Show one Address component per address so the pane stays in step with the person's list.

A second component of the same class is a new injected instance, leaving the cached singleton in place, and selection stays an attribute of the person.

Co-authored-by: Cursor <cursoragent@cursor.com>

fx/src/main/java/de/neitzel/fx/view/BindingList.java

@@ -11,8 +11,8 @@ import java.util.Map;
 /**
  * The list of binding elements declared inside {@code fx:define}.
  * <p>
- * The list is not a scene-graph child. FXML adds each {@link DirectBinding} or
- * {@link ComputedBinding} child to {@link #getElements()}.
+ * The list is not a scene-graph child. FXML adds each {@link DirectBinding},
+ * {@link ComputedBinding}, or {@link Repeat} child to {@link #getElements()}.
  */
 @DefaultProperty("elements")
 public class BindingList {
@@ -29,8 +29,8 @@ public class BindingList {
     /**
      * Returns the binding elements in this list.
      * <p>
-     * FXML appends child elements to the returned list. A child is a {@link DirectBinding} or a
-     * {@link ComputedBinding}.
+     * FXML appends child elements to the returned list. A child is a {@link DirectBinding}, a
+     * {@link ComputedBinding}, or a {@link Repeat}.
      *
      * @return the mutable list of binding elements
      */
@@ -54,6 +54,8 @@ public class BindingList {
                 DirectBindingApplier.apply(namespace, viewModel, directBinding, context);
             } else if (element instanceof ComputedBinding computedBinding) {
                 ComputedBindingApplier.apply(namespace, viewModel, controller, root, computedBinding);
+            } else if (element instanceof Repeat repeat) {
+                RepeatApplier.apply(namespace, viewModel, repeat, context);
             } else {
                 throw new IllegalArgumentException("Not a binding element: " + element);
             }

fx/src/main/java/de/neitzel/fx/view/Components.java

@@ -31,7 +31,9 @@ final class Components {
      * <p>
      * An unknown type, such as a JavaFX control, makes {@link ApplicationContext#getComponent}
      * throw {@link IllegalArgumentException}. This method returns null so FXML constructs that
-     * type itself. A failure while creating a known Component is not caught.
+     * type itself. A failure while creating a known Component is not caught. The first Component
+     * of a class in one load is the cached singleton. A second Component of that class is a new
+     * injected instance, so the document can show two of them.
      *
      * @param type    the type FXML is about to construct
      * @param context the container that creates Components
@@ -44,7 +46,38 @@ final class Components {
         } catch (IllegalArgumentException notAComponent) {
             return null;
         }
-        return () -> load(component, context);
+        if (!LoadSession.claimFirst(type)) {
+            component = context.createComponent(type);
+        }
+        Object created = component;
+        return () -> load(created, context);
+    }
+
+    /**
+     * Creates a new Component and loads its document.
+     * <p>
+     * The instance is not the cached singleton. Its dependencies still come from
+     * {@link ApplicationContext#getComponent}. Bindings wait until {@link #setModel} runs.
+     *
+     * @param type    the Component class
+     * @param context the container that creates the instance and its dependencies
+     * @return the loaded Component
+     */
+    static Object fresh(Class<?> type, ApplicationContext context) {
+        Object component = context.createComponent(type.asSubclass(Object.class));
+        return load(component, context);
+    }
+
+    /**
+     * Sets the Component's model property.
+     * <p>
+     * A non-null value selects the ViewModel and then runs the Component's bindings.
+     *
+     * @param component the Component
+     * @param model     the Model instance
+     */
+    static void setModel(Object component, Object model) {
+        modelProperty(component).setValue(model);
     }
 
     private static Object load(Object component, ApplicationContext context) {

fx/src/main/java/de/neitzel/fx/view/LoadSession.java

@@ -3,7 +3,9 @@ package de.neitzel.fx.view;
 import java.util.ArrayDeque;
 import java.util.ArrayList;
 import java.util.Deque;
+import java.util.HashSet;
 import java.util.List;
+import java.util.Set;
 
