I have added an example, not sure if this is really what you're asking for.

Callback implemented with lambdas
In the Callback example show how to implement the same thing with Java 8 lambdas.

callback/src/main/java/com/iluwatar/callback/LambdasApp.java
callback/src/test/java/com/iluwatar/callback/AppTest.java
diff --git a/callback/src/main/java/com/iluwatar/callback/LambdasApp.java b/callback/src/main/java/com/iluwatar/callback/LambdasApp.java
new file mode 100644
index 000000000000..19dd17eae441
--- /dev/null
+++ b/callback/src/main/java/com/iluwatar/callback/LambdasApp.java
@@ -0,0 +1,19 @@
+package com.iluwatar.callback;
+
+/**
+ *
+ * This example generates the exact same output as {@link App} however the callback has been
+ * defined as a Lambdas expression.
+ *
+ */
+public class LambdasApp {
+
+  /**
+   * Program entry point
+   */
+  public static void main(String[] args) {
+    Task task = new SimpleTask();
+    Callback c = () -> System.out.println("I'm done now.");
+    task.executeWith(c);
+  }
+}

diff --git a/callback/src/test/java/com/iluwatar/callback/AppTest.java b/callback/src/test/java/com/iluwatar/callback/AppTest.java
index 67046a175590..28d6eaa1cea1 100644
--- a/callback/src/test/java/com/iluwatar/callback/AppTest.java
+++ b/callback/src/test/java/com/iluwatar/callback/AppTest.java
@@ -36,4 +36,22 @@ public void call() {
     assertEquals("Callback called twice", new Integer(2), callingCount);
 
   }
+
+  @Test
+  public void testWithLambdasExample() {
+    Callback callback = () -> callingCount++;
+
+    Task task = new SimpleTask();
+
+    assertEquals("Initial calling count of 0", new Integer(0), callingCount);
+
+    task.executeWith(callback);
+
+    assertEquals("Callback called once", new Integer(1), callingCount);
+
+    task.executeWith(callback);
+
+    assertEquals("Callback called twice", new Integer(2), callingCount);
+
+  }
 }
