {
+					e.printStackTrace();
+				}
+			}
+		});
+	}
+
+	/**
+	 * Create the application.
+	 */
+	public PrzelicznikWalutOkno() {
+		initialize();
+	}
+
+	/**
+	 * Initialize the contents of the frame.
+	 */
+	private void initialize() {
+		frmPrzelicznikWalut = new JFrame();
+		frmPrzelicznikWalut.setTitle("Przelicznik Walut");
+		frmPrzelicznikWalut.setBounds(100, 100, 480, 701);
+		frmPrzelicznikWalut.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
+		
+		JLabel lblWybierzWalut = new JLabel("Wybierz walutę");
+		lblWybierzWalut.setFont(FONT_LABEL);
+		
+		comboBox_Waluta = new JComboBox<>();
+		comboBox_Waluta.addActionListener(new ActionListener() {
+			public void actionPerformed(ActionEvent ev) {
+				wyswietlDaneWaluty();
+			}
+		});
+		comboBox_Waluta.setModel(
+				new DefaultComboBoxModel<>(new String[] {"--"}));
+		
+		comboBox_Waluta.setFont(FONT_WARTOSC);
+		
+		JPanel panel = new JPanel();
+		
+		txtKwota = new JTextField();
+		txtKwota.addActionListener(new ActionListener() {
+			public void actionPerformed(ActionEvent ev) {
+				przelicz();
+			}
+		});
+		txtKwota.setText("100");
+		txtKwota.setColumns(10);
+		txtKwota.setFont(FONT_TXT);
+		
+		JLabel lblPodajKwot = new JLabel("Podaj kwotę");
+		lblPodajKwot.setFont(FONT_LABEL);
+		
+		rdbtnWalutaNaZlote = new JRadioButton("waluta na złote");
+		rdbtnWalutaNaZlote.addActionListener(new ActionListener() {
+			public void actionPerformed(ActionEvent ev) {
+				przelicz();
+			}
+		});
+		rdbtnWalutaNaZlote.setFont(FONT_LABEL);
+		
+		buttonGroup.add(rdbtnWalutaNaZlote);
+		
+		rdbtnZloteNaWalute = new JRadioButton("złote na walute");
+		rdbtnZloteNaWalute.setFont(FONT_LABEL);
+		rdbtnZloteNaWalute.addActionListener(new ActionListener() {
+			public void actionPerformed(ActionEvent ev) {
+				przelicz();
+			}
+		});
+		buttonGroup.add(rdbtnZloteNaWalute);
+		
+		btnPrzelicz = new JButton("Przelicz");
+		btnPrzelicz.addActionListener(new ActionListener() {
+			public void actionPerformed(ActionEvent ev) {
+				przelicz();
+			}
+		});
+		btnPrzelicz.setFont(FONT_BUTTON);
+		
+		JLabel lblWynik = new JLabel("Wynik");
+		lblWynik.setFont(FONT_LABEL);
+		
+		lblPrawdziwyWynik = new JLabel("0.00");
+		lblPrawdziwyWynik.setFont(FONT_WYNIK);
+		lblPrawdziwyWynik.setForeground(Color.GRAY);
+		
+		panel_1 = new JPanel();
+		
+		JLabel lblPodajDat = new JLabel("Podaj datę");
+		lblPodajDat.setFont(FONT_LABEL);
+		
+		txtData = new JTextField();
+		txtData.setHorizontalAlignment(SwingConstants.CENTER);
+		txtData.setFont(new Font("Dialog", Font.PLAIN, 20));
+		txtData.setText("data");
+		txtData.setColumns(10);
+		
+		JButton btnZmieDat = new JButton("Zmień datę");
+		btnZmieDat.addActionListener(new ActionListener() {
+			public void actionPerformed(ActionEvent e) {
+				pobierzKursyDlaDaty();
+			}
+		});
+		btnZmieDat.setFont(new Font("Dialog", Font.BOLD, 18));
+		
+		btnPobierzAktualne = new JButton("Pobierz aktualne");
+		btnPobierzAktualne.addActionListener(new ActionListener() {
