Create a super-small demo for equality transformation

Author: nicolaiparlog

src/demo/java/org/codefx/libfx/collection/transform/EqualityTransformingSetDemo.java

@@ -0,0 +1,55 @@
+package org.codefx.libfx.collection.transform;
+
+import java.util.Set;
+
+/**
+ * Demonstrates how to use the {@link EqualityTransformingSet}.
+ * <p>
+ * The demonstrated example is based on the situation that we want a set of strings which uses only their length for
+ * equality comparison.
+ */
+public class EqualityTransformingSetDemo {
+
+	/**
+	 * A set of strings which uses the length for equality.
+	 */
+	private final Set<String> lengthSet;
+
+	/**
+	 * Creates a new demo.
+	 */
+	public EqualityTransformingSetDemo() {
+		lengthSet = EqualityTransformingCollectionBuilder
+				.forType(String.class)
+				.withEquals((a, b) -> a.length() == b.length())
+				.withHash(String::length)
+				.buildSet();
+	}
+
+	/**
+	 * Runs this demo.
+	 *
+	 * @param args
+	 *            command line arguments (will not be used)
+	 */
+	public static void main(String[] args) {
+		EqualityTransformingSetDemo demo = new EqualityTransformingSetDemo();
+
+		demo.addSomeElements();
+	}
+
+	private void addSomeElements() {
+		lengthSet.add("a");
+		lengthSet.add("b");
+		print(lengthSet.toString());
+	}
+
+	private static void print() {
+		System.out.println();
+	}
+
+	private static void print(String text) {
+		System.out.println(text);
+	}
+
+}