diff --git a/adapter/src/main/java/com/iluwatar/App.java b/adapter/src/main/java/com/iluwatar/App.java
index 54bd3c17fff2..b96a6be8c320 100644
--- a/adapter/src/main/java/com/iluwatar/App.java
+++ b/adapter/src/main/java/com/iluwatar/App.java
@@ -10,6 +10,13 @@
  * The Adapter (GnomeEngineer) converts the interface of the target class
  * (GoblinGlider) into a suitable one expected by the client
  * (GnomeEngineeringManager).
+ *
+ * 适配器模式是为了实现两个不兼容的接口的兼容的模式。因此，当使用适配器的时候或许就是接口设计不合理的原因。。
+ * 这个原因有很多，比如双方在这几功能模块的时候互相之间并没有合作，或者自己的设计思想没有照顾到以后的变化。也或者是
+ * 双方就不属于统一体系架构下的东西。
+ * 另外适配器也可以实现功能的多样化，在设计模块的时候无需过度考虑兼容性问题，使用适配器可以很好的解决设计与应用的问题。
+ * 一个适配器同时拥有一方的接口，同时也是另一方接口的实现类。
+ *
  * 
  */
 public class App {
diff --git a/builder/src/main/java/com/iluwatar/App.java b/builder/src/main/java/com/iluwatar/App.java
index 59348de6e84d..b0140ccf68d3 100644
--- a/builder/src/main/java/com/iluwatar/App.java
+++ b/builder/src/main/java/com/iluwatar/App.java
@@ -13,6 +13,13 @@
  * constructor. After that additional configuration for the Hero object can be
  * done using the fluent HeroBuilder interface. When configuration is ready the
  * build method is called to receive the final Hero object.
+ *
+ * 构建者模式是一种对象初始化过程复杂的封装。如果一种对象的初始化参数过多，参数的变化也比较多可以考虑构建者模式。
+ * 很典型的应用场景就是如果你的类有很多个参数，或者你的类的构造方法很多，可以使用它。
+ * 这个设计模式的结构比较简单，静态内部类作为构建者类，然后被构建者的构造方法只需要一个构建者参数。
+ * 然后初始化的过程从构建者对象中获取。因此，被构建者的构造方法无需公开。
+ * 构建者类是被构建者对外开放的接口。因此，这个接口的设计尽量的人性化，简单易懂。最后使用一个build来构造出目标对象。
+ *
  * 
  */
 public class App {
diff --git a/builder/src/main/java/com/iluwatar/Hero.java b/builder/src/main/java/com/iluwatar/Hero.java
index 8fb00667b612..6cc3233d305d 100644
--- a/builder/src/main/java/com/iluwatar/Hero.java
+++ b/builder/src/main/java/com/iluwatar/Hero.java
@@ -1,129 +1,125 @@
 package com.iluwatar;
 
