Merge commit '8b020837eaacc9ed4497f3c2461984935314bfb8' into add-delegation-pattern

* commit '8b020837eaacc9ed4497f3c2461984935314bfb8':
  Checkstyle corrections
  Checkstyle configuration to look into test classes too
  Rephrase readme title
  Corrected difficulty for Visitor #213
  Add performance tag to relevant patterns #213
  Categorize and tag all patterns #213
  Update CONTRIBUTING.MD
  Update CONTRIBUTING.MD
  add-contributing

CONTRIBUTING.MD

@@ -0,0 +1,4 @@
+This is great you have something to contribute! 
+
+Before going any further please read the [wiki](https://github.com/iluwatar/java-design-patterns/wiki)
+with conventions and rules we used for this project.

README.md

@@ -2,7 +2,7 @@
      that smart and dearly wants an empty line before a heading to be able to
      display it as such, e.g. website) -->
 
-# Design pattern samples in Java
+# Design patterns implemented in Java
 
 [![Build status](https://travis-ci.org/iluwatar/java-design-patterns.svg?branch=master)](https://travis-ci.org/iluwatar/java-design-patterns)
 [![Coverage Status](https://coveralls.io/repos/iluwatar/java-design-patterns/badge.svg?branch=master)](https://coveralls.io/r/iluwatar/java-design-patterns?branch=master)

abstract-factory/index.md

@@ -7,6 +7,7 @@ categories: Creational
 tags: 
  - Java
  - Gang Of Four
+ - Difficulty-Intermediate
 ---
 
 **Also known as:** Kit

adapter/index.md

@@ -7,6 +7,7 @@ categories: Structural
 tags:
  - Java
  - Gang Of Four
+ - Difficulty-Beginner
 ---
 
 **Also known as:** Wrapper

async-method-invocation/index.md

@@ -4,7 +4,10 @@ title: Async Method Invocation
 folder: async-method-invocation
 permalink: /patterns/async-method-invocation/
 categories: Concurrency
-tags: Java
+tags:
+ - Java
+ - Difficulty-Intermediate
+ - Functional
 ---
 
 **Intent:** Asynchronous method invocation is pattern where the calling thread

bridge/index.md

@@ -7,6 +7,7 @@ categories: Structural
 tags:
  - Java
  - Gang Of Four
+ - Difficulty-Intermediate
 ---
 
 **Also known as:** Handle/Body

builder/index.md

@@ -7,6 +7,7 @@ categories: Creational
 tags:
  - Java
  - Gang Of Four
+ - Difficulty-Intermediate
 ---
 
 **Intent:** Separate the construction of a complex object from its

business-delegate/index.md

@@ -4,7 +4,9 @@ title: Business Delegate
 folder: business-delegate
 permalink: /patterns/business-delegate/
 categories: Business Tier
-tags: Java
+tags:
+ - Java
+ - Difficulty-Intermediate
 ---
 
 **Intent:** The Business Delegate pattern adds an abstraction layer between

caching/index.md

@@ -6,6 +6,8 @@ permalink: /patterns/caching/
 categories: Other
 tags:
  - Java
+ - Difficulty-Intermediate
+ - Performance
 ---
 
 **Intent:** To avoid expensive re-acquisition of resources by not releasing

callback/index.md

@@ -4,7 +4,11 @@ title: Callback
 folder: callback
 permalink: /patterns/callback/
 categories: Other
-tags: Java
+tags:
+ - Java
+ - Difficulty-Beginner
+ - Functional
+ - Idiom
 ---
 
 **Intent:** Callback is a piece of executable code that is passed as an

chain/index.md

@@ -7,6 +7,7 @@ categories: Behavioral
 tags:
  - Java
  - Gang Of Four
+ - Difficulty-Intermediate
 ---
 
