From 7d1e2970a651fff93470d8110172102c1a489318 Mon Sep 17 00:00:00 2001
From: ranwenjie <ranwenjie@didichuxing.com>
Date: Mon, 26 Apr 2021 21:44:25 +0800
Subject: [PATCH] update hashmap

---
 3 Hash Table/HashMap in Java.md | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/3 Hash Table/HashMap in Java.md b/3 Hash Table/HashMap in Java.md
index 3c918d7..1285ac4 100644
--- a/3 Hash Table/HashMap in Java.md	
+++ b/3 Hash Table/HashMap in Java.md	
@@ -311,7 +311,9 @@ https://bugs.java.com/bugdatabase/view_bug.do?bug_id=4631373 提出， 整数的
 举个例子
 ```
 hashcode 311 对应的二进制是(1 0011 0111)
-length 16  对应的二进制是(1 0000)
+length 16  对应的二进制是(1 0000) ,  length-1 就是 （0 1111）
+
+h & (length-1)` 就是取 hashcode 的低 4位
 
 ```