waluty - początek

src/main/java/waluty/TabelaWalut.java

+package waluty;
+
+import java.time.LocalDate;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+import java.util.Optional;
+
+public class TabelaWalut {
+	private final String no;
+	private final LocalDate effectiveDate;
+	private final List<Waluta> rates = new ArrayList<>();
+	
+	public TabelaWalut(String no, LocalDate effectiveDate) {
+		this.no = no;
+		this.effectiveDate = effectiveDate;
+	}
+	
+    public TabelaWalut(String no, String effectiveDate) {
+        this(no, LocalDate.parse(effectiveDate));
+    }
+    
+    public void addRate(Waluta waluta) {
+        rates.add(waluta);
+    }
+
+    public String getNo() {
+        return no;
+    }
+
+    public LocalDate getEffectiveDate() {
+        return effectiveDate;
+    }
+
+    public List<Waluta> getRates() {
+        // dostęp tylko do odczytu
+        return Collections.unmodifiableList(rates);
+    }
+    
+    @Override
+    public String toString() {
+        return "Tabela nr " + no + " z dnia " + effectiveDate + ", " + rates.size() + " walut";
+    }
+
+    public Optional<Waluta> findByCode(String code) {
+        for(Waluta waluta : rates) {
+            if(waluta.getCode().equals(code) ) {
+                return Optional.of(waluta);
+            }
+        }
+        return Optional.empty();
+    }
+
+    public String[] codes() {
+        return rates.stream()
+        		.map(Waluta::getCode)
+        		.toArray(String[]::new);
+    }
+
+}

src/main/java/waluty/Waluta.java

+package waluty;
+
+import java.math.BigDecimal;
+import java.math.RoundingMode;
+
+public class Waluta {
+	private final String code;
+	private final String currency;
+	private final BigDecimal mid;
+	
+	public Waluta(String code, String currency, BigDecimal mid) {
+		this.code = code;
+		this.currency = currency;
+		this.mid = mid;
+	}
+	
+	public String getCode() {
+		return code;
+	}
+
+	public String getCurrency() {
+		return currency;
+	}
+
+	public BigDecimal getMid() {
+		return mid;
+	}
+
+	@Override
+	public String toString() {
+		return code + " (" + currency + "): " + mid;
+	}
+	
+	public BigDecimal przeliczNaZlote(BigDecimal kwota) {
+		return kwota.multiply(mid).setScale(2, RoundingMode.HALF_EVEN);
+	}
+	
+	public BigDecimal przeliczNaWalute(BigDecimal kwota) {
+		return kwota.divide(mid, 2, RoundingMode.HALF_EVEN);
+	}
+
+}