 **Intent:** Avoid coupling the sender of a request to its receiver by giving

checkstyle-suppressions.xml

@@ -0,0 +1,9 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE suppressions PUBLIC "-//Puppy Crawl//DTD Suppressions 1.1//EN"
+    "http://www.puppycrawl.com/dtds/suppressions_1_1.dtd">
+<suppressions>
+   <suppress checks="AvoidStarImport" files="[\\/]src[\\/]test[\\/]java[\\/]"/>
+   <suppress checks="[a-zA-Z0-9]*" files="[\\/]src[\\/]test[\\/]resources[\\/]"/>
+   <suppress checks="[a-zA-Z0-9]*" files="[\\/]build[\\/]generated-sources[\\/]"/>
+   <suppress checks="[a-zA-Z0-9]*" files="[\\/]src[\\/]main[\\/]resources[\\/]"/>
+</suppressions>

checkstyle.xml

@@ -158,7 +158,7 @@
             <property name="allowMissingThrowsTags" value="true"/>
             <property name="allowMissingReturnTag" value="true"/>
             <property name="minLineCount" value="2"/>
-            <property name="allowedAnnotations" value="Override, Test, Before, After, Parameters, Given, When, BeforeClass, AfterClass"/>
+            <property name="allowedAnnotations" value="Override, Test, Before, After, Parameters, Given, When, BeforeClass, AfterClass, Parameterized"/>
             <property name="allowThrowsTagsForSubclasses" value="true"/>
         </module>
         <module name="MethodName">
@@ -168,4 +168,9 @@
         </module>
         <module name="SingleLineJavadoc"/>
     </module>
+	
+    <module name="SuppressionFilter">
+        <property name="file" value="${config_loc}/checkstyle-suppressions.xml" default="checkstyle-suppressions.xml"/>
+    </module>
+	
 </module>

command/index.md

@@ -7,6 +7,7 @@ categories: Behavioral
 tags: 
  - Java
  - Gang Of Four
+ - Difficulty-Intermediate
 ---
 
 **Also known as:** Action, Transaction

composite/index.md

@@ -7,6 +7,7 @@ categories: Structural
 tags:
  - Java
  - Gang Of Four
+ - Difficulty-Intermediate
 ---
 
 **Intent:** Compose objects into tree structures to represent part-whole

dao/index.md

@@ -3,7 +3,7 @@ layout: pattern
 title: Data Access Object
 folder: dao
 permalink: /patterns/dao/
-categories: Architectural
+categories: Persistence Tier
 tags:
  - Java
  - Difficulty-Beginner

decorator/index.md

@@ -7,6 +7,7 @@ categories: Structural
 tags:
  - Java
  - Gang Of Four
+ - Difficulty-Beginner
 ---
 
 **Also known as:** Wrapper

dependency-injection/index.md

@@ -4,7 +4,9 @@ title: Dependency Injection
 folder: dependency-injection
 permalink: /patterns/dependency-injection/
 categories: Behavioral
-tags: Java
+tags:
+ - Java
+ - Difficulty-Beginner
 ---
 
 **Intent:** Dependency Injection is a software design pattern in which one or

double-checked-locking/index.md

@@ -4,7 +4,10 @@ title: Double Checked Locking
 folder: double-checked-locking
 permalink: /patterns/double-checked-locking/
 categories: Concurrency
-tags: Java
+tags:
+ - Java
+ - Difficulty-Beginner
+ - Idiom
 ---
 
 **Intent:** Reduce the overhead of acquiring a lock by first testing the

double-checked-locking/src/test/java/com/iluwatar/doublechecked/locking/InventoryTest.java

@@ -14,7 +14,10 @@ import java.util.concurrent.TimeUnit;
 import static junit.framework.Assert.assertTrue;
 import static junit.framework.TestCase.assertEquals;
 import static org.junit.Assert.assertNotNull;
-import static org.mockito.Mockito.*;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.verifyNoMoreInteractions;
 
 /**
  * Date: 12/10/15 - 9:34 PM

double-dispatch/index.md

@@ -4,7 +4,10 @@ title: Double Dispatch
 folder: double-dispatch
 permalink: /patterns/double-dispatch/
 categories: Other
-tags: Java
+tags:
+ - Java
+ - Difficulty-Intermediate
+ - Idiom
 ---
 