 /**
- * 
  * The class with many parameters.
- * 
  */
 public class Hero {
 
-	private final Profession profession;
-	private final String name;
-	private final HairType hairType;
-	private final HairColor hairColor;
-	private final Armor armor;
-	private final Weapon weapon;
-
-	public Profession getProfession() {
-		return profession;
-	}
-
-	public String getName() {
-		return name;
-	}
-
-	public HairType getHairType() {
-		return hairType;
-	}
-
-	public HairColor getHairColor() {
-		return hairColor;
-	}
-
-	public Armor getArmor() {
-		return armor;
-	}
-
-	public Weapon getWeapon() {
-		return weapon;
-	}
-
-	@Override
-	public String toString() {
-
-		StringBuilder sb = new StringBuilder();
-		sb.append("This is a ");
-		sb.append(profession);
-		sb.append(" named ");
-		sb.append(name);
-		if (hairColor != null || hairType != null) {
-			sb.append(" with ");
-			if (hairColor != null) {
-				sb.append(hairColor);
-				sb.append(" ");
-			}
-			if (hairType != null) {
-				sb.append(hairType);
-				sb.append(" ");
-			}
-			sb.append(hairType != HairType.BALD ? "hair" : "head");
-		}
-		if (armor != null) {
-			sb.append(" wearing ");
-			sb.append(armor);
-		}
-		if (weapon != null) {
-			sb.append(" and wielding a ");
-			sb.append(weapon);
-		}
-		sb.append(".");
-		return sb.toString();
-	}
-
-	private Hero(HeroBuilder builder) {
-		this.profession = builder.profession;
-		this.name = builder.name;
-		this.hairColor = builder.hairColor;
-		this.hairType = builder.hairType;
-		this.weapon = builder.weapon;
-		this.armor = builder.armor;
-	}
-
-	/**
-	 * 
-	 * The builder class.
-	 * 
-	 */
-	public static class HeroBuilder {
-
-		private final Profession profession;
-		private final String name;
-		private HairType hairType;
-		private HairColor hairColor;
-		private Armor armor;
-		private Weapon weapon;
-
-		public HeroBuilder(Profession profession, String name) {
-			if (profession == null || name == null) {
-				throw new IllegalArgumentException(
-						"profession and name can not be null");
-			}
-			this.profession = profession;
-			this.name = name;
-		}
-
-		public HeroBuilder withHairType(HairType hairType) {
-			this.hairType = hairType;
-			return this;
-		}
-
-		public HeroBuilder withHairColor(HairColor hairColor) {
-			this.hairColor = hairColor;
-			return this;
-		}
-
-		public HeroBuilder withArmor(Armor armor) {
-			this.armor = armor;
-			return this;
-		}
-
-		public HeroBuilder withWeapon(Weapon weapon) {
-			this.weapon = weapon;
-			return this;
-		}
-
-		public Hero build() {
-			return new Hero(this);
-		}
-	}
+    private final Profession profession;
+    private final String name;
+    private final HairType hairType;
+    private final HairColor hairColor;
+    private final Armor armor;
+    private final Weapon weapon;
+
+    public Profession getProfession() {
+        return profession;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public HairType getHairType() {
+        return hairType;
+    }
+
+    public HairColor getHairColor() {
+        return hairColor;
+    }
+
+    public Armor getArmor() {
+        return armor;
+    }
+
+    public Weapon getWeapon() {
+        return weapon;
+    }
+
+    @Override
+    public String toString() {
+
+        StringBuilder sb = new StringBuilder();
+        sb.append("This is a ");
+        sb.append(profession);
+        sb.append(" named ");
+        sb.append(name);
+        if (hairColor != null || hairType != null) {
+            sb.append(" with ");
+            if (hairColor != null) {
+                sb.append(hairColor);
+                sb.append(" ");
+            }
+            if (hairType != null) {
+                sb.append(hairType);
+                sb.append(" ");
+            }
+            sb.append(hairType != HairType.BALD ? "hair" : "head");
+        }
+        if (armor != null) {
+            sb.append(" wearing ");
+            sb.append(armor);
+        }
+        if (weapon != null) {
+            sb.append(" and wielding a ");
+            sb.append(weapon);
+        }
+        sb.append(".");
+        return sb.toString();
+    }
+
+    private Hero(HeroBuilder builder) {
+        this.profession = builder.profession;
+        this.name = builder.name;
+        this.hairColor = builder.hairColor;
+        this.hairType = builder.hairType;
+        this.weapon = builder.weapon;
+        this.armor = builder.armor;
+    }
+
+    /**
+     * The builder class.
+     */
+    public static class HeroBuilder {
+
+        private final Profession profession;
+        private final String name;
+        private HairType hairType;
+        private HairColor hairColor;
+        private Armor armor;
+        private Weapon weapon;
+
+        public HeroBuilder(Profession profession, String name) {
+            if (profession == null || name == null) {
+                throw new IllegalArgumentException(
+                        "profession and name can not be null");
+            }
+            this.profession = profession;
+            this.name = name;
+        }
+
+        public HeroBuilder withHairType(HairType hairType) {
+            this.hairType = hairType;
+            return this;
+        }
+
+        public HeroBuilder withHairColor(HairColor hairColor) {
+            this.hairColor = hairColor;
+            return this;
+        }
+
+        public HeroBuilder withArmor(Armor armor) {
+            this.armor = armor;
+            return this;
+        }
+
+        public HeroBuilder withWeapon(Weapon weapon) {
+            this.weapon = weapon;
+            return this;
+        }
+
+        public Hero build() {
+            return new Hero(this);
+        }
+    }
 }
diff --git a/callback/src/main/java/com/iluwatar/App.java b/callback/src/main/java/com/iluwatar/App.java
index 2d79d8edf6c7..5bec308194bf 100644
--- a/callback/src/main/java/com/iluwatar/App.java
+++ b/callback/src/main/java/com/iluwatar/App.java
@@ -3,17 +3,18 @@
 /**
  * Callback pattern is more native for functional languages where function is treated as first-class citizen.
  * Prior to Java8 can be simulated using simple (alike command) interfaces.
+ * 回调设计模式是一种过程式程序语言的设计。
+ * 任务执行完成之后，
  */
 public class App {
 
