fix examples and name not being used in dirs

Author: Osiris-Team

README.md

@@ -11,15 +11,16 @@ In addition, it is also highly beginner-friendly, making it accessible to everyo
 vertical().add(text("Hello World!"))
 ```
 <details>
-<summary>3 lines example</summary>
+<summary>Minimal example</summary>
 
 ```java
 import com.osiris.desku.App;
 import static com.osiris.desku.Statics;
 public class Main {
     public static void main(String[] args) throws Exception {
-        App.init(new DesktopUIManager());
+        App.uis = new DesktopUIManager(); // Not needed when using the Desku-Gradle-Starter-App
         App.name = "My-App";
+        App.init();
         App.uis.create(() -> {
             return vertical().add(text("Hello World!")); 
         });
@@ -37,9 +38,10 @@ import static com.osiris.desku.Statics; // Low-code Java UI via static methods
 public class Main {
     public static void main(String[] args) throws Exception {
 
-        // Setup app details.
-        App.init(new DesktopUIManager()); // Not needed when using the Desku-Gradle-Starter-App
+        // Setup app details and init.
+        App.uis = new DesktopUIManager(); // Not needed when using the Desku-Gradle-Starter-App
         App.name = "My-App";
+        App.init(); 
 
         // Create routes.
         // This is only for demonstration. 

src/main/java/com/osiris/desku/App.java

@@ -110,6 +110,7 @@ public static void updateDirs(){
      */
     public static Theme theme = new Theme();
 
+
     public static UIManager uis = null;
     public static ExecutorService executor = Executors.newCachedThreadPool();
 
@@ -127,16 +128,25 @@ public LoggerParams() {
         }
     }
 
+    /**
+     * Initialize assuming platform-specific {@link UIManager} was already set earlier. <br>
+     * Meaning {@link App#uis} must be not null when calling this.
+     */
+    public static void init() {
+        init(null, new LoggerParams());
+    }
+
     public static void init(UIManager uiManager) {
         init(uiManager, new LoggerParams());
     }
 
     public static void init(UIManager uiManager, LoggerParams loggerParams) {
-        if (uiManager == null) {
+        if (uiManager == null && App.uis == null) {
             throw new NullPointerException("Provided UI factory is null!" +
                     " Make sure to provide an implementation for the platform this app is running in.");
         }
-        App.uis = uiManager;
+        if(uiManager != null)
+            App.uis = uiManager;
         try {
             updateDirs();
             Logger.getGlobal().setLevel(Level.SEVERE);

src/test/java/com/osiris/desku/simple_app/AppTest.java

@@ -10,10 +10,10 @@
 class AppTest {
 
     public static void main(String[] args) throws Exception {
-        // Setup details
-        App.init(new DesktopUIManager());
-        App.name = "My-App";
-        // before loading the page
+        // Setup details before init
+        App.uis = new DesktopUIManager();
+        App.name = "My-Example-Desku-App";
+        App.init();
 
         // Create routes
         Route home = new Home();