 /**
  * Holds the binding lists instantiated while one View is loading.
@@ -18,6 +20,7 @@ final class LoadSession {
     private static final ThreadLocal<Deque<LoadSession>> STACK = new ThreadLocal<>();
 
     private final List<BindingList> bindingLists = new ArrayList<>();
+    private final Set<Class<?>> built = new HashSet<>();
 
     private LoadSession() {
     }
@@ -39,20 +42,33 @@ final class LoadSession {
      * Opens a nested session for a Component document.
      * <p>
      * Binding lists created until {@link #unnest()} register here, not on the parent session.
+     * A Component created after the parent load has finished, such as a repeated child added
+     * later, still gets a session so its own binding list can be captured.
      *
      * @return the nested session
      */
     static LoadSession nest() {
+        Deque<LoadSession> stack = STACK.get();
+        if (stack == null) {
+            stack = new ArrayDeque<>();
+            STACK.set(stack);
+        }
         LoadSession session = new LoadSession();
-        STACK.get().push(session);
+        stack.push(session);
         return session;
     }
 
     /**
      * Restores the session that was current before {@link #nest()}.
+     * <p>
+     * When the nested session was the only one, the thread-local stack is dropped.
      */
     static void unnest() {
-        STACK.get().pop();
+        Deque<LoadSession> stack = STACK.get();
+        stack.pop();
+        if (stack.isEmpty()) {
+            STACK.remove();
+        }
     }
 
     /**
@@ -75,6 +91,23 @@ final class LoadSession {
         stack.peek().bindingLists.add(bindingList);
     }
 
+    /**
+     * Records the first Component of {@code type} built during this load.
+     * <p>
+     * Nested documents share the outermost session, so a second Component of the same class
+     * anywhere in the load is not the first.
+     *
+     * @param type the Component class
+     * @return {@code true} when this is the first time that class is built during the load
+     */
+    static boolean claimFirst(Class<?> type) {
+        Deque<LoadSession> stack = STACK.get();
+        if (stack == null || stack.isEmpty()) {
+            return true;
+        }
+        return stack.peekLast().built.add(type);
+    }
+
     /**
      * Returns the lists registered during this session, in document order.
      *

fx/src/main/java/de/neitzel/fx/view/Repeat.java

@@ -0,0 +1,69 @@
+package de.neitzel.fx.view;
+
+/**
+ * A repeat element declared in a {@link BindingList}.
+ * <p>
+ * The element names the pane by {@code fx:id}, the Component class, and the collection
+ * Attribute. The library keeps one Component child in that pane for each Model instance, in
+ * list order.
+ */
+public class Repeat {
+
+    private String pane;
+    private String component;
+    private String collection;
+
+    /**
+     * Sets the {@code fx:id} of the pane that holds the Component children.
+     *
+     * @param pane the pane id
+     */
+    public void setPane(String pane) {
+        this.pane = pane;
+    }
+
+    /**
+     * Sets the Component class name. Each element gets a new instance of that class.
+     *
+     * @param component the class name
+     */
+    public void setComponent(String component) {
+        this.component = component;
+    }
+
+    /**
+     * Sets the collection Attribute name. The list holds the Model instances.
+     *
+     * @param collection the attribute name
+     */
+    public void setCollection(String collection) {
+        this.collection = collection;
+    }
+
+    /**
+     * Returns the {@code fx:id} of the pane.
+     *
+     * @return the pane id
+     */
+    public String getPane() {
+        return pane;
+    }
+
+    /**
+     * Returns the Component class name.
+     *
+     * @return the class name
+     */
+    public String getComponent() {
+        return component;
+    }
+
+    /**
+     * Returns the collection Attribute name.
+     *
+     * @return the attribute name
+     */
+    public String getCollection() {
+        return collection;
+    }
+}