-	public static void main(String[] args) {
-		Task task = new SimpleTask();
-		Callback callback = new Callback() {
-			@Override
-			public void call() {
-				System.out.println("I'm done now.");
-			}
-		};
-		task.executeWith(callback);
-	}
+    public static void main(String[] args) {
+        Task task = new SimpleTask();
+        task.executeWith(new Callback() {
+            @Override
+            public void call() {
+                System.out.println("I'm done now.");
+            }
+        });
+    }
 }
diff --git a/chain/src/main/java/com/iluwatar/App.java b/chain/src/main/java/com/iluwatar/App.java
index 480ddc169f0b..3cacb504168d 100644
--- a/chain/src/main/java/com/iluwatar/App.java
+++ b/chain/src/main/java/com/iluwatar/App.java
@@ -1,22 +1,49 @@
 package com.iluwatar;
 
 /**
- * 
  * Chain of Responsibility organizes request handlers (RequestHandler) into a
  * chain where each handler has a chance to act on the request on its turn. In
  * this example the king (OrcKing) makes requests and the military orcs
  * (OrcCommander, OrcOfficer, OrcSoldier) form the handler chain.
- * 
+ * 职责链模式重点在于职责，其组织结构是链式结构，使用者构建职责链条。
+ * 原始的模式其实一长条的if else判断或者是switch case语句。本模式其实是将if else繁杂的判断分离出来形成单个的判断。
+ * 模式的构成主要是一个抽象的职责类。这个类包含一个下级链条的引用及本级处理请求的方法。在这个方法里判断
+ * 是否自己处理，或者留给下一级来处理。
+ * 客户端使用的时候来创建链条结构。
+ * <p>
+ * 可以用做一个过滤器，不过话说一长条的if else本来就是一个过滤器。
  */
 public class App {
 
-	public static void main(String[] args) {
+    public static void main(String[] args) {
 
-		OrcKing king = new OrcKing();
-		king.makeRequest(new Request(RequestType.DEFEND_CASTLE, "defend castle"));
-		king.makeRequest(new Request(RequestType.TORTURE_PRISONER,
-				"torture prisoner"));
-		king.makeRequest(new Request(RequestType.COLLECT_TAX, "collect tax"));
+        OrcKing king = new OrcKing();
+        king.makeRequest(RequestType.DEFEND_CASTLE);
+        king.makeRequest(RequestType.TORTURE_PRISONER);
+        king.makeRequest(RequestType.COLLECT_TAX);
 
-	}
+
+    }
+
+    public static void switchPattern(RequestType type) {
+        switch (type) {
+            case DEFEND_CASTLE:
+                //直接处理不交给下一级
+                break;
+            case TORTURE_PRISONER:
+                break;
+            case COLLECT_TAX:
+                break;
+        }
+    }
+
+    public static void simplePattern(RequestType type) {
+        if (type == RequestType.DEFEND_CASTLE) {
+
+        } else if (type == RequestType.TORTURE_PRISONER) {
+
+        } else if (type == RequestType.COLLECT_TAX) {
+
+        }
+    }
 }
diff --git a/chain/src/main/java/com/iluwatar/OrcCommander.java b/chain/src/main/java/com/iluwatar/OrcCommander.java
index 1f3b6169b95e..a252878a04be 100644
--- a/chain/src/main/java/com/iluwatar/OrcCommander.java
+++ b/chain/src/main/java/com/iluwatar/OrcCommander.java
@@ -2,21 +2,23 @@
 
 public class OrcCommander extends RequestHandler {
 
-	public OrcCommander(RequestHandler handler) {
-		super(handler);
-	}
+    public OrcCommander(RequestHandler handler) {
+        super(handler);
+    }
 
-	@Override
-	public void handleRequest(Request req) {
-		if (req.getRequestType().equals(RequestType.DEFEND_CASTLE)) {
-			printHandling(req);
-		} else {
-			super.handleRequest(req);
-		}
-	}
+    @Override
+    public void handleRequest(Request req) {
+        //在这里处理上一级下发下来的请求，如果符合自己的责任则处理
+        if (req.getRequestType().equals(RequestType.DEFEND_CASTLE)) {
+            printHandling(req);
+        } else {
+            //如果不符合，则留给下一级处理
+            super.handleRequest(req);
+        }
+    }
 