+			public void actionPerformed(ActionEvent e) {
+				pobierzAktualneKursy();
+			}
+		});
+		btnPobierzAktualne.setFont(new Font("Dialog", Font.BOLD, 18));
+		
+		GroupLayout groupLayout = new GroupLayout(frmPrzelicznikWalut.getContentPane());
+		groupLayout.setHorizontalGroup(
+			groupLayout.createParallelGroup(Alignment.LEADING)
+				.addGroup(groupLayout.createSequentialGroup()
+					.addContainerGap()
+					.addGroup(groupLayout.createParallelGroup(Alignment.TRAILING)
+						.addComponent(panel_1, Alignment.LEADING, GroupLayout.DEFAULT_SIZE, 448, Short.MAX_VALUE)
+						.addComponent(btnPrzelicz, Alignment.LEADING, GroupLayout.DEFAULT_SIZE, 448, Short.MAX_VALUE)
+						.addGroup(Alignment.LEADING, groupLayout.createSequentialGroup()
+							.addComponent(rdbtnWalutaNaZlote)
+							.addPreferredGap(ComponentPlacement.RELATED, 108, Short.MAX_VALUE)
+							.addComponent(rdbtnZloteNaWalute))
+						.addGroup(Alignment.LEADING, groupLayout.createSequentialGroup()
+							.addComponent(lblPodajKwot)
+							.addPreferredGap(ComponentPlacement.RELATED, 139, Short.MAX_VALUE)
+							.addComponent(txtKwota, GroupLayout.PREFERRED_SIZE, 189, GroupLayout.PREFERRED_SIZE))
+						.addComponent(panel, Alignment.LEADING, GroupLayout.DEFAULT_SIZE, 448, Short.MAX_VALUE)
+						.addComponent(lblWynik, Alignment.LEADING)
+						.addComponent(lblPrawdziwyWynik, Alignment.LEADING)
+						.addGroup(Alignment.LEADING, groupLayout.createSequentialGroup()
+							.addGroup(groupLayout.createParallelGroup(Alignment.TRAILING, false)
+								.addComponent(lblPodajDat, Alignment.LEADING, GroupLayout.DEFAULT_SIZE, GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
+								.addComponent(lblWybierzWalut, Alignment.LEADING, GroupLayout.DEFAULT_SIZE, 223, Short.MAX_VALUE))
+							.addPreferredGap(ComponentPlacement.UNRELATED)
+							.addGroup(groupLayout.createParallelGroup(Alignment.LEADING)
+								.addComponent(txtData, GroupLayout.DEFAULT_SIZE, 207, Short.MAX_VALUE)
+								.addComponent(comboBox_Waluta, 0, 207, Short.MAX_VALUE)))
+						.addGroup(groupLayout.createSequentialGroup()
+							.addComponent(btnPobierzAktualne, GroupLayout.PREFERRED_SIZE, 207, GroupLayout.PREFERRED_SIZE)
+							.addGap(34)
+							.addComponent(btnZmieDat, GroupLayout.DEFAULT_SIZE, 207, Short.MAX_VALUE)))
+					.addContainerGap())
+		);
+		groupLayout.setVerticalGroup(
+			groupLayout.createParallelGroup(Alignment.TRAILING)
+				.addGroup(groupLayout.createSequentialGroup()
+					.addContainerGap()
+					.addComponent(panel_1, GroupLayout.PREFERRED_SIZE, 103, GroupLayout.PREFERRED_SIZE)
+					.addPreferredGap(ComponentPlacement.UNRELATED)
+					.addGroup(groupLayout.createParallelGroup(Alignment.LEADING, false)
+						.addComponent(txtData, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE)
+						.addComponent(lblPodajDat, GroupLayout.DEFAULT_SIZE, GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
+					.addPreferredGap(ComponentPlacement.RELATED)
+					.addGroup(groupLayout.createParallelGroup(Alignment.LEADING)