fx/src/main/java/de/neitzel/fx/view/RepeatApplier.java

@@ -0,0 +1,83 @@
+package de.neitzel.fx.view;
+
+import de.neitzel.injection.ApplicationContext;
+import javafx.beans.property.Property;
+import javafx.collections.ListChangeListener;
+import javafx.collections.ObservableList;
+import javafx.scene.Node;
+import javafx.scene.layout.Pane;
+
+import java.util.Map;
+
+/**
+ * Keeps one Component child in a pane for each Model instance in a collection.
+ */
+final class RepeatApplier {
+
+    private RepeatApplier() {
+    }
+
+    /**
+     * Fills the named pane with one new Component for each element, in list order.
+     * <p>
+     * Each Component is a new injected instance. The cached singleton of that class is left
+     * in place. The child's model property is the element. Adding or removing an element
+     * adds or removes the matching child. The list is the one the entity holds, so a change
+     * on either side is visible in the pane.
+     *
+     * @param namespace objects addressed by {@code fx:id}
+     * @param viewModel the ViewModel for this View
+     * @param repeat    the declaration
+     * @param context   the container that creates each Component
+     */
+    static void apply(Map<String, Object> namespace, ViewModel viewModel, Repeat repeat,
+                      ApplicationContext context) {
+        Object named = namespace.get(repeat.getPane());
+        if (!(named instanceof Pane pane)) {
+            throw new IllegalArgumentException("No pane \"" + repeat.getPane() + "\"");
+        }
+        Property<?> property = viewModel.property(repeat.getCollection());
+        if (property == null || !(property.getValue() instanceof ObservableList<?> values)) {
+            throw new IllegalArgumentException("No collection \"" + repeat.getCollection() + "\"");
+        }
+        Class<?> type = componentType(repeat.getComponent());
+        for (Object element : values) {
+            pane.getChildren().add(child(type, context, element));
+        }
+        listen(pane, type, context, values);
+    }
+
+    @SuppressWarnings("unchecked")
+    private static void listen(Pane pane, Class<?> type, ApplicationContext context, ObservableList<?> values) {
+        ObservableList<Object> elements = (ObservableList<Object>) values;
+        elements.addListener((ListChangeListener<Object>) change -> {
+            while (change.next()) {
+                if (change.wasPermutated() || change.wasUpdated()) {
+                    continue;
+                }
+                if (change.getRemovedSize() > 0) {
+                    pane.getChildren().remove(change.getFrom(), change.getFrom() + change.getRemovedSize());
+                }
+                for (int index = 0; index < change.getAddedSize(); index++) {
+                    pane.getChildren().add(
+                            change.getFrom() + index,
+                            child(type, context, change.getAddedSubList().get(index)));
+                }
+            }
+        });
+    }
+
+    private static Node child(Class<?> type, ApplicationContext context, Object element) {
+        Object component = Components.fresh(type, context);
+        Components.setModel(component, element);
+        return (Node) component;
+    }
+
+    private static Class<?> componentType(String className) {
+        try {
+            return Class.forName(className);
+        } catch (ClassNotFoundException failure) {
+            throw new IllegalArgumentException("No component " + className, failure);
+        }
+    }
+}

fx/src/main/java/de/neitzel/fx/view/ViewLoader.java

@@ -37,11 +37,21 @@ public final class ViewLoader {
      * Attribute, with that Attribute's name as the source. A parent carries a copy with the source
      * extended. It does not fail the load.
      * A parent document names a Component class as an element. The context creates that Component
-     * and injects its services. The Component document {@code ClassName.fxml}, in the same package,
-     * is loaded with the Component as {@code fx:root} and as the Controller. That document's
-     * bindings are not applied during this load. They run when the Component's model property
-     * becomes a non-null Model. A Component that implements {@link HasViewModel} receives that
-     * ViewModel after the property is set and before those bindings run.
+     * and injects its services. A second element of the same class is another injected instance,
+     * and the cached singleton stays the first one. The Component document {@code ClassName.fxml},
+     * in the same package, is loaded with the Component as {@code fx:root} and as the Controller.
+     * That document's bindings are not applied during this load. They run when the Component's
+     * model property becomes a non-null Model. A Component that implements {@link HasViewModel}
+     * receives that ViewModel after the property is set and before those bindings run.
+     * A {@link Repeat} in the same list names a pane, a Component class, and a collection
+     * Attribute. One new Component child is placed in that pane for each Model instance, in list
+     * order. Adding or removing an element updates that pane. Those instances are created with
+     * {@link de.neitzel.injection.ApplicationContext#createComponent} so the cached singleton of
+     * that class stays in place. A collection of Model instances is an
+     * {@link javafx.collections.ObservableList} of those instances, shared with the entity.
+     * Selection is a separate Attribute of the parent Model. Null means nothing is selected.
+     * A Direct binding can tie a control property to that Attribute. The repeated Component does
+     * not store the selection.
      * Loading does not open a popup or fill a status bar. A Direct binding whose path is
      * {@code latestMessage} shows the latest Message text. {@link MessagePopup#showNewMessages}
      * shows each newly added Message in a dialog.

