diff --git a/src/java/io/InputStream.java b/src/java/io/InputStream.java
index d6702c6..4a1f97a 100644
--- a/src/java/io/InputStream.java
+++ b/src/java/io/InputStream.java
@@ -162,7 +162,8 @@ public int read(byte b[]) throws IOException {
      * <code>b.length - off</code>
      * @see        java.io.InputStream#read()
      *
-     * 将流中的数据读入，放在byte数组的地off位置的len位置
+     * 将流中的数据读入，放在byte数组的第off位置的len位置
+     * 该read(b, off, len)方法只是简单地反复调用方法read()
      */
     public int read(byte b[], int off, int len) throws IOException {
         if (b == null) {
@@ -170,6 +171,7 @@ public int read(byte b[], int off, int len) throws IOException {
         } else if (off < 0 || len < 0 || len > b.length - off) {
             throw new IndexOutOfBoundsException();
         } else if (len == 0) {
+            // 如果len为零，则不会读取字节并返回0 ;
             return 0;
         }
 
diff --git a/src/java/util/ArrayList.java b/src/java/util/ArrayList.java
index 5616402..ca90806 100644
--- a/src/java/util/ArrayList.java
+++ b/src/java/util/ArrayList.java
@@ -25,10 +25,11 @@
 
 package java.util;
 
+import sun.misc.SharedSecrets;
+
 import java.util.function.Consumer;
 import java.util.function.Predicate;
 import java.util.function.UnaryOperator;
-import sun.misc.SharedSecrets;
 
 /**
  * Resizable-array implementation of the <tt>List</tt> interface.  Implements
@@ -110,12 +111,13 @@ public class ArrayList<E> extends AbstractList<E>
     private static final long serialVersionUID = 8683452581122892189L;
 
     /**
-     * Default initial capacity.
+     * Default initial capacity.    默认容量
      */
     private static final int DEFAULT_CAPACITY = 10;
 
     /**
      * Shared empty array instance used for empty instances.
+     * size=0的空实例对象
      */
     private static final Object[] EMPTY_ELEMENTDATA = {};
 
@@ -131,19 +133,20 @@ public class ArrayList<E> extends AbstractList<E>
      * The capacity of the ArrayList is the length of this array buffer. Any
      * empty ArrayList with elementData == DEFAULTCAPACITY_EMPTY_ELEMENTDATA
      * will be expanded to DEFAULT_CAPACITY when the first element is added.
+     * 保存ArrayList中数据的数组
      */
     transient Object[] elementData; // non-private to simplify nested class access
 
     /**
      * The size of the ArrayList (the number of elements it contains).
-     *
+     * ArrayList的实际数据的数量
      * @serial
      */
     private int size;
 
     /**
      * Constructs an empty list with the specified initial capacity.
-     *
+     * 带容量参数的构造
      * @param  initialCapacity  the initial capacity of the list
      * @throws IllegalArgumentException if the specified initial capacity
      *         is negative
@@ -152,6 +155,7 @@ public ArrayList(int initialCapacity) {
         if (initialCapacity > 0) {
             this.elementData = new Object[initialCapacity];
         } else if (initialCapacity == 0) {
+            // 1.6版本的是直接初始化一个容量为10的对象，现在是初始化为容量=0的对象
             this.elementData = EMPTY_ELEMENTDATA;
         } else {
             throw new IllegalArgumentException("Illegal Capacity: "+
@@ -161,6 +165,7 @@ public ArrayList(int initialCapacity) {
 
     /**
      * Constructs an empty list with an initial capacity of ten.
+     * 空参构造，默认容量=0，1.6版本的默认容量为10
      */
     public ArrayList() {
         this.elementData = DEFAULTCAPACITY_EMPTY_ELEMENTDATA;
@@ -170,7 +175,7 @@ public ArrayList() {
      * Constructs a list containing the elements of the specified
      * collection, in the order they are returned by the collection's
      * iterator.
-     *
+     * 创建一个包含collection的ArrayList
      * @param c the collection whose elements are to be placed into this list
      * @throws NullPointerException if the specified collection is null
      */
@@ -181,7 +186,7 @@ public ArrayList(Collection<? extends E> c) {
             if (elementData.getClass() != Object[].class)
                 elementData = Arrays.copyOf(elementData, size, Object[].class);
         } else {
-            // replace with empty array.
+            // replace with empty array. 依然将数据为0的情况独立出来，替换为容量=0的对象
             this.elementData = EMPTY_ELEMENTDATA;
         }
     }
@@ -190,6 +195,7 @@ public ArrayList(Collection<? extends E> c) {
      * Trims the capacity of this <tt>ArrayList</tt> instance to be the
      * list's current size.  An application can use this operation to minimize
      * the storage of an <tt>ArrayList</tt> instance.
+     * 将当前容量值设为 =实际元素个数
      */
     public void trimToSize() {
         modCount++;
@@ -204,6 +210,7 @@ public void trimToSize() {
      * Increases the capacity of this <tt>ArrayList</tt> instance, if
      * necessary, to ensure that it can hold at least the number of elements
      * specified by the minimum capacity argument.
+     * 确定ArrayList的容量
      *
      * @param   minCapacity   the desired minimum capacity
      */