+						.addComponent(btnZmieDat)
+						.addComponent(btnPobierzAktualne, GroupLayout.PREFERRED_SIZE, 32, GroupLayout.PREFERRED_SIZE))
+					.addPreferredGap(ComponentPlacement.RELATED, 17, Short.MAX_VALUE)
+					.addGroup(groupLayout.createParallelGroup(Alignment.BASELINE)
+						.addComponent(comboBox_Waluta, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE)
+						.addComponent(lblWybierzWalut))
+					.addPreferredGap(ComponentPlacement.UNRELATED)
+					.addComponent(panel, GroupLayout.PREFERRED_SIZE, 142, GroupLayout.PREFERRED_SIZE)
+					.addPreferredGap(ComponentPlacement.UNRELATED)
+					.addGroup(groupLayout.createParallelGroup(Alignment.BASELINE)
+						.addComponent(txtKwota, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE)
+						.addComponent(lblPodajKwot))
+					.addPreferredGap(ComponentPlacement.UNRELATED)
+					.addGroup(groupLayout.createParallelGroup(Alignment.BASELINE)
+						.addComponent(rdbtnWalutaNaZlote)
+						.addComponent(rdbtnZloteNaWalute))
+					.addPreferredGap(ComponentPlacement.RELATED)
+					.addComponent(btnPrzelicz)
+					.addPreferredGap(ComponentPlacement.UNRELATED)
+					.addComponent(lblWynik)
+					.addPreferredGap(ComponentPlacement.UNRELATED)
+					.addComponent(lblPrawdziwyWynik)
+					.addGap(33))
+		);
+		
+		lblTabela = new JLabel("Tabela");
+		lblTabela.setFont(FONT_LABEL);
+		
+		lbl_NumerTabeli = new JLabel("?");
+		lbl_NumerTabeli.setFont(new Font("Dialog", Font.BOLD, 24));
+		
+		lblData = new JLabel("Data:");
+		lblData.setFont(FONT_LABEL);
+		
+		lbl_DataTabeli = new JLabel("?");
+		lbl_DataTabeli.setFont(new Font("Dialog", Font.BOLD, 24));
+		
+		GroupLayout gl_panel_1 = new GroupLayout(panel_1);
+		gl_panel_1.setHorizontalGroup(
+			gl_panel_1.createParallelGroup(Alignment.LEADING)
+				.addGroup(gl_panel_1.createSequentialGroup()
+					.addContainerGap()
+					.addGroup(gl_panel_1.createParallelGroup(Alignment.LEADING)
+						.addGroup(gl_panel_1.createSequentialGroup()
+							.addComponent(lblTabela, GroupLayout.PREFERRED_SIZE, 95, GroupLayout.PREFERRED_SIZE)
+							.addGap(18)
+							.addComponent(lbl_NumerTabeli, GroupLayout.PREFERRED_SIZE, 311, GroupLayout.PREFERRED_SIZE))
+						.addGroup(gl_panel_1.createSequentialGroup()
+							.addComponent(lblData, GroupLayout.PREFERRED_SIZE, 95, GroupLayout.PREFERRED_SIZE)
+							.addGap(18)
+							.addComponent(lbl_DataTabeli, GroupLayout.PREFERRED_SIZE, 311, GroupLayout.PREFERRED_SIZE)))
+					.addContainerGap(GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
+		);
+		gl_panel_1.setVerticalGroup(
+			gl_panel_1.createParallelGroup(Alignment.LEADING)
+				.addGroup(gl_panel_1.createSequentialGroup()
+					.addContainerGap()
+					.addGroup(gl_panel_1.createParallelGroup(Alignment.LEADING)
+						.addComponent(lblTabela, GroupLayout.PREFERRED_SIZE, 29, GroupLayout.PREFERRED_SIZE)
+						.addComponent(lbl_NumerTabeli, GroupLayout.PREFERRED_SIZE, 29, GroupLayout.PREFERRED_SIZE))
+					.addGap(12)
