diff --git a/src/chapter6/demo64/Card.java b/src/chapter6/demo64/Card.java
index ef92fa8..2cd1d4c 100644
--- a/src/chapter6/demo64/Card.java
+++ b/src/chapter6/demo64/Card.java
@@ -2,9 +2,9 @@ package chapter6.demo64;
 
 // Card.java - 扑克牌类
 public class Card implements Comparable<Card> {
-    private String color;       // 花色
-    private String point;       // 点数
-    private int index;          // 编号
+    private final String color;       // 花色
+    private final String point;       // 点数
+    private final int index;          // 编号
 
     /**
      * 构造一张扑克牌
@@ -25,6 +25,14 @@ public class Card implements Comparable<Card> {
 
     @Override
     public int compareTo(Card other) {
+//        if (this.index == other.index) {
+//            return 0;
+//        } else if (this.index > other.index) {
+//            return 1;
+//        }  else {
+//            return -1;
+//        }
+        // 谁的index小，谁排在前面
         return this.index - other.index;
     }
 
diff --git a/src/chapter6/demo64/Deck.java b/src/chapter6/demo64/Deck.java
index de19d28..6b79edb 100644
--- a/src/chapter6/demo64/Deck.java
+++ b/src/chapter6/demo64/Deck.java
@@ -38,7 +38,7 @@ public class Deck {
      */
     public Card dealCard() {
         if (!cards.isEmpty()) {
-            return cards.remove(0);
+            return cards.removeFirst();
         }
         return null;
     }
diff --git a/src/chapter6/demo64/Player.java b/src/chapter6/demo64/Player.java
index cb05b5a..595cdab 100644
--- a/src/chapter6/demo64/Player.java
+++ b/src/chapter6/demo64/Player.java
@@ -9,6 +9,10 @@ public class Player {
     private String name;
     private ArrayList<Card> hand = new ArrayList<>();
 
+    /**
+     * 构造函数
+     * @param name 玩家名称
+     */
     public Player(String name) {
         this.name = name;
     }