 **Intent:** Double Dispatch pattern is a way to create maintainable dynamic

double-dispatch/src/test/java/com/iluwatar/doubledispatch/CollisionTest.java

@@ -7,7 +7,10 @@ import java.io.PrintStream;
 import java.util.Objects;
 
 import static org.junit.Assert.assertEquals;
-import static org.mockito.Mockito.*;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.verifyNoMoreInteractions;
 
 /**
  * Date: 12/10/15 - 8:37 PM

event-aggregator/index.md

@@ -4,7 +4,9 @@ title: Event Aggregator
 folder: event-aggregator
 permalink: /patterns/event-aggregator/
 categories: Structural
-tags: Java
+tags:
+ - Java
+ - Difficulty-Beginner
 ---
 
 **Intent:** A system with lots of objects can lead to complexities when a

event-aggregator/src/test/java/com/iluwatar/event/aggregator/EventEmitterTest.java

@@ -7,7 +7,11 @@ import java.util.function.Function;
 import java.util.function.Supplier;
 
 import static org.mockito.Matchers.eq;
-import static org.mockito.Mockito.*;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.verifyZeroInteractions;
+import static org.mockito.Mockito.verifyNoMoreInteractions;
 
 /**
  * Date: 12/12/15 - 10:58 PM

event-aggregator/src/test/java/com/iluwatar/event/aggregator/KingJoffreyTest.java

@@ -6,7 +6,11 @@ import org.junit.Test;
 
 import java.io.PrintStream;
 
-import static org.mockito.Mockito.*;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.verifyZeroInteractions;
+import static org.mockito.Mockito.verifyNoMoreInteractions;
 
 /**
  * Date: 12/12/15 - 3:04 PM

event-aggregator/src/test/java/com/iluwatar/event/aggregator/KingsHandTest.java

@@ -3,7 +3,11 @@ package com.iluwatar.event.aggregator;
 import org.junit.Test;
 
 import static org.mockito.Matchers.eq;
-import static org.mockito.Mockito.*;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.verifyZeroInteractions;
+import static org.mockito.Mockito.verifyNoMoreInteractions;
 
 /**
  * Date: 12/12/15 - 10:57 AM

execute-around/index.md

@@ -4,7 +4,10 @@ title: Execute Around
 folder: execute-around
 permalink: /patterns/execute-around/
 categories: Other
-tags: Java
+tags:
+ - Java
+ - Difficulty-Beginner
+ - Idiom
 ---
 
 **Intent:** Execute Around idiom frees the user from certain actions that

facade/index.md

@@ -7,6 +7,7 @@ categories: Structural
 tags:
  - Java
  - Gang Of Four
+ - Difficulty-Beginner
 ---
 
 **Intent:** Provide a unified interface to a set of interfaces in a subsystem.

facade/src/test/java/com/iluwatar/facade/DwarvenGoldmineFacadeTest.java

@@ -7,7 +7,9 @@ import org.junit.Test;
 import java.io.PrintStream;
 
 import static org.mockito.Matchers.eq;
-import static org.mockito.Mockito.*;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.verifyNoMoreInteractions;
 import static org.mockito.internal.verification.VerificationModeFactory.times;
 
 /**

fluentinterface/index.md

@@ -7,6 +7,7 @@ categories: Other
 tags: 
  - Java
  - Difficulty-Intermediate
+ - Functional
 ---
 
 **Intent:** A fluent interface provides an easy-readable, flowing interface, that often mimics a domain specific language. Using this pattern results in code that can be read nearly as human language.

flux/index.md

@@ -4,7 +4,9 @@ title: Flux
 folder: flux
 permalink: /patterns/flux/
 categories: Presentation Tier
-tags: Java
+tags:
+ - Java
+ - Difficulty-Intermediate
 ---
 
 **Intent:** Flux eschews MVC in favor of a unidirectional data flow. When a

flux/src/test/java/com/iluwatar/flux/dispatcher/DispatcherTest.java

@@ -1,6 +1,11 @@
 package com.iluwatar.flux.dispatcher;
 
