Create tutorial_53.java

simply-coded · web-flow · commit 9178d4aaf58e · 2017-06-09T19:35:03.000-05:00
diff --git a/code/tutorial_53.java b/code/tutorial_53.java
@@ -0,0 +1,61 @@
+@FunctionalInterface
+interface Filter {
+    boolean test(String n);
+}
+@FunctionalInterface
+interface Adder {
+    int run(int n1, int n2);
+}
+//
+//
+public class Driver {
+
+    public static void main(String[] args) {
+        
+        // main example
+        String[] friends = { "jim", "kate", "bill", "mark", "devin", "alice", "melvin", "jeremy", "bob" };
+
+        Messenger group = new Messenger(friends);
+        String mess = "RSVP to my party.";
+
+        group.send(mess, n -> n.charAt(0) == 'm');
+        group.send(mess, n -> n.length() == 4);
+        group.send(mess, n -> true);
+
+        // create a lambda
+        Adder add = (a, b) -> a + b;
+
+        // execute a lambda
+        int result1 = add.run(56, 79);
+
+        // execute a lambda immediately
+        int result2 = ( (Adder) (a, b) -> a + b ).run(13,28);
+
+        // multiple statements in a lambda
+        int result3 = ((Adder)(a, b) -> {
+            System.out.print("The result = ");
+            return a + b;
+        }).run(5, 16);
+        System.out.println(result3);
+    }
+
+}
+//
+//
+class Messenger {
+
+    protected String[] contactList;
+
+    public Messenger(String[] names) {
+        contactList = names;
+    }
+
+    public void send(String message, Filter filter) {
+        for (String name: contactList) {
+            if (filter.test(name)) {
+                System.out.println(name + ": " + message);
+            }
+        }
+    }
+
+}