fx/src/main/java/de/neitzel/fx/view/ViewModel.java

@@ -54,11 +54,12 @@ import java.util.function.Consumer;
  * Attribute, stores the ViewModel for the nested Model instance, or null when the Attribute
  * is null. Strings, numbers, booleans, enums, {@link Date}, {@link Calendar}, and {@code java.time}
  * values stay simple even when that type has setters. A collection of Model instances is not a
- * Complex attribute. A list, set, or collection of simple values is an object property whose
- * value is an {@link ObservableList} of those values. When that attribute's current value is a
- * list, the observable list is backed by it and stored on the entity when the setter accepts it,
- * so both sides hold one list. A cycle, or another Attribute that reaches the same instance,
- * reuses that ViewModel.
+ * Complex attribute. It is an object property whose value is an {@link ObservableList} of those
+ * Model instances, not of ViewModels. A list, set, or collection of simple values is an object
+ * property whose value is an {@link ObservableList} of those values. When either attribute's
+ * current value is a list, the observable list is backed by it and stored on the entity when the
+ * setter accepts it, so both sides hold one list. A cycle, or another Attribute that reaches the
+ * same instance, reuses that ViewModel.
  * The property is set from the Attribute when the ViewModel is created. A null number or
  * boolean leaves the primitive property at its default. After that, a change of the property
  * writes the Attribute. A Complex attribute writes the Model instance behind the ViewModel.
@@ -113,7 +114,7 @@ public class ViewModel {
                 properties.put(name, property);
                 complexAttributes.add(name);
             } else {
-                if (isSimpleValueCollection(getter)) {
+                if (isSimpleValueCollection(getter) || isModelCollection(getter)) {
                     current = shareSimpleList(setter, name, current);
                 }
                 Property<?> property = createProperty(type, current);
@@ -545,6 +546,14 @@ public class ViewModel {
         return element != null && isSimpleValue(element);
     }
 
+    private static boolean isModelCollection(Method getter) {
+        if (!Collection.class.isAssignableFrom(getter.getReturnType())) {
+            return false;
+        }
+        Class<?> element = elementType(getter.getGenericReturnType());
+        return element != null && isComplex(element);
+    }
+
     private static Class<?> elementType(Type type) {
         if (!(type instanceof ParameterizedType parameterized) || parameterized.getActualTypeArguments().length != 1) {
             return null;

