更新readme

crossoverJie · crossoverJie · commit de66e5d9daaa · 2017-12-25T15:17:25.000+08:00
diff --git a/MD/ArrayList.md b/MD/ArrayList.md
@@ -70,4 +70,23 @@
     }
 ```
 
+以及指定位置插入数据:
+```java
+    public void add(int index, E element) {
+        insertElementAt(element, index);
+    }
+        public synchronized void insertElementAt(E obj, int index) {
+        modCount++;
+        if (index > elementCount) {
+            throw new ArrayIndexOutOfBoundsException(index
+                                                     + " > " + elementCount);
+        }
+        ensureCapacityHelper(elementCount + 1);
+        System.arraycopy(elementData, index, elementData, index + 1, elementCount - index);
+        elementData[index] = obj;
+        elementCount++;
+    }
+```
+
+
 
diff --git a/README.md b/README.md
@@ -1,7 +1,7 @@
 # Java 面试常见题型
 
 ### Java 基础
-[ArrayList 底层分析](https://github.com/crossoverJie/Java-Interview/blob/master/MD/ArrayList.md)
+[ArrayList/Vector 底层分析](https://github.com/crossoverJie/Java-Interview/blob/master/MD/ArrayList.md)
 
 ### Java 多线程
 - [多线程中的常见问题](https://github.com/crossoverJie/Java-Interview/blob/master/MD/Thread-common-problem.md)
