new tasks

Task/Delegates/Java/delegates.java

@@ -0,0 +1,43 @@
+interface Thingable {
+    String thing();
+}
+
+class Delegator {
+    public Thingable delegate;
+
+    public String operation() {
+        if (delegate == null)
+            return "default implementation";
+        else
+            return delegate.thing();
+    }
+}
+
+class Delegate implements Thingable {
+    public String thing() {
+        return "delegate implementation";
+    }
+}
+
+// Example usage
+// Memory management ignored for simplification
+public class DelegateExample {
+    public static void main(String[] args) {
+        // Without a delegate:
+        Delegator a = new Delegator();
+        assert a.operation().equals("default implementation");
+
+        // With a delegate:
+        Delegate d = new Delegate();
+        a.delegate = d;
+        assert a.operation().equals("delegate implementation");
+
+        // Same as the above, but with an anonymous class:
+        a.delegate = new Thingable() {
+                public String thing() {
+                    return "anonymous delegate implementation";
+                }
+            };
+        assert a.operation().equals("anonymous delegate implementation");
+    }
+}