fx/src/test/java/de/neitzel/fx/view/RepeatAddressComponentsTest.java

@@ -0,0 +1,231 @@
+package de.neitzel.fx.view;
+
+import de.neitzel.fx.view.component.AddressForm;
+import de.neitzel.fx.view.fixture.Address;
+import de.neitzel.fx.view.fixture.Person;
+import de.neitzel.injection.ApplicationContext;
+import javafx.application.Platform;
+import javafx.collections.ObservableList;
+import javafx.scene.control.ComboBox;
+import javafx.scene.control.Label;
+import javafx.scene.control.TextField;
+import javafx.scene.layout.VBox;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+
+import java.net.URL;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicReference;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertInstanceOf;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.junit.jupiter.api.Assertions.assertNotSame;
+import static org.junit.jupiter.api.Assertions.assertNull;
+import static org.junit.jupiter.api.Assertions.assertSame;
+import static org.junit.jupiter.api.Assertions.fail;
+
+class RepeatAddressComponentsTest {
+
+    @BeforeAll
+    static void startJavaFx() throws InterruptedException {
+        CountDownLatch started = new CountDownLatch(1);
+        try {
+            Platform.startup(started::countDown);
+        } catch (IllegalStateException alreadyStarted) {
+            started.countDown();
+        }
+        if (!started.await(10, TimeUnit.SECONDS)) {
+            fail("JavaFX toolkit did not start");
+        }
+    }
+
+    @Test
+    void addressesAreTheAddressInstancesOnTheSharedList() throws Exception {
+        onFx(() -> {
+            Address main = new Address("Main");
+            Address oak = new Address("Oak");
+            Person person = new Person("Ada");
+            person.setAddresses(new ArrayList<>(List.of(main, oak)));
+            URL fxml = RepeatAddressComponentsTest.class.getResource("plain-view.fxml");
+            assertNotNull(fxml);
+            ApplicationContext context = new ApplicationContext("de.neitzel.fx.view.fixture");
+            LoadedView loaded = ViewLoader.load(fxml, person, context);
+            assertInstanceOf(ObservableList.class, loaded.property("addresses").getValue());
+            @SuppressWarnings("unchecked")
+            ObservableList<Address> addresses = (ObservableList<Address>) loaded.property("addresses").getValue();
+            assertSame(main, addresses.get(0));
+            assertSame(oak, addresses.get(1));
+            assertEquals("Main", addresses.get(0).getStreet());
+            assertEquals("Oak", addresses.get(1).getStreet());
+            assertSame(person.getAddresses(), addresses);
+            addresses.add(new Address("Elm"));
+            assertEquals(List.of("Main", "Oak", "Elm"), streets(person.getAddresses()));
+        });
+    }
+
+    @Test
+    void eachAddressAppearsAsItsOwnFormInListOrder() throws Exception {
+        onFx(() -> {
+            Address main = new Address("Main");
+            Address oak = new Address("Oak");
+            Person person = new Person("Ada");
+            person.setAddresses(new ArrayList<>(List.of(main, oak)));
+            URL fxml = RepeatAddressComponentsTest.class.getResource("repeat-addresses.fxml");
+            assertNotNull(fxml);
+            ApplicationContext context = new ApplicationContext("de.neitzel.fx.view.component");
+            AddressForm cached = context.getComponent(AddressForm.class);
+            LoadedView loaded = ViewLoader.load(fxml, person, context);
+            VBox pane = (VBox) loaded.getRoot().lookup("#addressPane");
+            assertEquals(2, pane.getChildren().size());
+            AddressForm first = (AddressForm) pane.getChildren().get(0);
+            AddressForm second = (AddressForm) pane.getChildren().get(1);
+            assertNotSame(first, second);
+            assertNotSame(cached, first);
+            assertNotSame(cached, second);
+            assertSame(cached, context.getComponent(AddressForm.class));
+            assertSame(main, first.getModel());
+            assertSame(oak, second.getModel());
+            assertEquals("Main", ((TextField) first.lookup("#streetField")).getText());
+            assertEquals("Oak", ((TextField) second.lookup("#streetField")).getText());
+            assertEquals("Lane", ((Label) first.lookup("#streetLabel")).getText());
+            assertEquals("Lane", ((Label) second.lookup("#streetLabel")).getText());
+        });
+    }
+
+    @Test
+    void addingAndRemovingAnAddressUpdatesThePaneAndTheEntity() throws Exception {
+        onFx(() -> {
+            Address main = new Address("Main");
+            Address oak = new Address("Oak");
+            Person person = new Person("Ada");
+            person.setAddresses(new ArrayList<>(List.of(main, oak)));
+            URL fxml = RepeatAddressComponentsTest.class.getResource("repeat-addresses.fxml");
+            assertNotNull(fxml);
+            ApplicationContext context = new ApplicationContext("de.neitzel.fx.view.component");
+            LoadedView loaded = ViewLoader.load(fxml, person, context);
+            VBox pane = (VBox) loaded.getRoot().lookup("#addressPane");
+            @SuppressWarnings("unchecked")
+            ObservableList<Address> addresses = (ObservableList<Address>) loaded.property("addresses").getValue();
+            Address elm = new Address("Elm");
+            addresses.add(elm);
+            assertEquals(3, pane.getChildren().size());
