uebung09 small adjustments

uebung09/src/collection/SetDemo.java

@@ -0,0 +1,29 @@
+package collection;
+
+public class SetDemo {
+    public static void main(String[] args) {
+        final Set<String> set1 = SetFactory.create();
+        System.out.println("set1 = " + set1);
+
+        final Set<String> set2 = set1.add("foo");
+        System.out.println("set2 = " + set2);
+
+        final Set<String> set3 = set2.add("foo");
+        System.out.println("set3 = " + set3);
+
+        final Set<String> set4 = set3.add("bar");
+        System.out.println("set4 = " + set4);
+
+        final Set<String> set5 = SetFactory.create("foo", "baz", "foo");
+        System.out.println("set5 = " + set5);
+
+        final Set<String> set6 = set4.union(set5);
+        System.out.println("set6 = " + set6);
+
+        final Set<String> set7 = set4.intersection(set5);
+        System.out.println("set7 = " + set7);
+
+        final Set<String> set8 = set5.intersection(set4);
+        System.out.println("set8 = " + set8);
+    }
+}