Started to implement a 'ListenerHandleDemo'. It currently covers the construction of handles.

Author: nicolaiparlog

src/demo/java/org/codefx/libfx/listener/handle/ListenerHandleDemo.java

@@ -0,0 +1,112 @@
+package org.codefx.libfx.listener.handle;
+
+import javafx.beans.Observable;
+import javafx.beans.property.Property;
+import javafx.beans.property.SimpleStringProperty;
+import javafx.beans.value.ChangeListener;
+
+/**
+ * Demonstrates how to create and use {@link ListenerHandle}s.
+ */
+@SuppressWarnings("static-method")
+public class ListenerHandleDemo {
+
+	// #region CONSTRUCTION & MAIN
+
+	/**
+	 * Creates a new demo.
+	 */
+	private ListenerHandleDemo() {
+		// nothing to do
+	}
+
+	/**
+	 * Runs this demo.
+	 *
+	 * @param args
+	 *            command line arguments (will not be used)
+	 */
+	public static void main(String[] args) {
+		ListenerHandleDemo demo = new ListenerHandleDemo();
+
+		demo.createCommonListenerHandle();
+		demo.createCustomListenerHandle();
+	}
+
+	// #end CONSTRUCTION & MAIN
+
+	// #region DEMOS
+
+	// construction
+
+	/**
+	 * Demonstrates how to simply create a handle for a given observable and listener.
+	 */
+	private void createCommonListenerHandle() {
+		Property<String> property = new SimpleStringProperty();
+		ChangeListener<String> listener = (obs, oldValue, newValue) -> { /* do nothing for this demo */};
+
+		// create the handle; this one is initially attached, i.e. the listener is added to the property
+		ListenerHandle handle = ListenerHandles.create(property, listener);
+		// the handle can be used to easily detach and reattach the listener
+		handle.detach();
+		handle.attach();
+
+		// create a detached handle where the listener was not yet added to the property
+		handle = ListenerHandles.createDetached(property, listener);
+		// this one needs to be attached before the listener is executed on changes
+		handle.attach();
+	}
+
+	/**
+	 * Demonstrates how a listener handle can be created for custom observable implementations with
+	 * {@link ListenerHandleBuilder}.
+	 */
+	private void createCustomListenerHandle() {
+		MyCustomObservable customObservable = new MyCustomObservable();
+		MyCustomListener customListener = new MyCustomListener();
+
+		// use 'ListenerHandles' to get a 'ListenerHandleBuilder' which can be used to create a handle for this
+		// observable and listener
+		ListenerHandle handleForCustomClasses = ListenerHandles
+				.createFor(customObservable, customListener)
+				.onAttach((observable, listener) -> observable.addListener(listener))
+				.onDetach((observable, listener) -> observable.removeListener(listener))
+				.build();
+		handleForCustomClasses.attach();
+	}
+
+	// #end DEMOS
+
+	// #region NESTED CLASSES
+
+	/**
+	 * Represents a custom observable instance. Note that it is not necessary to implement {@link Observable} (or any
+	 * other interface) in order to use this class with the {@link ListenerHandleBuilder}.
+	 */
+	private static class MyCustomObservable {
+
+		@SuppressWarnings({ "javadoc", "unused" })
+		public void addListener(MyCustomListener listener) {
+			// do nothing - just for demo
+		}
+
+		@SuppressWarnings({ "javadoc", "unused" })
+		public void removeListener(MyCustomListener listener) {
+			// do nothing - just for demo
+		}
+
+	}
+
+	/**
+	 * Represents a listener for a custom observable instance. Note that it is not necessary to implement
+	 * {@link ChangeListener} (or any other interface) in order to use this class with the {@link ListenerHandleBuilder}
+	 * .
+	 */
+	private static class MyCustomListener {
+		// has no members - just for demo
+	}
+
+	// #end NESTED CLASSES
+
+}