+            AddressForm added = (AddressForm) pane.getChildren().get(2);
+            assertSame(elm, added.getModel());
+            assertEquals("Elm", ((TextField) added.lookup("#streetField")).getText());
+            assertEquals(List.of("Main", "Oak", "Elm"), streets(person.getAddresses()));
+            addresses.remove(oak);
+            assertEquals(2, pane.getChildren().size());
+            assertSame(main, ((AddressForm) pane.getChildren().get(0)).getModel());
+            assertSame(elm, ((AddressForm) pane.getChildren().get(1)).getModel());
+            assertEquals(List.of("Main", "Elm"), streets(person.getAddresses()));
+            Address pine = new Address("Pine");
+            person.getAddresses().add(pine);
+            assertEquals(3, pane.getChildren().size());
+            AddressForm pineForm = (AddressForm) pane.getChildren().get(2);
+            assertSame(pine, pineForm.getModel());
+            assertEquals("Pine", ((TextField) pineForm.lookup("#streetField")).getText());
+        });
+    }
+
+    @Test
+    void selectionIsASeparateAttributeAndTheFormsDoNotStoreIt() throws Exception {
+        onFx(() -> {
+            Address main = new Address("Main");
+            Address oak = new Address("Oak");
+            Person person = new Person("Ada");
+            person.setAddresses(new ArrayList<>(List.of(main, oak)));
+            person.setSelectedAddress(oak);
+            URL fxml = RepeatAddressComponentsTest.class.getResource("repeat-addresses.fxml");
+            assertNotNull(fxml);
+            ApplicationContext context = new ApplicationContext("de.neitzel.fx.view.component");
+            LoadedView loaded = ViewLoader.load(fxml, person, context);
+            @SuppressWarnings("unchecked")
+            ComboBox<Address> selection = (ComboBox<Address>) loaded.getRoot().lookup("#selection");
+            assertSame(oak, selection.getValue());
+            selection.setValue(null);
+            assertNull(person.getSelectedAddress());
+            selection.setValue(main);
+            assertSame(main, person.getSelectedAddress());
+            VBox pane = (VBox) loaded.getRoot().lookup("#addressPane");
+            assertEquals(2, pane.getChildren().size());
+            AddressForm first = (AddressForm) pane.getChildren().get(0);
+            AddressForm second = (AddressForm) pane.getChildren().get(1);
+            assertSame(main, first.getModel());
+            assertSame(oak, second.getModel());
+            assertEquals("Main", ((TextField) first.lookup("#streetField")).getText());
+            assertEquals("Oak", ((TextField) second.lookup("#streetField")).getText());
+        });
+    }
+
+    @Test
+    void aSecondAddressFormInTheSameDocumentIsAnotherComponent() throws Exception {
+        onFx(() -> {
+            Address home = new Address("Main");
+            Address work = new Address("Oak");
+            Person person = new Person("Ada");
+            person.setHome(home);
+            person.setWork(work);
+            URL fxml = RepeatAddressComponentsTest.class.getResource("two-address-forms.fxml");
+            assertNotNull(fxml);
+            ApplicationContext context = new ApplicationContext("de.neitzel.fx.view.component");
+            AddressForm cached = context.getComponent(AddressForm.class);
+            LoadedView loaded = ViewLoader.load(fxml, person, context);
+            AddressForm homeForm = (AddressForm) loaded.getRoot().lookup("#homeForm");
+            AddressForm workForm = (AddressForm) loaded.getRoot().lookup("#workForm");
+            assertNotNull(homeForm);
+            assertNotNull(workForm);
+            assertNotSame(homeForm, workForm);
+            assertSame(cached, context.getComponent(AddressForm.class));
+            assertSame(home, homeForm.getModel());
+            assertSame(work, workForm.getModel());
+            assertEquals("Main", ((TextField) homeForm.lookup("#streetField")).getText());
+            assertEquals("Oak", ((TextField) workForm.lookup("#streetField")).getText());
+            assertEquals("Lane", ((Label) homeForm.lookup("#streetLabel")).getText());
+            assertEquals("Lane", ((Label) workForm.lookup("#streetLabel")).getText());
+        });
+    }
+
+    private static List<String> streets(List<Address> addresses) {
+        return addresses.stream().map(Address::getStreet).toList();
+    }
+
+    private static void onFx(FxAction action) throws Exception {
+        if (Platform.isFxApplicationThread()) {
+            action.run();
+            return;
+        }
+        AtomicReference<Throwable> thrown = new AtomicReference<>();
+        CountDownLatch done = new CountDownLatch(1);
+        Platform.runLater(() -> {
+            try {
+                action.run();
+            } catch (Throwable failure) {
+                thrown.set(failure);
+            } finally {
+                done.countDown();
+            }
+        });
+        if (!done.await(10, TimeUnit.SECONDS)) {
+            fail("JavaFX thread did not finish");
+        }
+        Throwable failure = thrown.get();
+        if (failure instanceof Exception exception) {
+            throw exception;
+        }
+        if (failure instanceof Error error) {
+            throw error;
+        }
+        if (failure != null) {
+            throw new AssertionError(failure);
+        }
+    }
+
+    @FunctionalInterface
+    private interface FxAction {
+        void run() throws Exception;
+    }
+}

