introduce currencyrate to hold fiat rate

src/main/java/com/sparrowwallet/sparrow/AppController.java

@@ -104,7 +104,7 @@ public class AppController implements Initializable {
 
     private static Map<Integer, Double> targetBlockFeeRates;
 
-    private static Map<Currency, Double> fiatCurrencyExchangeRate;
+    private static CurrencyRate fiatCurrencyExchangeRate;
 
     @Override
     public void initialize(URL location, ResourceBundle resources) {
@@ -397,7 +397,7 @@ public class AppController implements Initializable {
         return targetBlockFeeRates;
     }
 
-    public static Map<Currency, Double> getFiatCurrencyExchangeRate() {
+    public static CurrencyRate getFiatCurrencyExchangeRate() {
         return fiatCurrencyExchangeRate;
     }
 
@@ -879,6 +879,6 @@ public class AppController implements Initializable {
 
     @Subscribe
     public void exchangeRatesUpdated(ExchangeRatesUpdatedEvent event) {
-        fiatCurrencyExchangeRate = Map.of(event.getSelectedCurrency(), event.getRate());
+        fiatCurrencyExchangeRate = event.getCurrencyRate();
     }
 }

src/main/java/com/sparrowwallet/sparrow/CurrencyRate.java

@@ -0,0 +1,25 @@
+package com.sparrowwallet.sparrow;
+
+import java.util.Currency;
+
+public class CurrencyRate {
+    private final Currency currency;
+    private final Double btcRate;
+
+    public CurrencyRate(Currency currency, Double btcRate) {
+        this.currency = currency;
+        this.btcRate = btcRate;
+    }
+
+    public Currency getCurrency() {
+        return currency;
+    }
+
+    public boolean isAvailable() {
+        return btcRate != null && btcRate > 0.0;
+    }
+
+    public Double getBtcRate() {
+        return btcRate;
+    }
+}

src/main/java/com/sparrowwallet/sparrow/control/FiatLabel.java

@@ -1,6 +1,7 @@
 package com.sparrowwallet.sparrow.control;
 
 import com.sparrowwallet.drongo.protocol.Transaction;
+import com.sparrowwallet.sparrow.CurrencyRate;
 import javafx.beans.property.*;
 import javafx.scene.control.ContextMenu;
 import javafx.scene.control.MenuItem;
@@ -70,6 +71,10 @@ public class FiatLabel extends CopyableLabel {
         this.currencyProperty.set(currency);
     }
 
+    public final void set(CurrencyRate currencyRate, long value) {
+        set(currencyRate.getCurrency(), currencyRate.getBtcRate(), value);
+    }
+
     public final void set(Currency currency, double btcRate, long value) {
         setValue(value);
         setBtcRate(btcRate);

src/main/java/com/sparrowwallet/sparrow/event/ExchangeRatesUpdatedEvent.java

@@ -1,21 +1,27 @@
 package com.sparrowwallet.sparrow.event;
 
+import com.sparrowwallet.sparrow.CurrencyRate;
+
 import java.util.Currency;
 
 public class ExchangeRatesUpdatedEvent {
-    private final Currency selectedCurrency;
-    private final Double rate;
+    private final Currency currency;
+    private final Double btcRate;
 
-    public ExchangeRatesUpdatedEvent(Currency selectedCurrency, Double rate) {
-        this.selectedCurrency = selectedCurrency;
-        this.rate = rate;
+    public ExchangeRatesUpdatedEvent(Currency currency, Double btcRate) {
+        this.currency = currency;
+        this.btcRate = btcRate;
     }
 
-    public Currency getSelectedCurrency() {
-        return selectedCurrency;
+    public Currency getCurrency() {
+        return currency;
     }
 
-    public Double getRate() {
-        return rate;
+    public Double getBtcRate() {
+        return btcRate;
+    }
+
+    public CurrencyRate getCurrencyRate() {
+        return new CurrencyRate(currency, btcRate);
     }
 }

src/main/java/com/sparrowwallet/sparrow/wallet/TransactionsController.java

@@ -2,6 +2,7 @@ package com.sparrowwallet.sparrow.wallet;
 
 import com.google.common.eventbus.Subscribe;
 import com.sparrowwallet.sparrow.AppController;
+import com.sparrowwallet.sparrow.CurrencyRate;
 import com.sparrowwallet.sparrow.EventManager;
 import com.sparrowwallet.sparrow.control.BalanceChart;
 import com.sparrowwallet.sparrow.control.CoinLabel;
@@ -16,8 +17,6 @@ import javafx.scene.control.TreeItem;
 import javafx.scene.input.MouseEvent;
 
 import java.net.URL;
-import java.util.Currency;
-import java.util.Map;
 import java.util.ResourceBundle;
 
 public class TransactionsController extends WalletFormController implements Initializable {
@@ -61,13 +60,9 @@ public class TransactionsController extends WalletFormController implements Init
         });
     }
 
-    private void setFiatBalance(Map<Currency, Double> fiatCurrencyExchangeRate, long balance) {
-        if(fiatCurrencyExchangeRate != null && !fiatCurrencyExchangeRate.isEmpty()) {
-            Currency currency = fiatCurrencyExchangeRate.keySet().iterator().next();
-            Double rate = fiatCurrencyExchangeRate.get(currency);
-            if(rate != null) {
-                fiatBalance.set(currency, rate, balance);
-            }
+    private void setFiatBalance(CurrencyRate currencyRate, long balance) {
+        if(currencyRate != null && currencyRate.isAvailable()) {
+            fiatBalance.set(currencyRate, balance);
         }
     }
 
@@ -124,8 +119,7 @@ public class TransactionsController extends WalletFormController implements Init
 
     @Subscribe
     public void exchangeRatesUpdated(ExchangeRatesUpdatedEvent event) {
-        Map<Currency, Double> fiatRate = Map.of(event.getSelectedCurrency(), event.getRate());
-        setFiatBalance(fiatRate, getWalletForm().getWalletTransactionsEntry().getBalance());
+        setFiatBalance(event.getCurrencyRate(), getWalletForm().getWalletTransactionsEntry().getBalance());
     }
 
     //TODO: Remove