-	@Override
-	public String toString() {
-		return "Orc commander";
-	}
+    @Override
+    public String toString() {
+        return "Orc commander";
+    }
 }
diff --git a/chain/src/main/java/com/iluwatar/OrcKing.java b/chain/src/main/java/com/iluwatar/OrcKing.java
index 0d3f38ba23cc..94f73cefaa61 100644
--- a/chain/src/main/java/com/iluwatar/OrcKing.java
+++ b/chain/src/main/java/com/iluwatar/OrcKing.java
@@ -1,24 +1,23 @@
 package com.iluwatar;
 
 /**
- * 
  * Makes requests that are handled by the chain.
- * 
  */
 public class OrcKing {
 
-	RequestHandler chain;
+    RequestHandler chain;
 
-	public OrcKing() {
-		buildChain();
-	}
+    public OrcKing() {
+        buildChain();
+    }
 
-	private void buildChain() {
-		chain = new OrcCommander(new OrcOfficer(new OrcSoldier(null)));
-	}
+    private void buildChain() {
+        //创建职责链结构，从左到右依次处理请求。最后一级的下一级别是空的。
+        chain = new OrcCommander(new OrcOfficer(new OrcSoldier(null)));
+    }
 
-	public void makeRequest(Request req) {
-		chain.handleRequest(req);
-	}
+    public void makeRequest(RequestType req) {
+        chain.handleRequest(req);
+    }
 
 }
diff --git a/chain/src/main/java/com/iluwatar/OrcOfficer.java b/chain/src/main/java/com/iluwatar/OrcOfficer.java
index 9a9030eca1b0..fd715fc17a3f 100644
--- a/chain/src/main/java/com/iluwatar/OrcOfficer.java
+++ b/chain/src/main/java/com/iluwatar/OrcOfficer.java
@@ -2,22 +2,22 @@
 
 public class OrcOfficer extends RequestHandler {
 
-	public OrcOfficer(RequestHandler handler) {
-		super(handler);
-	}
+    public OrcOfficer(RequestHandler handler) {
+        super(handler);
+    }
 
-	@Override
-	public void handleRequest(Request req) {
-		if (req.getRequestType().equals(RequestType.TORTURE_PRISONER)) {
-			printHandling(req);
-		} else {
-			super.handleRequest(req);
-		}
-	}
+    @Override
+    public void handleRequest(RequestType req) {
+        if (req == RequestType.TORTURE_PRISONER) {
+            printHandling(req);
+        } else {
+            super.handleRequest(req);
+        }
+    }
 
-	@Override
-	public String toString() {
-		return "Orc officer";
-	}
+    @Override
+    public String toString() {
+        return "Orc officer";
+    }
 
 }
diff --git a/chain/src/main/java/com/iluwatar/OrcSoldier.java b/chain/src/main/java/com/iluwatar/OrcSoldier.java
index 0e5a5a603477..f84fe1b5c3ce 100644
--- a/chain/src/main/java/com/iluwatar/OrcSoldier.java
+++ b/chain/src/main/java/com/iluwatar/OrcSoldier.java
@@ -2,21 +2,21 @@
 
 public class OrcSoldier extends RequestHandler {
 
-	public OrcSoldier(RequestHandler handler) {
-		super(handler);
-	}
+    public OrcSoldier(RequestHandler handler) {
+        super(handler);
+    }
 
-	@Override
-	public void handleRequest(Request req) {
-		if (req.getRequestType().equals(RequestType.COLLECT_TAX)) {
-			printHandling(req);
-		} else {
-			super.handleRequest(req);
-		}
-	}
+    @Override
+    public void handleRequest(RequestType req) {
+        if (req == RequestType.COLLECT_TAX) {
+            printHandling(req);
+        } else {
+            super.handleRequest(req);
+        }
+    }
 
-	@Override
-	public String toString() {
-		return "Orc soldier";
-	}
+    @Override
+    public String toString() {
+        return "Orc soldier";
+    }
 }
diff --git a/chain/src/main/java/com/iluwatar/Request.java b/chain/src/main/java/com/iluwatar/Request.java
index 00cd239723d1..c82949abe9ac 100644
--- a/chain/src/main/java/com/iluwatar/Request.java
+++ b/chain/src/main/java/com/iluwatar/Request.java
@@ -2,32 +2,22 @@
 
 public class Request {
 
-	private String requestDescription;
-	private RequestType requestType;
+    private RequestType requestType;
 