-import com.iluwatar.flux.action.*;
+import com.iluwatar.flux.action.Action;
+import com.iluwatar.flux.action.ActionType;
+import com.iluwatar.flux.action.Content;
+import com.iluwatar.flux.action.ContentAction;
+import com.iluwatar.flux.action.MenuAction;
+import com.iluwatar.flux.action.MenuItem;
 import com.iluwatar.flux.store.Store;
 import org.junit.Before;
 import org.junit.Test;
@@ -11,8 +16,13 @@ import java.lang.reflect.Field;
 import java.util.List;
 import java.util.stream.Collectors;
 
-import static org.junit.Assert.*;
-import static org.mockito.Mockito.*;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertSame;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.verifyNoMoreInteractions;
 
 /**
  * Date: 12/12/15 - 8:22 PM

flux/src/test/java/com/iluwatar/flux/store/ContentStoreTest.java

@@ -9,7 +9,11 @@ import org.junit.Test;
 
 import static org.junit.Assert.assertEquals;
 import static org.mockito.Matchers.eq;
-import static org.mockito.Mockito.*;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.verifyZeroInteractions;
+import static org.mockito.Mockito.verifyNoMoreInteractions;
 
 /**
  * Date: 12/12/15 - 10:18 PM

flux/src/test/java/com/iluwatar/flux/store/MenuStoreTest.java

@@ -9,7 +9,11 @@ import org.junit.Test;
 
 import static org.junit.Assert.assertEquals;
 import static org.mockito.Matchers.eq;
-import static org.mockito.Mockito.*;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.verifyZeroInteractions;
+import static org.mockito.Mockito.verifyNoMoreInteractions;
 
 /**
  * Date: 12/12/15 - 10:18 PM

flux/src/test/java/com/iluwatar/flux/view/ContentViewTest.java

@@ -4,7 +4,11 @@ import com.iluwatar.flux.action.Content;
 import com.iluwatar.flux.store.ContentStore;
 import org.junit.Test;
 
-import static org.mockito.Mockito.*;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+import static org.mockito.Mockito.verifyNoMoreInteractions;
 
 /**
  * Date: 12/12/15 - 10:31 PM

flux/src/test/java/com/iluwatar/flux/view/MenuViewTest.java

@@ -8,7 +8,11 @@ import com.iluwatar.flux.store.Store;
 import org.junit.Test;
 
 import static org.mockito.Matchers.any;
-import static org.mockito.Mockito.*;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.verifyNoMoreInteractions;
+import static org.mockito.Mockito.when;
 
 /**
  * Date: 12/12/15 - 10:31 PM

flyweight/index.md

@@ -7,6 +7,8 @@ categories: Structural
 tags: 
  - Java
  - Gang Of Four
+ - Difficulty-Intermediate
+ - Performance
 ---
 
 **Intent:** Use sharing to support large numbers of fine-grained objects

front-controller/index.md

@@ -4,7 +4,9 @@ title: Front Controller
 folder: front-controller
 permalink: /patterns/front-controller/
 categories: Presentation Tier
-tags: Java
+tags:
+ - Java
+ - Difficulty-Intermediate
 ---
 
 **Intent:** Introduce a common handler for all requests for a web site. This

half-sync-half-async/index.md

@@ -4,7 +4,9 @@ title: Half-Sync/Half-Async
 folder: half-sync-half-async
 permalink: /patterns/half-sync-half-async/
 categories: Concurrency
-tags: Java
+tags:
+ - Java
+ - Difficulty-Intermediate
 ---
 
 **Intent:** The Half-Sync/Half-Async pattern decouples synchronous I/O from

intercepting-filter/index.md

@@ -4,7 +4,9 @@ title: Intercepting Filter
 folder: intercepting-filter
 permalink: /patterns/intercepting-filter/
 categories: Behavioral
-tags: Java
+tags:
+ - Java
+ - Difficulty-Intermediate
 ---
 
 **Intent:** Provide pluggable filters to conduct necessary pre-processing and

intercepting-filter/src/test/java/com/iluwatar/intercepting/filter/FilterManagerTest.java

@@ -4,7 +4,11 @@ import org.junit.Test;
 
 import static org.junit.Assert.assertEquals;
 import static org.mockito.Matchers.any;
-import static org.mockito.Mockito.*;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.verifyZeroInteractions;
+import static org.mockito.Mockito.when;
 