+					.addGroup(gl_panel_1.createParallelGroup(Alignment.LEADING)
+						.addComponent(lblData, GroupLayout.PREFERRED_SIZE, 29, GroupLayout.PREFERRED_SIZE)
+						.addComponent(lbl_DataTabeli, GroupLayout.PREFERRED_SIZE, 29, GroupLayout.PREFERRED_SIZE))
+					.addContainerGap(21, Short.MAX_VALUE))
+		);
+		panel_1.setLayout(gl_panel_1);
+		
+		JLabel lblKod = new JLabel("Kod:");
+		lblKod.setFont(FONT_LABEL);
+		
+		JLabel lblNazwa = new JLabel("Nazwa:");
+		lblNazwa.setFont(FONT_LABEL);
+		
+		JLabel lblKurs = new JLabel("Kurs:");
+		lblKurs.setFont(FONT_LABEL);
+		
+		lbl_KodWaluty = new JLabel("kod");
+		lbl_KodWaluty.setFont(FONT_WARTOSC);
+		
+		lbl_NazwaWaluty = new JLabel("nazwa");
+		lbl_NazwaWaluty.setFont(FONT_WARTOSC);
+		
+		lbl_KursWaluty = new JLabel("1.0000");
+		lbl_KursWaluty.setFont(FONT_WARTOSC);
+
+		GroupLayout gl_panel = new GroupLayout(panel);
+		gl_panel.setHorizontalGroup(
+			gl_panel.createParallelGroup(Alignment.LEADING)
+				.addGroup(gl_panel.createSequentialGroup()
+					.addContainerGap()
+					.addGroup(gl_panel.createParallelGroup(Alignment.LEADING, false)
+						.addComponent(lblKurs, Alignment.TRAILING, GroupLayout.DEFAULT_SIZE, GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
+						.addComponent(lblNazwa, Alignment.TRAILING, GroupLayout.DEFAULT_SIZE, GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
+						.addComponent(lblKod, Alignment.TRAILING, GroupLayout.DEFAULT_SIZE, 95, Short.MAX_VALUE))
+					.addPreferredGap(ComponentPlacement.RELATED, 18, GroupLayout.PREFERRED_SIZE)
+					.addGroup(gl_panel.createParallelGroup(Alignment.LEADING)
+						.addComponent(lbl_KodWaluty, Alignment.TRAILING, GroupLayout.DEFAULT_SIZE, 171, Short.MAX_VALUE)
+						.addComponent(lbl_NazwaWaluty, Alignment.TRAILING, GroupLayout.DEFAULT_SIZE, 171, Short.MAX_VALUE)
+						.addComponent(lbl_KursWaluty, Alignment.TRAILING, GroupLayout.DEFAULT_SIZE, 171, Short.MAX_VALUE))
+					.addContainerGap())
+		);
+		gl_panel.setVerticalGroup(
+			gl_panel.createParallelGroup(Alignment.LEADING)
+				.addGroup(gl_panel.createSequentialGroup()
+					.addContainerGap()
+					.addGroup(gl_panel.createParallelGroup(Alignment.BASELINE)
+						.addComponent(lblKod)
+						.addComponent(lbl_KodWaluty))
+					.addPreferredGap(ComponentPlacement.UNRELATED)
+					.addGroup(gl_panel.createParallelGroup(Alignment.BASELINE)
+						.addComponent(lblNazwa)
+						.addComponent(lbl_NazwaWaluty))
+					.addPreferredGap(ComponentPlacement.UNRELATED)
+					.addGroup(gl_panel.createParallelGroup(Alignment.BASELINE)
+						.addComponent(lblKurs)
+						.addComponent(lbl_KursWaluty))
+					.addContainerGap(61, Short.MAX_VALUE))
+		);
+		panel.setLayout(gl_panel);
+		frmPrzelicznikWalut.getContentPane().setLayout(groupLayout);
+	}
+	
+	protected void przelicz() {
+		try {
+			BigDecimal kwota = new BigDecimal(txtKwota.getText());
+			String kod = "" + comboBox_Waluta.getSelectedItem();
+			Waluta waluta = tabela.znajdz(kod);
+			BigDecimal wynik = null;
+			if(rdbtnWalutaNaZlote.isSelected()) {
