yaclty/Java-Interview-Guide
1
0
Fork 0
mirror of https://github.com/Snailclimb/JavaGuide synced 2025-06-20 22:17:09 +08:00
Code Issues Projects Releases Wiki Activity

Merge pull request #218 from JerrySeven/master

Browse Source 
Update ArrayList-扩容问题
This commit is contained in:
SnailClimb 2019-03-19 19:26:41 +08:00 committed by GitHub
commit 06701ae856
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
1 changed files with 1 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
Java/ArrayList-Grow.md
View File

@ -145,7 +145,7 @@
}
```
**int newCapacity = oldCapacity + (oldCapacity >> 1),所以 ArrayList 每次扩容之后容量都会变为原来的 1.5 倍！** 记清楚了！不是网上很多人说的 1.5 倍+1！
**int newCapacity = oldCapacity + (oldCapacity >> 1),所以 ArrayList 每次扩容之后容量都会变为原来的 1.5 倍！（JDK1.6版本以后）** JDk1.6版本时，扩容之后容量为 1.5 倍+1！详情请参考源码
> ">>"（移位运算符）：>>1 右移一位相当于除2，右移n位相当于除以 2 的 n 次方。这里 oldCapacity 明显右移了1位所以相当于oldCapacity /2。对于大数据的2进制运算,位移运算符比那些普通运算符的运算要快很多,因为程序仅仅移动一下而已,不去计算,这样提高了效率,节省了资源