 /**
  * Date: 12/13/15 - 3:01 PM

interpreter/index.md

@@ -7,6 +7,7 @@ categories: Behavioral
 tags: 
  - Java
  - Gang Of Four
+ - Difficulty-Intermediate
 ---
 
 **Intent:** Given a language, define a representation for its grammar along

layers/index.md

@@ -4,7 +4,10 @@ title: Layers
 folder: layers
 permalink: /patterns/layers/
 categories: Architectural
-tags: Java
+tags:
+ - Java
+ - Difficulty-Intermediate
+ - Spring
 ---
 
 **Intent:** Layers is an architectural style where software responsibilities are

layers/src/test/java/com/iluwatar/layers/CakeTest.java

@@ -88,8 +88,8 @@ public class CakeTest {
     cake.setTopping(topping);
     cake.addLayer(layer);
 
-    final String expected = "id=1234 topping=id=2345 name=topping calories=20 " +
-            "layers=[id=3456 name=layer calories=100]";
+    final String expected = "id=1234 topping=id=2345 name=topping calories=20 " 
+            + "layers=[id=3456 name=layer calories=100]";
     assertEquals(expected, cake.toString());
 
   }

lazy-loading/index.md

@@ -4,7 +4,11 @@ title: Lazy Loading
 folder: lazy-loading
 permalink: /patterns/lazy-loading/
 categories: Other
-tags: Java
+tags:
+ - Java
+ - Difficulty-Beginner
+ - Idiom
+ - Performance
 ---
 
 **Intent:** Lazy loading is a design pattern commonly used to defer

mediator/src/test/java/com/iluwatar/mediator/PartyMemberTest.java

@@ -12,7 +12,10 @@ import java.util.Collection;
 import java.util.function.Supplier;
 
 import static org.junit.Assert.assertEquals;
-import static org.mockito.Mockito.*;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.verifyNoMoreInteractions;
+import static org.mockito.Mockito.verifyZeroInteractions;
 
 /**
  * Date: 12/19/15 - 10:13 PM

memento/index.md

@@ -7,6 +7,7 @@ categories: Behavioral
 tags:
  - Java
  - Gang Of Four
+ - Difficulty-Intermediate
 ---
 
 **Also known as:** Token

message-channel/index.md

@@ -7,6 +7,7 @@ categories: Integration
 tags: 
  - Java
  - EIP
+ - Camel
 ---
 
 **Intent:** When two applications communicate using a messaging system they do it by using logical addresses

model-view-controller/index.md

@@ -4,7 +4,9 @@ title: Model-View-Controller
 folder: model-view-controller
 permalink: /patterns/model-view-controller/
 categories: Presentation Tier
-tags: Java
+tags:
+ - Java
+ - Difficulty-Intermediate
 ---
 
 **Intent:** Separate the user interface into three interconnected components:

model-view-presenter/index.md

@@ -4,7 +4,9 @@ title: Model-View-Presenter
 folder: model-view-presenter
 permalink: /patterns/model-view-presenter/
 categories: Presentation Tier
-tags: Java
+tags:
+ - Java
+ - Difficulty-Intermediate
 ---
 
 **Intent:** Apply a "Separation of Concerns" principle in a way that allows

monostate/index.md

@@ -4,7 +4,9 @@ title: MonoState
 folder: monostate
 permalink: /patterns/monostate/
 categories: Creational
-tags: Java
+tags:
+ - Java
+ - Difficulty-Beginner
 ---
 
 **Intent:** Enforces a behaviour like sharing the same state amongst all instances.

multiton/index.md

@@ -4,7 +4,9 @@ title: Multiton
 folder: multiton
 permalink: /patterns/multiton/
 categories: Creational
-tags: Java
+tags:
+ - Java
+ - Difficulty-Beginner
 ---
 
 **Intent:** Ensure a class only has limited number of instances, and provide a

naked-objects/index.md

@@ -4,7 +4,9 @@ title: Naked Objects
 folder: naked-objects
 permalink: /patterns/naked-objects/
 categories: Architectural
-tags: Java
+tags:
+ - Java
+ - Difficulty-Expert
 ---
 