fx/src/test/java/de/neitzel/fx/view/fixture/Person.java

@@ -22,6 +22,8 @@ public class Person {
     private Date updated;
     private Calendar hired;
     private List<String> tags;
+    private List<Address> addresses;
+    private Address selectedAddress;
 
     /**
      * Creates a person with the given name.
@@ -256,4 +258,40 @@ public class Person {
     public void setTags(List<String> tags) {
         this.tags = tags;
     }
+
+    /**
+     * Returns the addresses. The value may be null.
+     *
+     * @return the addresses
+     */
+    public List<Address> getAddresses() {
+        return addresses;
+    }
+
+    /**
+     * Sets the addresses.
+     *
+     * @param addresses the addresses
+     */
+    public void setAddresses(List<Address> addresses) {
+        this.addresses = addresses;
+    }
+
+    /**
+     * Returns the selected address. Null means nothing is selected.
+     *
+     * @return the selected address, or {@code null}
+     */
+    public Address getSelectedAddress() {
+        return selectedAddress;
+    }
+
+    /**
+     * Sets the selected address.
+     *
+     * @param selectedAddress the selected address, or {@code null} when nothing is selected
+     */
+    public void setSelectedAddress(Address selectedAddress) {
+        this.selectedAddress = selectedAddress;
+    }
 }

fx/src/test/resources/de/neitzel/fx/view/repeat-addresses.fxml

@@ -0,0 +1,18 @@
+<?xml version="1.0" encoding="UTF-8"?>
+
+<?import javafx.scene.control.ComboBox?>
+<?import javafx.scene.layout.VBox?>
+<?import de.neitzel.fx.view.BindingList?>
+<?import de.neitzel.fx.view.DirectBinding?>
+<?import de.neitzel.fx.view.Repeat?>
+
+<VBox xmlns="http://javafx.com/javafx" xmlns:fx="http://javafx.com/fxml">
+    <fx:define>
+        <BindingList>
+            <Repeat pane="addressPane" component="de.neitzel.fx.view.component.AddressForm" collection="addresses"/>
+            <DirectBinding control="selection" property="value" path="selectedAddress" direction="both"/>
+        </BindingList>
+    </fx:define>
+    <VBox fx:id="addressPane" id="addressPane"/>
+    <ComboBox fx:id="selection" id="selection"/>
+</VBox>

fx/src/test/resources/de/neitzel/fx/view/two-address-forms.fxml

@@ -0,0 +1,17 @@
+<?xml version="1.0" encoding="UTF-8"?>
+
+<?import javafx.scene.layout.VBox?>
+<?import de.neitzel.fx.view.BindingList?>
+<?import de.neitzel.fx.view.DirectBinding?>
+<?import de.neitzel.fx.view.component.AddressForm?>
+
+<VBox xmlns="http://javafx.com/javafx" xmlns:fx="http://javafx.com/fxml">
+    <fx:define>
+        <BindingList>
+            <DirectBinding control="homeForm" property="model" path="home" direction="both"/>
+            <DirectBinding control="workForm" property="model" path="work" direction="both"/>
+        </BindingList>
+    </fx:define>
+    <AddressForm fx:id="homeForm"/>
+    <AddressForm fx:id="workForm"/>
+</VBox>

injection/src/main/java/de/neitzel/injection/ApplicationContext.java

@@ -67,11 +67,7 @@ public class ApplicationContext {
      */
     @SuppressWarnings("unchecked")
     public <T> T getComponent(Class<? extends T> type) {
-        ComponentData data = components.get(type);
-        if (data == null) {
-            throw new IllegalArgumentException("No component found for type: " + type.getName());
-        }
-
+        ComponentData data = componentData(type);
         Scope scope = data.getScope();
         Object instance = data.getInstance();
 
@@ -79,10 +75,60 @@ public class ApplicationContext {
             return (T) instance;
         }
 
