# Replace usage of JUnit#ThrowingSupplier with own implementation

Author: Bios-Marcel

client/src/main/java/com/msc/serverbrowser/util/basic/OptionalUtility.java

@@ -4,8 +4,6 @@
 import java.util.Optional;
 import java.util.function.Supplier;
 
-import org.junit.jupiter.api.function.ThrowingSupplier;
-
 /**
  * Contains methods for working with {@link Optional}.
  *

client/src/main/java/com/msc/serverbrowser/util/basic/ThrowingSupplier.java

@@ -0,0 +1,21 @@
+package com.msc.serverbrowser.util.basic;
+
+import java.util.function.Supplier;
+
+/**
+ * Serves the same purpose as Javas {@link Supplier}, but it its {@link #get()} function may always
+ * throw a {@link Throwable}.
+ *
+ * @author Marcel
+ * @since 01.03.2018
+ * @param <T> Type of return value
+ */
+@FunctionalInterface
+public interface ThrowingSupplier<T> {
+
+	/**
+	 * @return the return value of Type T returned by the given implementatiom
+	 * @throws Throwable Any exceptions which might be thrown by the implementation
+	 */
+	T get() throws Throwable;
+}

client/src/main/java/com/msc/serverbrowser/util/samp/GTAController.java

@@ -42,7 +42,7 @@ public final class GTAController {
 	/**
 	 * Holds the users username.
 	 */
-	public static StringProperty usernameProperty = new SimpleStringProperty(retrieveUsernameFromRegistry());
+	public static StringProperty usernameProperty = new SimpleStringProperty(retrieveUsernameFromRegistry().orElse(""));
 
 	private GTAController() {
 		// Constructor to prevent instantiation
@@ -53,11 +53,17 @@ private GTAController() {
 	 */
 	public static void applyUsername() {
 		if (!OSUtility.isWindows()) {
+			// TODO Localize
+			final Alert alert = new Alert(AlertType.ERROR, "The feature you are trying to use is not available on your operating system.", ButtonType.OK);
+			Client.insertAlertOwner(alert);
+			alert.setTitle("Apply username");
+			alert.showAndWait();
 			return;
 		}
 
 		killSAMP();
-		PastUsernames.addPastUsername(retrieveUsernameFromRegistry());
+		retrieveUsernameFromRegistry().ifPresent(PastUsernames::addPastUsername);
+
 		try {
 			WindowsRegistry.getInstance().writeStringValue(HKey.HKCU, "SOFTWARE\\SAMP", "PlayerName", usernameProperty.get());
 		}
@@ -73,17 +79,17 @@ public static void applyUsername() {
 	 *
 	 * @return Username or "404 name not found"
 	 */
-	static String retrieveUsernameFromRegistry() {
+	protected static Optional<String> retrieveUsernameFromRegistry() {
 		if (!OSUtility.isWindows()) {
-			return "You are on Linux ;D";
+			return Optional.empty();
 		}
 
 		try {
-			return WindowsRegistry.getInstance().readString(HKey.HKCU, "SOFTWARE\\SAMP", "PlayerName");
+			return Optional.ofNullable(WindowsRegistry.getInstance().readString(HKey.HKCU, "SOFTWARE\\SAMP", "PlayerName"));
 		}
 		catch (final RegistryException exception) {
 			Logging.warn("Couldn't retrieve Username from registry.", exception);
-			return "404 Name not found";
+			return Optional.empty();
 		}
 	}
 

client/src/main/java/com/msc/serverbrowser/util/samp/SAMPLauncher.java

@@ -123,7 +123,7 @@ private static List<String> buildLaunchingArguments(final String address, final
 		arguments.add("-n");
 
 		// TODO Solve better
-		arguments.add(Optional.ofNullable(GTAController.retrieveUsernameFromRegistry()).orElse("CHOOSE_NAME"));
+		arguments.add(GTAController.retrieveUsernameFromRegistry().orElse("CHOOSE_NAME"));
 
 		passwordOptional.ifPresent(password -> {
 			if (!password.isEmpty()) {