 **Intent:** The Naked Objects architectural pattern is well suited for rapid

null-object/index.md

@@ -4,7 +4,9 @@ title: Null Object
 folder: null-object
 permalink: /patterns/null-object/
 categories: Behavioral
-tags: Java
+tags:
+ - Java
+ - Difficulty-Beginner
 ---
 
 **Intent:** In most object-oriented languages, such as Java or C#, references

object-pool/index.md

@@ -4,7 +4,10 @@ title: Object Pool
 folder: object-pool
 permalink: /patterns/object-pool/
 categories: Creational
-tags: Java
+tags:
+ - Java
+ - Difficulty-Beginner
+ - Performance
 ---
 
 **Intent:** When objects are expensive to create and they are needed only for

poison-pill/index.md

@@ -4,7 +4,9 @@ title: Poison Pill
 folder: poison-pill
 permalink: /patterns/poison-pill/
 categories: Other
-tags: Java
+tags:
+ - Java
+ - Difficulty-Intermediate
 ---
 
 **Intent:** Poison Pill is known predefined data item that allows to provide

pom.xml

@@ -258,6 +258,7 @@
 							<encoding>UTF-8</encoding>
 							<consoleOutput>true</consoleOutput>
 							<failsOnError>true</failsOnError>
+							<includeTestSourceDirectory>true</includeTestSourceDirectory>
 						</configuration>
 					</execution>
 				</executions>

private-class-data/index.md

@@ -4,7 +4,10 @@ title: Private Class Data
 folder: private-class-data
 permalink: /patterns/private-class-data/
 categories: Other
-tags: Java
+tags:
+ - Java
+ - Difficulty-Beginner
+ - Idiom
 ---
 
 **Intent:** Private Class Data design pattern seeks to reduce exposure of

producer-consumer/index.md

@@ -3,15 +3,16 @@ layout: pattern
 title: Producer Consumer
 folder: producer-consumer
 permalink: /patterns/producer-consumer/
-categories: Other
-tags: Java
+categories: Concurrency
+tags:
+ - Java
+ - Difficulty-Intermediate
+ - I/O
 ---
 
-**Intent:** Producer Consumer Design pattern is a classic concurrency or threading pattern which reduces
+**Intent:** Producer Consumer Design pattern is a classic concurrency pattern which reduces
  coupling between Producer and Consumer by separating Identification of work with Execution of
- Work..
-
-
+ Work.
 
 ![alt text](./etc/producer-consumer.png "Producer Consumer")
 
@@ -19,4 +20,3 @@ tags: Java
 
 * decouple system by separate work in two process produce and consume.
 * addresses the issue of different timing require to produce work or consuming work
-

property/index.md

@@ -4,7 +4,9 @@ title: Property
 folder: property
 permalink: /patterns/property/
 categories: Creational
-tags: Java
+tags:
+ - Java
+ - Difficulty-Beginner
 ---
 
 **Intent:** Create hierarchy of objects and new objects using already existing

prototype/index.md

@@ -7,6 +7,7 @@ categories: Creational
 tags: 
  - Java
  - Gang Of Four
+ - Difficulty-Beginner
 ---
 
 **Intent:** Specify the kinds of objects to create using a prototypical

proxy/index.md

@@ -7,7 +7,7 @@ categories: Structural
 tags:
  - Java
  - Gang Of Four
- - Difficulty-Intermediate
+ - Difficulty-Beginner
 ---
 
 **Also known as:** Surrogate

publish-subscribe/index.md

@@ -7,6 +7,7 @@ categories: Integration
 tags: 
  - Java
  - EIP
+ - Camel
 ---
 
 **Intent:** Broadcast messages from sender to all the interested receivers.

reactor/index.md

@@ -3,10 +3,11 @@ layout: pattern
 title: Reactor
 folder: reactor
 permalink: /patterns/reactor/
-categories: Architectural
+categories: Concurrency
 tags: 
  - Java
  - Difficulty-Expert
+ - I/O
 ---
 
 **Intent:** The Reactor design pattern handles service requests that are delivered concurrently to an application by one or more clients. The application can register specific handlers for processing which are called by reactor on specific events. Dispatching of event handlers is performed by an initiation dispatcher, which manages the registered event handlers. Demultiplexing of service requests is performed by a synchronous event demultiplexer.