+        instance = createInjected(data);
+        if (scope == Scope.SINGLETON) {
+            data.setInstance(instance);
+        }
+        return (T) instance;
+    }
+
+    /**
+     * Creates a new injected instance without replacing a cached singleton.
+     * <p>
+     * Dependencies of the new instance are the objects {@link #getComponent} returns, so a
+     * singleton dependency is still shared. The new instance itself is not stored as the
+     * singleton for {@code type}.
+     *
+     * @param <T>  the type of the component to create
+     * @param type the {@code Class} object representing the type of the component
+     * @return a new instance of the requested component type
+     * @throws IllegalArgumentException if no component is found for the specified type
+     * @throws IllegalStateException    if no suitable constructor is found for the component
+     * @throws RuntimeException         if any error occurs during instantiation
+     */
+    @SuppressWarnings("unchecked")
+    public <T> T createComponent(Class<? extends T> type) {
+        return (T) createInjected(componentData(type));
+    }
+
+    /**
+     * Returns the scanned data for a component type.
+     *
+     * @param type the component type
+     * @return the component data
+     * @throws IllegalArgumentException if no component is found for the specified type
+     */
+    private ComponentData componentData(Class<?> type) {
+        ComponentData data = components.get(type);
+        if (data == null) {
+            throw new IllegalArgumentException("No component found for type: " + type.getName());
+        }
+        return data;
+    }
+
+    /**
+     * Constructs a component and injects its dependencies.
+     * <p>
+     * The instance is not stored. {@link #getComponent} decides whether a singleton caches it.
+     *
+     * @param data the component to construct
+     * @return the new instance
+     */
+    private Object createInjected(ComponentData data) {
         try {
             Constructor<?> injectionConstructor = data.getInjectionConstructor();
             if (injectionConstructor == null) {
-                throw new IllegalStateException("No injection constructor resolved for " + type.getName());
+                throw new IllegalStateException("No injection constructor resolved for " + data.getType().getName());
             }
 
             Class<?>[] paramTypes = injectionConstructor.getParameterTypes();
@@ -91,7 +137,7 @@ public class ApplicationContext {
                 parameters[i] = getComponent(paramTypes[i]);
             }
 
-            instance = injectionConstructor.newInstance(parameters);
+            Object instance = injectionConstructor.newInstance(parameters);
 
             for (Field field : data.getInjectableFields()) {
                 field.setAccessible(true);
@@ -104,12 +150,9 @@ public class ApplicationContext {
                 setter.invoke(instance, getComponent(dependencyType));
             }
 
-            if (scope == Scope.SINGLETON) {
-                data.setInstance(instance);
-            }
-            return (T) instance;
+            return instance;
         } catch (Exception e) {
-            throw new RuntimeException("Fehler beim Erstellen der Instanz für " + type.getName(), e);
+            throw new RuntimeException("Fehler beim Erstellen der Instanz für " + data.getType().getName(), e);
         }
     }
 

injection/src/test/java/de/neitzel/injection/ApplicationContextInjectionTest.java

@@ -9,6 +9,7 @@ import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 
 import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.junit.jupiter.api.Assertions.assertNotSame;
 import static org.junit.jupiter.api.Assertions.assertSame;
 
 class ApplicationContextInjectionTest {
@@ -46,5 +47,29 @@ class ApplicationContextInjectionTest {
         assertSame(rootDependency, service.getFieldInjectedService().getRootDependency());
         assertSame(rootDependency, service.getSetterInjectedService().getRootDependency());
     }
+
+    @Test
+    void createComponentInjectsANewInstanceAndKeepsTheSingleton() {
+        MixedInjectionService singleton = context.getComponent(MixedInjectionService.class);
+        MixedInjectionService created = context.createComponent(MixedInjectionService.class);
+        RootDependency root = context.getComponent(RootDependency.class);
+        assertNotSame(singleton, created);
+        assertSame(singleton, context.getComponent(MixedInjectionService.class));
+        assertSame(root, created.getConstructorInjectedService().getRootDependency());
+        assertSame(root, created.getFieldInjectedService().getRootDependency());
+        assertSame(root, created.getSetterInjectedService().getRootDependency());
+        assertSame(singleton.getConstructorInjectedService(), created.getConstructorInjectedService());
+        assertSame(singleton.getFieldInjectedService(), created.getFieldInjectedService());
+        assertSame(singleton.getSetterInjectedService(), created.getSetterInjectedService());
+    }
+
+    @Test
+    void createComponentDoesNotBecomeTheSingleton() {
+        MixedInjectionService created = context.createComponent(MixedInjectionService.class);
+        MixedInjectionService singleton = context.getComponent(MixedInjectionService.class);
+        assertNotSame(created, singleton);
+        assertSame(singleton, context.getComponent(MixedInjectionService.class));
+        assertSame(created.getConstructorInjectedService(), singleton.getConstructorInjectedService());
+    }
 }