added adapter example

src/learn/simple_adapter/Main.java

@@ -0,0 +1,9 @@
+package learn.simple_adapter;
+
+public class Main {
+    public static void main(String[] args) {
+        Adaptee adaptee = new Adaptee();
+        Target adapter = new Adapter(adaptee);
+        adapter.request();
+    }
+}