repository/index.md

@@ -3,8 +3,11 @@ layout: pattern
 title: Repository
 folder: repository
 permalink: /patterns/repository/
-categories: Architectural
-tags: Java
+categories: Persistence Tier
+tags:
+ - Java
+ - Difficulty-Intermediate
+ - Spring
 ---
 
 **Intent:** Repository layer is added between the domain and data mapping

resource-acquisition-is-initialization/index.md

@@ -4,7 +4,10 @@ title: Resource Acquisition Is Initialization
 folder: resource-acquisition-is-initialization
 permalink: /patterns/resource-acquisition-is-initialization/
 categories: Other
-tags: Java
+tags:
+ - Java
+ - Difficulty-Beginner
+ - Idiom
 ---
 
 **Intent:** Resource Acquisition Is Initialization pattern can be used to implement exception safe resource management.

servant/index.md

@@ -4,7 +4,9 @@ title: Servant
 folder: servant
 permalink: /patterns/servant/
 categories: Structural
-tags: Java
+tags:
+ - Java
+ - Difficulty-Beginner
 ---
 
 **Intent:** Servant is used for providing some behavior to a group of classes.

service-layer/index.md

@@ -4,7 +4,9 @@ title: Service Layer
 folder: service-layer
 permalink: /patterns/service-layer/
 categories: Architectural
-tags: Java
+tags:
+ - Java
+ - Difficulty-Intermediate
 ---
 
 **Intent:** Service Layer is an abstraction over domain logic. Typically

service-locator/index.md

@@ -4,7 +4,10 @@ title: Service Locator
 folder: service-locator
 permalink: /patterns/service-locator/
 categories: Structural
-tags: Java
+tags:
+ - Java
+ - Difficulty-Beginner
+ - Performance
 ---
 
 **Intent:** Encapsulate the processes involved in obtaining a service with a

specification/index.md

@@ -4,7 +4,9 @@ title: Specification
 folder: specification
 permalink: /patterns/specification/
 categories: Behavioral
-tags: Java
+tags:
+ - Java
+ - Difficulty-Beginner
 ---
 
 **Intent:** Specification pattern separates the statement of how to match a

step-builder/index.md

@@ -4,7 +4,9 @@ title: Step Builder
 folder: step-builder
 permalink: /patterns/step-builder/
 categories: Creational
-tags: Java
+tags:
+ - Java
+ - Difficulty-Intermediate
 ---
 
 **Intent:** An extension of the Builder pattern that fully guides the user through the creation of the object with no chances of confusion.

thread-pool/index.md

@@ -4,7 +4,10 @@ title: Thread Pool
 folder: thread-pool
 permalink: /patterns/thread-pool/
 categories: Concurrency
-tags: Java
+tags:
+ - Java
+ - Difficulty-Intermediate
+ - Performance
 ---
 
 **Intent:** It is often the case that tasks to be executed are short-lived and

tolerant-reader/index.md

@@ -4,7 +4,9 @@ title: Tolerant Reader
 folder: tolerant-reader
 permalink: /patterns/tolerant-reader/
 categories: Integration
-tags: Java
+tags:
+ - Java
+ - Difficulty-Beginner
 ---
 
 **Intent:** Tolerant Reader is an integration pattern that helps creating

twin/index.md

@@ -4,14 +4,14 @@ title: Twin
 folder: twin
 permalink: /patterns/twin/
 categories: Creational
-tags: Java
+tags:
+ - Java
+ - Difficulty-Intermediate
 ---
 
 **Intent:**  Twin pattern is a design pattern which provides a standard solution to simulate multiple
 inheritance in java
 
-
-
 ![alt text](./etc/twin.png "Twin")
 
 **Applicability:** Use the Twin idiom when

visitor/index.md

@@ -6,7 +6,7 @@ permalink: /patterns/visitor/
 categories: Behavioral
 tags:
  - Java
- - Difficulty-Expert
+ - Difficulty-Intermediate
  - Gang Of Four
 ---