-	public Request(RequestType requestType, String requestDescription) {
-		this.setRequestType(requestType);
-		this.setRequestDescription(requestDescription);
-	}
+    public Request(RequestType requestType) {
+        this.setRequestType(requestType);
+    }
 
-	public String getRequestDescription() {
-		return requestDescription;
-	}
+    public RequestType getRequestType() {
+        return requestType;
+    }
 
-	public void setRequestDescription(String requestDescription) {
-		this.requestDescription = requestDescription;
-	}
+    public void setRequestType(RequestType requestType) {
+        this.requestType = requestType;
+    }
 
-	public RequestType getRequestType() {
-		return requestType;
-	}
-
-	public void setRequestType(RequestType requestType) {
-		this.requestType = requestType;
-	}
-
-	@Override
-	public String toString() {
-		return getRequestDescription();
-	}
+    @Override
+    public String toString() {
+        return requestType.toString();
+    }
 }
diff --git a/chain/src/main/java/com/iluwatar/RequestHandler.java b/chain/src/main/java/com/iluwatar/RequestHandler.java
index 19dc33fcec8f..ca5b9d9a96d8 100644
--- a/chain/src/main/java/com/iluwatar/RequestHandler.java
+++ b/chain/src/main/java/com/iluwatar/RequestHandler.java
@@ -2,22 +2,30 @@
 
 public abstract class RequestHandler {
 
-	private RequestHandler next;
+    /**
+     * 下一级的引用
+     */
+    private RequestHandler next;
 
-	public RequestHandler(RequestHandler next) {
-		this.next = next;
-	}
+    public RequestHandler(RequestHandler next) {
+        this.next = next;
+    }
 
-	public void handleRequest(Request req) {
-		if (next != null) {
-			next.handleRequest(req);
-		}
-	}
+    /**
+     * 处理请求的默认方法，默认本级不处理，由下一级处理。
+     *
+     * @param req
+     */
+    public void handleRequest(RequestType req) {
+        if (next != null) {
+            next.handleRequest(req);
+        }
+    }
 
-	protected void printHandling(Request req) {
-		System.out.println(this + " handling request \"" + req + "\"");
-	}
+    protected void printHandling(RequestType req) {
+        System.out.println(this + " handling request \"" + req.toString() + "\"");
+    }
 
-	@Override
-	public abstract String toString();
+    @Override
+    public abstract String toString();
 }
diff --git a/chain/src/main/java/com/iluwatar/RequestType.java b/chain/src/main/java/com/iluwatar/RequestType.java
index 02176a088857..bd3d39758004 100644
--- a/chain/src/main/java/com/iluwatar/RequestType.java
+++ b/chain/src/main/java/com/iluwatar/RequestType.java
@@ -2,6 +2,15 @@
 
 public enum RequestType {
 
-	DEFEND_CASTLE, TORTURE_PRISONER, COLLECT_TAX
+    DEFEND_CASTLE("defend castle"), TORTURE_PRISONER("torture prisoner"), COLLECT_TAX("collect tax");
+    String name;
 
+    RequestType(String name) {
+        this.name = name;
+    }
+
+    @Override
+    public String toString() {
+        return name;
+    }
 }
diff --git a/command/src/main/java/com/iluwatar/App.java b/command/src/main/java/com/iluwatar/App.java
index 382ce32ce643..ccd9c8c00c17 100644
--- a/command/src/main/java/com/iluwatar/App.java
+++ b/command/src/main/java/com/iluwatar/App.java
@@ -5,7 +5,8 @@
  * In Command pattern actions are objects that can be executed and undone. 
  * 
  * In this example the commands are the spells cast by the wizard on the goblin.
- * 
+ * 在命令模式中，行为是一类可以被执行和撤销的对象。变化的方向是行为，而执行人是不变的。
+ * 在应用中，如果变化的部分都是动词可以考虑使用命令设计模式。将变化的动作封装为对象动态调用是命令设计模式的精髓。
  */
 public class App {
 
diff --git a/null-object/src/main/java/com/iluwatar/App.java b/null-object/src/main/java/com/iluwatar/App.java
index 4bba5af29f22..f2b2e57d8be1 100644
--- a/null-object/src/main/java/com/iluwatar/App.java
+++ b/null-object/src/main/java/com/iluwatar/App.java
@@ -1,32 +1,39 @@
 package com.iluwatar;
 