+				wynik = waluta.przeliczNaZlote(kwota);
+			}
+			if(rdbtnZloteNaWalute.isSelected()) {
+				wynik = waluta.przeliczNaWalute(kwota);
+			}
+			lblPrawdziwyWynik.setText("" + wynik);
+			lblPrawdziwyWynik.setForeground(Color.BLUE);
+		} catch (Exception e) {
+			lblPrawdziwyWynik.setText("błąd");
+			lblPrawdziwyWynik.setForeground(Color.RED);
+		}		
+	}
+
+	protected void wyswietlDaneWaluty() {
+		String kod = "" + comboBox_Waluta.getSelectedItem();
+		Waluta waluta = tabela.znajdz(kod);
+		if(waluta != null) {
+			lbl_KodWaluty.setText(waluta.getKod());
+			lbl_NazwaWaluty.setText(waluta.getNazwa());
+			lbl_KursWaluty.setText("" + waluta.getKurs());
+			if(! txtKwota.getText().isEmpty()) {
+				przelicz();
+			}
+			return;
+		}
+		lblPrawdziwyWynik.setText("0.00");
+		lblPrawdziwyWynik.setForeground(Color.GRAY);
+	}
+
+	private void pobierzAktualneKursy() {
+		// Pobieranie aktualnych kursów w tle (to znaczy w innym wątku)
+		// Aby wykonać operację w tle, w Swingu najlepiej użyć klasy SwingWorker
+		
+		SwingWorker<Void, Void> worker = new SwingWorker<Void, Void>() {
+			protected Void doInBackground() {
+				tabela = ObslugaNBP.pobierzBiezaceKursy();
+				return null;
+			}
+			
+			protected void done() {
+				// tu piszemy "co ma zrobić okno, gdy operacja jest zakończona"
+				// to będzie wykonane przez wątek EDT
+				odswiezDaneTabeli();
+				wyswietlDaneWaluty();
+			}
+		};
+		
+		worker.execute();
+	}
+
+	private void pobierzKursyDlaDaty() {
+		SwingWorker<Void, Void> worker = new SwingWorker<Void, Void>() {
+			protected Void doInBackground() throws Exception {
+				
+				String data = txtData.getText();
+				Tabela nowaTabela = ObslugaNBP.pobierzKursyHistoryczne(data);
+				if(nowaTabela != null) {
+					tabela = nowaTabela;
+					SwingUtilities.invokeLater(() -> {
+						txtData.setForeground(Color.BLACK);
+					});
+				} else {
+					SwingUtilities.invokeLater(() -> {
+						txtData.setForeground(Color.RED);
+					});
+				}
+				return null;
+			}
+			
+			protected void done() {
+				odswiezDaneTabeli();
+				wyswietlDaneWaluty();
+			}
+		};
+		
+		worker.execute();
+	}
+
+	private void odswiezDaneTabeli() {
+		lbl_NumerTabeli.setText(tabela.getNumerTabeli());
+		lbl_DataTabeli.setText("" + tabela.getData());
+		comboBox_Waluta.setModel(new DefaultComboBoxModel<>(tabela.getKodyWalut()));
+	}
+}
\ No newline at end of file

src/main/java/waluty/wersja_xml/Tabela.java

+package waluty.wersja_xml;
+
+import java.time.LocalDate;
+import java.util.Collection;
+import java.util.Map;
+import java.util.TreeMap;
+
+public class Tabela {
+	private final String nazwaTabeli;
+	private final String numerTabeli;
+	private final LocalDate data;
+	private final Map<String, Waluta> waluty = new TreeMap<>();
+	
+	public Tabela() {
+		nazwaTabeli = null;
+		numerTabeli = null;
+		data = null;
+	}
+
+	public Tabela(String nazwaTabeli, String numerTabeli, LocalDate data) {
+		this.nazwaTabeli = nazwaTabeli;
+		this.numerTabeli = numerTabeli;