 /**
- * 
  * Null Object pattern replaces null values with neutral objects.
  * Many times this simplifies algorithms since no extra null checks
  * are needed.
- * 
+ * <p>
  * In this example we build a binary tree where the nodes are either
  * normal or Null Objects. No null values are used in the tree making
  * the traversal easy.
  *
+ * 空设计模式主要是应对频繁的非空判断。
+ * 他的做法是将Null也视为一个对象，只不过这个对象的每个方法都是空的，方法的返回值也都是默认的。
+ * 这样在被调用的时候就不需要做非空判断，如果这个对象是空对象，则会执行空方法而不是报空指针。
+ * 一下的例子演示了在遍历一棵树的时候，由于需要不断的判断左右是否为空，因此将空也作为一个节点。
+ * 这样就避免了在遍历的时候判空。
  */
-public class App 
-{
-    public static void main( String[] args ) {
-    	
-    	Node root = new NodeImpl("1",
-    			new NodeImpl("11",
-    					new NodeImpl("111",
-    							new NullNode(),
-    							new NullNode()),
-    					new NullNode()), 
-    			new NodeImpl("12",
-    					new NullNode(),
-    					new NodeImpl("122",
-    							new NullNode(),
-    							new NullNode())));
+public class App {
+    public static void main(String[] args) {
+/**
+ *           1
+ *      11       12
+ * 111               122
+ */
+        Node root = new NodeImpl("1",
+                new NodeImpl("11",
+                        new NodeImpl("111",
+                                new NullNode(),
+                                new NullNode()),
+                        new NullNode()),
+                new NodeImpl("12",
+                        new NullNode(),
+                        new NodeImpl("122",
+                                new NullNode(),
+                                new NullNode())));
 
-    	root.walk();
+        root.walk();
     }
 }
diff --git a/null-object/src/main/java/com/iluwatar/Node.java b/null-object/src/main/java/com/iluwatar/Node.java
index 1bb94927f110..7e69d77dfddf 100644
--- a/null-object/src/main/java/com/iluwatar/Node.java
+++ b/null-object/src/main/java/com/iluwatar/Node.java
@@ -1,15 +1,17 @@
 package com.iluwatar;
 
 /**
- * 
  * Interface for binary tree node.
- *
  */
 public interface Node {
 
-	String getName();
-	int getTreeSize();
-	Node getLeft();
-	Node getRight();
-	void walk();
+    String getName();
+
+    int getTreeSize();
+
+    Node getLeft();
+
+    Node getRight();
+
+    void walk();
 }
diff --git a/null-object/src/main/java/com/iluwatar/NodeImpl.java b/null-object/src/main/java/com/iluwatar/NodeImpl.java
index dbd5a7eca988..5a4e359b4841 100644
--- a/null-object/src/main/java/com/iluwatar/NodeImpl.java
+++ b/null-object/src/main/java/com/iluwatar/NodeImpl.java
@@ -1,50 +1,48 @@
 package com.iluwatar;
 
 /**
- * 
  * Implementation for binary tree's normal nodes.
- *
  */
 public class NodeImpl implements Node {
 
-	private final String name;
-	private final Node left;
-	private final Node right;
-	
-	public NodeImpl(String name, Node left, Node right) {
-		this.name = name;
-		this.left = left;
-		this.right = right;
-	}
-	
-	@Override
-	public int getTreeSize() {
-		return 1 + left.getTreeSize() + right.getTreeSize();
-	}
-
-	@Override
-	public Node getLeft() {
-		return left;
-	}
-
-	@Override
-	public Node getRight() {
-		return right;
-	}
-
-	@Override
-	public String getName() {
-		return name;
-	}
-
-	@Override
-	public void walk() {
-		System.out.println(name);
-		if (left.getTreeSize() > 0) {
-			left.walk();
-		}
-		if (right.getTreeSize() > 0) {
-			right.walk();
-		}
-	}
+    private final String name;
+    private final Node left;
+    private final Node right;
+
+    public NodeImpl(String name, Node left, Node right) {
+        this.name = name;
+        this.left = left;
+        this.right = right;
+    }
+
+    @Override
+    public int getTreeSize() {
+        return 1 + left.getTreeSize() + right.getTreeSize();
+    }
+
+    @Override
+    public Node getLeft() {
+        return left;
+    }
+
+    @Override
+    public Node getRight() {
+        return right;
+    }
+
+    @Override
+    public String getName() {
+        return name;
+    }
+
+    @Override
+    public void walk() {
+        System.out.println(name);
+        if (left.getTreeSize() > 0) {
+            left.walk();
+        }
+        if (right.getTreeSize() > 0) {
+            right.walk();
+        }
+    }
 }