+		this.data = data;
+	}
+
+	public String getNazwaTabeli() {
+		return nazwaTabeli;
+	}
+
+	public String getNumerTabeli() {
+		return numerTabeli;
+	}
+
+	public LocalDate getData() {
+		return data;
+	}
+
+	@Override
+	public String toString() {
+		return "Tabela " + nazwaTabeli + " nr " + numerTabeli
+				+ " z dnia " + data + " (" + waluty.size() + " walut)";
+	}
+	
+	public void dodaj(Waluta waluta) {
+		waluty.put(waluta.getKod(), waluta);
+	}
+	
+	public Waluta znajdz(String kod) {
+		return waluty.get(kod);
+	}
+	
+	public Collection<Waluta> getWszystkieWaluty() {
+		return waluty.values();
+	}
+	
+	private static final String[] PUSTA_TABLICA = new String[0];
+	
+	public String[] getKodyWalut() {
+		return waluty.keySet().toArray(PUSTA_TABLICA);
+	}
+
+	@Override
+	public int hashCode() {
+		final int prime = 31;
+		int result = 1;
+		result = prime * result + ((data == null) ? 0 : data.hashCode());
+		result = prime * result + ((nazwaTabeli == null) ? 0 : nazwaTabeli.hashCode());
+		result = prime * result + ((numerTabeli == null) ? 0 : numerTabeli.hashCode());
+		result = prime * result + ((waluty == null) ? 0 : waluty.hashCode());
+		return result;
+	}
+
+	@Override
+	public boolean equals(Object obj) {
+		if(this == obj)
+			return true;
+		if(obj == null)
+			return false;
+		if(getClass() != obj.getClass())
+			return false;
+		Tabela other = (Tabela) obj;
+		if(data == null) {
+			if(other.data != null)
+				return false;
+		} else if(!data.equals(other.data))
+			return false;
+		if(nazwaTabeli == null) {
+			if(other.nazwaTabeli != null)
+				return false;
+		} else if(!nazwaTabeli.equals(other.nazwaTabeli))
+			return false;
+		if(numerTabeli == null) {
+			if(other.numerTabeli != null)
+				return false;
+		} else if(!numerTabeli.equals(other.numerTabeli))
+			return false;
+		if(waluty == null) {
+			if(other.waluty != null)
+				return false;
+		} else if(!waluty.equals(other.waluty))
+			return false;
+		return true;
+	}
+}

src/main/java/waluty/wersja_xml/WypiszKursyHistoryczne.java

+package waluty.wersja_xml;
+
+import java.util.Scanner;
+
+public class WypiszKursyHistoryczne {
+
+	public static void main(String[] args) {
+		Scanner sc = new Scanner(System.in);
+		System.out.print("Podaj datę: ");
+		String data = sc.nextLine();
+		
+		System.out.println("Pobieram...");
+		Tabela tabela = ObslugaNBP.pobierzKursyHistoryczne(data);
+		System.out.println("Pobrana tabela: " + tabela);
+		
+		for (Waluta waluta : tabela.getWszystkieWaluty()) {
+			System.out.println(waluta);
+		}
+	}
+
+}

src/main/java/waluty/wersja_xml/WypiszWszystkieWaluty.java

+package waluty.wersja_xml;
+
+import java.util.Collection;
+
+public class WypiszWszystkieWaluty {
+
+	public static void main(String[] args) {
+		Tabela tabela = ObslugaNBP.pobierzBiezaceKursy();		
+		System.out.println("Pobrana tabela: " + tabela);
+		
+		Collection<Waluta> waluty = tabela.getWszystkieWaluty();
+		for (Waluta waluta : waluty) {
+			System.out.println(waluta);
+		}
+	}
+
+}